A friend told me recently that coffee stopped working for her. Not in a “I need a second cup” way; in a “I need a bucket” way. Which, if you read my coffee post, you know is not exactly the goal. (We’re aiming for a 2-3 cup sweet spot)

She was troubleshooting life the way most of us do. Maybe it’s the coffee. Maybe it’s her tolerance. Maybe she needs a stronger blend.

But I kept thinking...the problem probably isn’t the coffee. Her body might be so under-recovered that no amount of stimulation is going to fix it.

Around the same time, I noticed something in my own life: on nights after a heavy leg workout, my sleep was consistently terrible…two patterns, two different people, same underlying issue. And so down the rabbit hole I went.

Turns out, for many of us, it’s not an energy problem...it’s a recovery problem.

The Signs You’re Ignoring (or Attributing to Something Else)

Under-recovery appears in different ways:

• Elevated resting heart rate or reduced heart rate variability (HRV)

• Impaired sleep quality, particularly reduced deep sleep

• Increased perceived effort during workouts at the same intensity (or just during everyday tasks; the stairs feel harder, the grocery bags feel heavier)

• Blunted performance or progress despite consistent effort

• Increased reliance on stimulants (caffeine, pre-workouts, energy drinks...whatever your version is)

• Feeling “wired but tired”; mentally stimulated but physically flat

• Getting sick more often or taking longer to bounce back from minor illness

• Brain fog, shorter fuse, trouble concentrating

If you train, you might notice this as stalled lifts or workouts that feel disproportionately hard. If you don’t train, you might notice it as the kind of fatigue that sleep doesn’t seem to fix, or a general sense that your body just isn’t keeping up with your life. Maybe it’s the sudden need for a bucket of coffee.

From a physiological standpoint, both versions reflect the same thing: autonomic imbalance. Your sympathetic nervous system remains elevated while parasympathetic recovery can’t catch up. A 2024 study confirmed that exhaustive exercise significantly suppresses parasympathetic activity while simultaneously elevating sympathetic markers. But chronic psychological stress does the same thing; research on allostatic load shows that sustained work stress, caregiving stress, and emotional strain produce the same autonomic profile. HRV monitoring is one of the best early-warning systems we have, whether the load is physical or not.

In plain English: maybe it’s not exactly burnout, but backlog?

Your Body Doesn’t Compartmentalize a Stressor

Exercise is a stressor...a beneficial one, but still a stressor. During and after training, cortisol rises to mobilize energy, adrenaline increases to support output, and inflammatory signals initiate tissue repair. This is expected and necessary.

But your body mounts a similar hormonal response to psychological stress. A demanding job, a rough week with the kids, financial pressure, a relationship that’s draining you...cortisol rises for all of it. The biology doesn’t distinguish between physical and emotional load. It just responds.

These signals are meant to be transient. When recovery is insufficient; from training, from life, or from both; the effects accumulate. Researchers call this allostatic load; the total “wear and tear” on the body from chronically activated stress responses. You can read this post about stress for more on the bigger concept.

Intense workouts plus cognitive stress (work, screens, constant input) plus insufficient sleep plus inconsistent nutrition...your body doesn’t separate any of this. And you don’t need to be training at all for this to apply. A stressful job on top of poor sleep on top of skipped meals is its own version of cumulative load. And then we try to fix it by adding more inputs; another supplement, another stimulant, another layer of optimization.

In plain English: You can’t stimulate your way out of a system that hasn’t restored baseline. At some point, the answer isn’t more...it’s less.

What’s Happening Inside, Biologically

Fun fact: your body doesn’t get stronger during a workout. It gets stronger after, through a tightly coordinated biological process that most of us are interrupting without realizing it.

Here is what should happen: after training, your body initiates muscle protein synthesis (MPS) to repair and rebuild damaged muscle fibers. MPS increases by 50% at 4 hours post-exercise and peaks at 109% above baseline at 24 hours. By 36 hours, it’s heading toward or back to normal. That’s your recovery window. Not 30 minutes, not the “anabolic window” the supplement industry loves to talk about; the real window is closer to 24 to 48 hours, depending on the body part (see chart below). And a shout out to for reminding me of this window!

At the very same time it’s doing its MPS thing, your body is also replenishing glycogen stores in muscle and liver, your nervous system is shifting from sympathetic (”go”) to parasympathetic (”recover”) dominance, and hormonal signaling (growth hormone, testosterone, insulin sensitivity) ramps up to support the whole process. It’s…a lot, but when it’s working smoothly, you get your gains, your energy, your improvements.

Exercise physiologists call this the supercompensation model: stress, then recovery, then a rebound to a level above your previous baseline. Without a full recovery phase, you interrupt that cycle. You don’t get stronger; you just accumulate fatigue. And remember, our bodies run this same recovery machinery whether the stress came from a barbell or a boardroom.

The recovery window varies by muscle group. Larger muscles need more time; smaller ones bounce back faster. Here’s a general breakdown:

So what does recovery actually require? Three things. Just three. But most of us are falling short on at least one of them.

The Three Pillars of Recovery

1. Eat Enough

Recovery is quite metabolically expensive, and your body simply cannot recover without adequate fuel. Period. (sorry, all my GLP-ers, you must push through it.)

Protein supports muscle protein synthesis and tissue repair; read this protein post to go deeper on why, but even if you’re not training, adequate protein matters for maintaining muscle mass, immune function, and hormone production.

And then there are carbohydrates. They’re not just fuel, but recovery signals. (Yes, I said that.) A 2022 systematic review found that low-carbohydrate diets significantly elevated post-exercise cortisol, and the elevation persisted even after adaptation to the diet. A meta-analysis in Medicine and Science in Sports and Exercise found that coingesting protein with carbohydrate after exercise enhanced glycogen repletion and overall recovery beyond what carbohydrate alone could do. That’s why I usually pound this protein shake that includes carbs the moment I get in the car after a workout.

And so it’s said out loud: skipping meals, chronic under-eating, or relying on caffeine instead of actual food keeps your body in a stress state. If you’re running on stress and running on empty, your body can’t recover from either.

In plain English: When you eat enough; especially protein and carbs; your cortisol comes down faster and your body gets the “all clear” to start rebuilding. Skip them, and your stress hormones stay elevated longer.

2. Sleep Enough

I know, I know...easy to proclaim GET MORE SLEEP…much harder to make it happen. But we must try our best, because this is where recovery shines.

Sleep is an active biological construction site. UC Berkeley researchers put it like this: “Sleep drives growth hormone release, and growth hormone feeds back to regulate wakefulness. This balance is essential for growth, repair, and metabolic health.” This is why those who take growth hormone peptides take them at night, to bolster this effect.

And then there’s the brain’s cleanup crew, which I will do a dedicated post about one Monday because it is incredibly interesting. The glymphatic system is a waste clearance network that uses cerebrospinal fluid to flush metabolic byproducts from your brain. It’s 80 to 90% more active during slow-wave (deep) sleep than during wakefulness. The system literally can’t do its job unless you’re asleep.

The data on sleep loss is stark. A 2021 study found that a single night of sleep deprivation reduced muscle protein synthesis by 18% and shifted the hormonal environment toward catabolism (higher cortisol, lower testosterone). One night. A 2024 meta-analysis confirmed that sleep deprivation significantly impairs performance across the board and increases perceived exertion, with the effect felt the worst in the afternoon.

Remember my leg day sleep problem? Here’s what I found. Our largest muscle groups are in our legs: quads, glutes, hamstrings. Training them hard creates significantly more metabolic heat, more muscle tissue damage, and a bigger inflammatory response than an upper body session. Core body temperature rises 0.5 to 1.5 degrees Celsius during heavy resistance training, and the larger the muscle mass involved, the longer it takes to dissipate. That matters because sleep onset is tightly coupled to a decline in core body temperature; your brain essentially needs the body to cool down before it can initiate deep sleep. On top of that, exhaustive exercise drives your autonomic nervous system into prolonged sympathetic dominance, with parasympathetic recovery (the “calm down” signal) suppressed by as much as 94%. A 2020 study found that resistance training to failure (hi, my favorite) produced measurable fatigue that persisted into the next day, with half-squat strength dropping 11% at 24 hours. The body was still recovering well past bedtime.

In plain English: A big (leg or otherwise) day creates a perfect storm for bad sleep: elevated core temperature that won’t come down, a nervous system stuck in “go” mode, and a massive repair job that your body is trying to start before you’ve even turned the lights off.

The fix isn’t to stop training legs, obviously; it’s to plan around it...eating enough carbohydrates post-workout to bring cortisol down and start glycogen repletion, maybe taking a warm bath or doing a sauna session later in the day to force your body into cooling mode, and keeping your sleep environment cool. For the record, I started adding rice to my lunch, and my sleep improved.

So, all that to say that seven to nine hours isn’t a luxury. It’s part of the protocol for athletes and for everyone else. (And for some people, six hours works. Genetics play a role here. But if you’re running on six and wondering why you feel terrible...maybe test that theory.)

In plain English: Sleep is where recovery actually happens. Growth hormone peaks, tissue repair accelerates, and your brain takes out the trash. Shortchange it and you’ll fall behind on every recovery process running.

3. Give It Time

This is the one that took me a while to wrap my head around, because it goes against everything we’ve been told about discipline and consistency. So I will say it plainly, and hopefully you will catch on quicker than I did:

Your body needs time between stressors to complete the recovery cycle. If you keep loading stress on top of incomplete recovery, you’re not building; you’re just digging a deeper hole.

If you train, not every day should be high intensity or the same body part. Periodized training programs produce significantly greater strength gains than non-periodized approaches, largely because they build recovery into the structure.

Here is a helpful body part chart for you:

On your “off” days, you can do Zone 2 training (steady, conversational-pace cardio at roughly 60 to 70% of max heart rate), walking, and mobility work. The easy days are what make the hard days productive.

If you don’t train: the same principle applies to your life. You can’t run at full capacity every single day and expect your body to keep up. If every day is back-to-back meetings, late nights, early mornings, and high cognitive demand...that’s the equivalent of training to failure seven days a week. Build in lower-output days. Take a walk. Eat a real lunch instead of inhaling something at your desk. The concept is the same; your system needs contrast between stress and recovery to function well.

Recovery also requires a shift into parasympathetic dominance. Post-meal walks, breathwork, reducing late-night stimulation, and consistent sleep/wake timing all support this.

Code Red: When All Three Fail at Once

Here’s what it looks like when these three pillars collapse on each other.

A study of athletes undergoing intense training found that cortisol levels were significantly higher in those with poor sleep quality compared to those sleeping well. And that elevated cortisol independently predicted poor sleep. It’s a feedback loop; stress raises cortisol, high cortisol disrupts sleep, poor sleep impairs recovery, impaired recovery keeps cortisol high. This loop runs the same way whether the original stressor was a workout or a 60-hour work week.

The catabolic (fancy word for breaking down) effects are measurable. A study in the American Journal of Physiology demonstrated that stress-level cortisol increases muscle protein breakdown by 65%, with protein synthesis only partially compensating (a 48% increase). The net result is muscle loss, not muscle gain. All that work for nothing.

And then there’s the immune connection. Exercise immunology research describes an “open window” of suppressed immune function lasting 3 to 72 hours after heavy exertion, driven largely by elevated cortisol and depleted glutamine. If you’ve ever had a hard training week and then caught a cold...that’s the window. Chronic life stress produces a similar effect; prolonged cortisol elevation suppresses immune surveillance regardless of the source. (Newer research from a 2018 review argues the “open window” may reflect immune redistribution rather than true suppression, but either way, the message is the same: recovery matters for staying healthy.)

High-intensity training also taxes the central nervous system (CNS), not just muscles. A 2019 study found that physical training overload induces cognitive fatigue in the same brain regions used for decision-making and self-control. Overtrained athletes made more impulsive choices in economic tasks. And this isn’t exclusive to athletes; chronic work stress, decision fatigue, and sleep debt tax the same prefrontal regions. If you’ve ever made terrible food choices at the end of a long day, or found yourself unable to think clearly by 3pm...that’s the same neural depletion.

In plain English: Being under-recovered doesn’t just make your body tired. It makes your brain tired. And a tired brain makes worse decisions about food, sleep, priorities, and self-care...which makes the whole cycle worse.

This is why everything starts to feel harder. You’re not weaker…you’re under-recovered.

A Note on Supplements

Creatine supports ATP regeneration and recovery (yes, I take 10g daily (code YBM to save 10%); read All About Creatine for the full breakdown).

Electrolytes support hydration and neuromuscular function.

Magnesium may support sleep quality and relaxation, tart cherry helps boost melatonin. (If you like an all-in-one kind of formula, I recently started taking SureSleep and am loving it. Code: YBM for 10% off)

But these sit on top of, not in place of, the three pillars above. Supplements are the (tart) cherry, ha! Recovery is the sundae.

In Case You Skimmed

• Your body doesn’t compartmentalize stress; training, work, sleep debt, and under-eating all feed the same allostatic load equation

• Muscle protein synthesis peaks at 109% above baseline at 24 hours post-exercise; the real recovery window is 24 to 48 hours, not 30 minutes

• Recovery requires three things: eating enough, sleeping enough, and time between stressors

• Chronic cortisol elevation increases muscle protein breakdown by 65% and disrupts sleep, creating a feedback loop that applies to physical and psychological stress alike

• One night of sleep deprivation reduces muscle protein synthesis by 18%; the glymphatic system is 80 to 90% less active when you’re awake

• Low-carb diets significantly elevate cortisol; carbohydrates are recovery signals, not the enemy

This week, instead of asking “how can I do more?”...ask what it would look like to actually rest and recover from what you’ve already done. If you train, maybe that’s more spread out high-intensity sessions. If you don’t, maybe it’s one evening where you actually stop working. For everyone: one better night of sleep, one properly fueled day is not doing less; it’s giving your body the space to finally catch up. Then, let’s see how you feel by next Monday.

See you then,
Susan

Longevity In The Wild

A friend, looking rather frazzled, ran up to me at a coffee shop the other day and blurted, “I’ve been meaning to call you...my central nervous system is going crazy because I’m so stressed, and I need you to tell me how to calm down.” And without even waiting for a reply, she was off and running to her day.

I think we’ve all been in exactly this position. Can’t catch up, can’t find room, overwhelmed by it all. I usually make this section unrelated to the post above, but this one felt too fitting not to include.

I’m no psychologist, but I do find there’s something helpful in saying the thing out loud; moving it from an internal thought loop to an external monkey on someone else’s back. And sometimes that old phrase “if you’re going through hell, keep going” is the best response...just to impart some hope that it will eventually turn out ok.

I also realize the irony of writing a post about all the things your body needs to recover, then watching someone’s eyes glaze over because it feels like yet another list of things to get right. That’s not the goal. If the three pillars above feel like a lot, start with the smallest one: a breath. Box breathing (four counts in, four counts hold, four counts out, four counts hold) is free, takes 60 seconds, and it’s one of the fastest ways to nudge your nervous system toward the parasympathetic side. That, plus having a friend you can say the thing out loud to, can be enough to hang on until you’re on the other side.

Coffee is the one “supplement” nobody calls a supplement. Two billion cups a day, and I bet you don’t know what’s in it. Not the caffeine...everybody knows about the caffeine. I mean the other 2,000 bioactive compounds that make coffee one of the most studied substances in nutritional science.

Coffee contains more polyphenols (antioxidants and anti-inflammatory compounds) per serving than blueberries or green tea. It’s the single richest source of chlorogenic acid (anti-inflammatory, neuroprotective, anti-diabetic) in the Western diet. And the research on what it does to the human body has done a complete about face. In the 1980s, the American Cancer Society told people to avoid it. Now, the data says it might be one of the most protective things you consume all day.

I’m pro-coffee. Strongly. And I think when you see the data, you will be too...or at least you’ll feel more enthusiastic about that second cup.

, , and, well, everyone else, refill that mug and buckle up.

A Brief History of Coffee

Coffee’s origin story is almost too good. The legend goes that a 9th-century Ethiopian goat herder named Kaldi noticed his goats dancing after eating berries from a certain tree. He tried them. He danced too. A monk saw the whole thing, brewed the berries into a drink, and discovered he could stay awake through evening prayers. Whether or not Kaldi’s goats were real, coffee cultivation took root in Yemen by the 15th century, Ottoman coffeehouses became the intellectual hubs of the 1600s, and by the 18th century, coffee had conquered Europe.

The health narrative has been a rollercoaster. In 1991, the WHO classified coffee as a possible carcinogen. By 2016, they reversed that entirely, citing growing evidence of benefit. And here we are.

Coffee For Longevity

A 2024 comprehensive review analyzed over 50 international cohort studies and found that regular coffee consumption is associated with approximately 1.8 years of added healthy life expectancy. Not just lifespan…healthspan. Optimal intake was around 3 cups per day.

The UK Biobank study in JAMA Internal Medicine followed roughly 500,000 people and found an inverse association between coffee and all-cause mortality that held even at 8+ cups per day, for ground, instant, and decaf. Whether you’re a fast or slow caffeine metabolizer (we’ll get to that), the mortality data looks the same.

A 2025 study in the European Heart Journal tracked about 40,000 US adults and found that morning coffee drinkers had 31% lower cardiovascular mortality. All-day drinkers showed no significant benefit, leading one to think that timing might matter as much as quantity.

A 2025 Nutrients review confirmed what the individual studies kept showing: 3 to 5 cups per day is consistently associated with lower mortality and reduced risk of cardiovascular disease, type 2 diabetes, certain cancers, cognitive decline, and respiratory illness. The lowest mortality risk landed at about 3.5 cups daily.

This is all sounding great…and it only gets better!

The Polyphenol Engine

The reason decaf shows up in the mortality data is the same reason coffee is more than just caffeine: chlorogenic acid (CGA). A single cup contains roughly 200 to 550 mg of it, which is more than most polyphenol supplements on the market. CGA scavenges free radicals, reduces inflammatory markers like TNF-alpha and COX-2, inhibits glucose absorption in the gut, and promotes nitric oxide release from blood vessel walls.

In plain English: The most powerful compound in coffee isn’t caffeine. It’s a polyphenol most people have never heard of, and you’re getting a therapeutic dose every morning without trying. Congrats!

But not so fast…

The Freshness Clock

There’s a catch…polyphenols are not patient. The second you grind coffee, the surface area explodes and oxidation starts immediately; up to 80% of the CO2 that protects those compounds escapes within 60 seconds. Caffeic acid (one of the key antioxidant polyphenols) is especially vulnerable to oxidation once the bean structure is broken open. By 15 minutes, you’ve lost a noticeable amount of aromatic and phenolic compounds. By 30 minutes, the difference is substantial.

Once brewed, the clock keeps ticking. Chlorogenic acids break down into quinic and caffeic acids over time (that’s the bitterness you taste in old coffee). Peak polyphenol profile is in that first 15 to 30 minutes after brewing.

The practical version: Grind, then brew within 5 minutes. Drink within 30 minutes. If you can’t drink it right away, a thermal carafe slows the degradation...but nothing stops it. Pre-ground coffee sitting in your pantry for weeks has already lost a meaningful chunk of what makes coffee protective in the first place. Sad, I know. But now you know, so you can grind and brew and drink accordingly.

Autophagy: Your Cells’ Cleanup Crew

This one surprised me. In 2014, researchers at the Institut Gustave Roussy gave mice either regular or decaffeinated coffee and found that both triggered autophagy in the liver, muscle, and heart within 1 to 4 hours. The mechanism was mTORC1 inhibition plus protein deacetylation...which, if that means nothing to you, is the same pathway activated by caloric restriction and fasting.

This is particularly interesting for anyone who practices intermittent fasting. Black coffee (roughly 3 to 5 calories) does not break a fast, does not trigger a meaningful insulin response, and may actually deepen the fasted state by enhancing fat oxidation. Adding cream, sugar, or butter disrupts this. Black is the only way.

In plain English: Coffee tells your cells to start cleaning house, and caffeine isn’t even required to flip that switch.

Cellular Aging: The AMPK Connection

This is the newest piece of the puzzle. A 2025 study in Microbial Cell found that caffeine activates AMPK (AMP-activated protein kinase), a cellular fuel gauge that senses when your cells are low on energy. When AMPK flips on, it triggers a cascade: improved DNA repair, better stress response, and more controlled cell growth. These are the same pathways that caloric restriction and exercise activate. Coffee is essentially mimicking a fasted, active state at the cellular level.

And a November 2025 study in BMJ Mental Health took this further. Researchers found that people who drank 3 to 4 cups of coffee per day had longer telomeres (the protective caps on your chromosomes that shorten as you age, like those caps at the end of shoelaces). Their telomere length was comparable to people about 5 years younger biologically. The likely mechanism: coffee’s antioxidants reduce the oxidative stress that drives telomere shortening.

In plain English: Coffee doesn’t just slow disease. At the cellular level, it appears to slow aging itself.

The Liver Data

Coffee’s most consistent protective effects show up in the liver: 29% lower risk of non-alcoholic fatty liver disease (MASLD), 39% lower risk of cirrhosis across all causes, and a 40 to 41% reduction in liver cancer risk. The liver cancer data is dose-dependent; at 4+ cups per day, risk reduction hits 41%.

In plain English: If your liver could talk, it would ask you to keep drinking coffee.

Type 2 Diabetes

A meta-analysis of 30 prospective studies covering over 1.1 million participants found each additional cup of coffee reduced type 2 diabetes risk by about 6%. At 5 cups per day, that’s a 29% reduction. Both caffeinated and decaf showed the effect, pointing to chlorogenic acid as the driver.

Critical caveat: a 2025 update found that this protective effect is eliminated when sweeteners and creamers are added. The coffee protects you; the stuff you put in it can undo that protection.

The Brain

A February 2026 study published in JAMA just dropped some of the strongest brain data yet. Researchers from Harvard, Mass General Brigham, and the Broad Institute followed 131,821 people for up to 43 years and found that those with the highest caffeinated coffee intake had an 18% lower risk of dementia. Caffeinated coffee drinkers also showed lower rates of subjective cognitive decline (7.8% vs. 9.5%) and performed better on objective cognitive tests. The sweet spot was 2 to 3 cups per day. Decaf showed no benefit here, which suggests caffeine itself is doing the neuroprotective work.

The Parkinson’s data tells a similar story with an interesting twist. A 2019 finding from the Parkinson’s Foundation showed that caffeine alone had minimal protective benefit in animal models, and EHT (a fatty acid naturally present in coffee) alone was also minimal. But the combination of both was significantly protective, reducing alpha-synuclein clumping and preserving neuron integrity.

In plain English: Coffee appears to protect the brain through multiple mechanisms. For dementia, it’s likely the caffeine. For Parkinson’s, it’s the combination of compounds working together.

The Heart

This one surprised a lot of cardiologists. For years, the conventional wisdom was that coffee triggers arrhythmias. The DECAF trial, published in JAMA in late 2025, flipped that on its head. It was the first long-term randomized controlled trial of caffeinated coffee on a cardiovascular endpoint. Two hundred adults with atrial fibrillation were randomized to either drink coffee daily or abstain completely for six months. The coffee drinkers had a 40% lower risk of AFib recurrence. Surprise!

A separate 2025 observational study found that 1 to 3 cups of black coffee per day was associated with a 14% lower overall mortality risk and a significant reduction in cardiovascular death. The key word there is black; adding sugar and saturated fats erased the benefit.

In plain English: Coffee doesn’t stress your heart. The latest data says it protects it...as long as you’re not drowning it in cream and sugar.

Timing: The Cortisol Debate

Stop me if you’ve heard this one: wait 90 minutes after waking before your first cup. The logic behind this is that our body produces a natural cortisol spike (the awakening response) that peaks about 30 to 60 minutes after waking. Stacking caffeine on top of that spike could amplify stress hormones unnecessarily. Better to let cortisol do its job, then use caffeine when it naturally dips.

The stronger version of the argument is actually about adenosine, not cortisol. Adenosine is the molecule that builds up in your brain the longer you’re awake…it’s what makes you feel sleepier and sleepier as the day goes by. Adenosine levels are at their lowest right after you wake up (because you just cleared them during sleep). Caffeine works by blocking adenosine receptors, so if there’s barely any adenosine to block, caffeine doesn’t have much to work with. Waiting a bit lets a bit of adenosine accumulate.

It’s a clean theory. The problem is that no one has confirmed it. What does have strong evidence is the morning-only vs. all-day pattern. The 2025 European Heart Journal study showing 31% lower cardiovascular mortality for morning drinkers. The data supports front-loading your coffee, even if the 90-minute rule is more theoretical than proven.

Which leads us into the crux of the timing issue…

Caffeine Metabolism

Not all caffeine hits people the same way. The reason one person can have an espresso after dinner and sleep like a baby while another is wired until 2 AM comes down to one gene: CYP1A2.

Fast vs. Slow Metabolizers

Your liver produces an enzyme called CYP1A2 that’s responsible for breaking down about 95% of the caffeine you consume. How much of that enzyme you produce is determined by your genetics. If you inherited two copies of the fast variant, you’re a fast metabolizer; caffeine clears your system quickly, the effects are shorter, and you can generally handle more of it without issues. If you have one or two copies of the slow variant, you’re a slow metabolizer; caffeine lingers in your system much longer, the effects are more intense, and you’re more susceptible to jitteriness, anxiety, and sleep disruption.

About 50 to 60% of the population carries the slow variant. So if caffeine has always hit you harder than it seems to hit everyone else, you’re actually in the majority.

Caffeine’s half-life (the time it takes for your body to clear half of it) is 5 to 6 hours on average. But for fast metabolizers, it can be as short as 2 hours. For slow metabolizers, it can stretch to 10.

How to Tell (Without a Genetic Test)

Not everyone has spit in a tube and sent it off to a lab, and that’s fine. Your body has been giving you the answer for years.

Signs you’re a fast metabolizer: You can drink coffee after dinner and still fall asleep on time. One cup barely moves the needle anymore. Your afternoon coffee wears off suspiciously fast. You tend to drink more coffee overall because the effects don’t stick around. (I’m a confirmed fast caffeine metabolizer, verified by genetic testing).

Signs you’re a slow metabolizer: One cup at 2 PM means you’re staring at the ceiling at midnight. You get jittery or anxious from a single cup. Your heart rate noticeably spikes after coffee. You feel wired long after everyone else has moved on.

The simplest self-test: skip caffeine for a few days, then drink one cup at noon and track how you feel at 4 PM, 8 PM, and bedtime. If it’s mostly cleared by dinner, you’re on the faster end. Still buzzing at 9 PM...now you know.

The Afternoon Cutoff

A 2025 randomized crossover trial in the journal Sleep found that 100 mg of caffeine (about one cup) caused no significant sleep disruption at any time point. But 400 mg taken 4 hours before bed reduced total sleep time by 50 minutes and cut slow-wave sleep by nearly 30 minutes. Even at 8 hours before bed, 400 mg still caused measurable fragmentation. And here’s the kicker: subjects couldn’t perceive the disruption; they thought they slept fine.

If you’re a slow metabolizer, you might want an earlier cutoff...and possibly pay more attention to the cortisol argument.

A Hack for Fast Metabolizers

If your morning cup wears off too quickly, add a small amount of fat. Dietary fat slows gastric emptying, so caffeine absorbs more gradually over a longer window. Smoother energy curve instead of a spike and crash. Olive oil works (Starbucks built an entire product line around it), and it brings its own polyphenols. Coconut oil, MCT oil, or simply drinking coffee with a meal all do the trick.

One caveat if you’re watching your LDL: fat in unfiltered coffee could help your body absorb more cafestol (that word will make sense in a moment).

What’s in Your Cup And What Shouldn’t Be

The Creamer Problem

Coffee Mate’s ingredient list starts with water, corn syrup solids, and vegetable oil. International Delight leads with water, palm oil, and sugar, plus carrageenan, an emulsifier associated with gut inflammation in some research.

That type 2 diabetes data showing a 29% risk reduction...it disappears entirely when sweeteners and creamers are added. For scale:

• Black brewed coffee: 5 calories

• Vanilla Latte: 250 calories

• Pumpkin Spice Latte: 390 calories

• Caramel Ribbon Crunch Frappuccino: 470 calories

Each pump of flavored syrup adds 20 to 25 calories, and a typical Grande gets 4 pumps.

In plain English: If you are adding flavored oil and sugar, your “coffee” at that point is a different beverage.

Mycotoxins: Real Concern or Marketing?

Mycotoxins can grow on coffee beans during storage and processing, and traces show up in 50 to 90% of green bean samples. But exposure amounts to only 2 to 3% of the safe limit set by international food safety authorities. Roasting reduces them further. The “mold-free coffee” category is mostly marketing.

If you have MCAS (we will cover this, as I’ve self-diagnosed this, ha!), are recovering from mold exposure, or are immunocompromised, a lab-tested brand makes sense. For everyone else, you’re fine. But if you want peace of mind: Holistic Roasters (Demeter-certified biodynamic, publishes batch lab results), Natural Force (USDA Organic, posts certificates of analysis publicly), and Purity Coffee (USDA Organic, Rainforest Alliance, 65% higher antioxidants than 46 other brands tested) are all doing it right.

Acrylamide: The Emerging Marketing Scare

Acrylamide forms when coffee is roasted. It’s classified as a “probable human carcinogen”...based on animal studies where doses were 1,000 to 100,000 times higher than typical human exposure. The overall cancer data on coffee shows risk reduction, not increase. Dark roasts have less acrylamide than medium roasts. If this concerns you: drink dark roast, skip instant, and move on with your morning.

The Cafestol Problem (For the LDL Watchers)

Here’s the callback from earlier. This section is personal because I watch my LDL, and this is the one legitimate health concern with coffee that I take seriously.

Cafestol is a diterpene in the oily fraction of coffee beans. It acts as an agonist for FXR receptors in the intestine, suppressing the enzyme that converts cholesterol into bile acids. It also downregulates LDL receptors by about 18%.

In plain English: Cafestol tells your body to stop recycling cholesterol. LDL goes up because it has nowhere to go.

But it is SO EASY to control this. How much ends up in your cup depends entirely on your brewing method:

Brewing Method | Cafestol Per Cup | LDL Impact

• French press | ~7.2 mg | Very high impact

• Espresso (single shot) | ~1.0 mg | Moderate impact

• Paper-filter drip/pour-over | ~0.2 mg | Very low impact

Five cups of French press per day raises LDL approximately 6 to 8% over 4 weeks. Paper-filtered coffee shows no significant LDL change. Paper filters trap over 90% of cafestol. Switching from French press to paper filter is one of the simplest cholesterol interventions that exists. If you can’t give up your French press: pour the finished coffee through a paper filter before drinking. Problem solved with an extra 30 seconds.

My Cup

I make my morning coffee work hard…I’ve just found it’s the easiest way to shove a bunch of important things in one place efficiently. Here’s my exact morning coffee, since people always ask. (, you can skip ahead, nothing has changed)

The coffee: Paper-filtered, freshly ground whole bean (organic, lab-tested). The paper filter is non-negotiable for me because of the cafestol-LDL thing.

What goes in it:

• 1 TBSP unsweetened cocoa powder (I use CocoaVia). Cocoa is loaded with flavanols, but the heavy metals concern is real. CocoaVia has consistently low levels, which is why I chose it. (Discount for you on Cocovia | Also sold on Amazon)

• 10g creatine. I use DoNotAge’s Creatine, pure high-quality creatine monohydrate (10% off with code: YBM). For more on creatine, read this.

• Collagen peptides. Vital Proteins travel packs for on the go. At home, Pure Therapro Rx Tripeptide Plus.

The method: Everything gets whisked with an electric whisk.

Sounds like a production, but it takes me less than a minute to put it all together. I drink it immediately to max out the polyphenol percentage.

In Case You Skimmed

• Coffee is associated with approximately 1.8 years of added healthy life expectancy, based on 50+ international studies. The sweet spot is 3 to 5 cups per day.

• Benefits hold for caffeinated and decaf for most outcomes, pointing to polyphenols as a key driver. Drink freshly ground coffee within 30 minutes for maximum polyphenol benefits.

• Caffeine activates AMPK, the same cellular energy pathway triggered by fasting and exercise. Moderate coffee drinkers show telomere lengths comparable to people 5 years younger.

• Coffee’s strongest organ data is the liver: 29% lower fatty liver risk, 39% less cirrhosis, 40% less liver cancer.

• Type 2 diabetes risk drops about 6% per cup...but adding sweeteners and creamers eliminates this entirely.

• A 2026 Harvard study of 131,821 people found 18% lower dementia risk with 2 to 3 cups of caffeinated coffee daily.

• Coffee shows positive effects on heart rhythm: 40% lower AFib recurrence in coffee drinkers vs. abstainers.

• Morning-only drinkers had 31% lower cardiovascular mortality compared to all-day drinkers.

• Cafestol in unfiltered coffee raises LDL. Paper filters remove over 90% of it.

• Black coffee does not break a fast and may enhance fasting-related autophagy.

After reviewing 26 studies, my professional conclusion is that I need to drink more coffee. Science said so.

This week, look at what’s going into your cup. If you’re drinking it through a paper filter, black or close to it, and before noon...you’re already doing this right, if not, you know what to do. See how your energy, your sleep, and your morning ritual feel by next Monday.

See you then,
Susan

Longevity in the Wild

A friend of mine recently went through a kitchen renovation. For six weeks, no stove, no counter space, no routine. When her kitchen was finally done, she stood in it for a full minute before she even turned anything on. She said she didn’t realize how much the ritual of making her coffee mattered. I think about this with my morning coffee setup. People look at the creatine and the collagen and the cocoa powder neatly placed next to the coffeemaker and think it’s complicated. But those few minutes every morning set my whole day up for success. It’s a practice, not a chore.

“I keep getting served NAD ads on Instagram; what does it even do?” — three friends this week.

These days, it feels like everyone’s selling you an NAD+ supplement, but almost nobody actually stops to explain what it is, why you’re losing it, why you even have it in the first place, what it does, or which version actually works. (I’ve tried nearly all of them, don’t worry, we’ll get to that)

NAD+ might be the most talked-about molecule in longevity that almost nobody can actually explain. I know this because I work in this space, I’ve tried many NAD+ products, and when someone asks me “so what should I take?”...my honest answer is longer than they want it to be.

So instead of just telling you what I take (I’ll get there), I want to do something most of these supplement companies skip entirely: explain what NAD+ actually is, why it declines, what that decline feels like, and why the delivery method might matter most.

What NAD+ Is

Nicotinamide adenine dinucleotide. If that doesn’t roll off the tongue, just know this: NAD+ is a coenzyme (a non-protein organic molecule that helps in biochemical reactions) that exists in every single cell of your body, and without it, those cells can’t produce energy.

Your mitochondria (the tiny power plants inside your cells) use NAD+ to convert food into ATP, which is the energy currency your body runs on. No NAD+, no ATP. No ATP, no you.

Think of NAD+ like your phone's battery. When you're young, you wake up at 100% every day and it holds a charge no matter what you throw at it. By your 40s, you're waking up at 60%, and it's draining faster than you can top it off. The phone still works...just slower, dimmer, and it dies at the worst possible time.

But energy production is just the beginning. NAD+ also fuels three critical systems that keep your cells functioning:

Sirtuins (SIRT1 through SIRT7): These are NAD+-dependent enzymes that regulate metabolism, stress responses, DNA repair, and gene expression. Think of them as your cells’ maintenance crew. They can’t clock in without NAD+. Sirtuins are also the enzymes that get activated during fasting and caloric restriction, which is part of why those interventions show up in longevity conversations so consistently.

PARPs (Poly-ADP-Ribose Polymerases): These are your DNA repair enzymes. When your DNA breaks (and it breaks constantly; thousands of times a day), PARPs detect the damage and initiate the fix. They also run on NAD+. The catch: when DNA damage is chronic (from inflammation, poor sleep, UV exposure, or just...(sigh) aging), PARPs go into overdrive and start draining your NAD+ supply faster than your body can replenish it.

CD38: CD38 is an enzyme whose primary job is to consume NAD+. It cleaves it apart. And here’s the kicker...CD38 activity increases as you age. Like…significantly. It’s driven up by inflammation, and it’s accused of being the single biggest reason your NAD+ levels drop over time. CD38 can also degrade NMN directly (a popular NAD+ supplement precursor), which means it can intercept your supplement before it ever becomes NAD+. (Hang on, we’ll get to supplements)

In plain English: NAD+ is the molecule your cells need to make energy, repair DNA, and keep the lights on. Three major systems compete for it, and one of them (CD38) gets hungrier the older you get.

There’s one more thing worth knowing: NAD+ levels oscillate with your circadian rhythm. The enzyme that recycles NAD+ (called NAMPT) is directly tied to your internal clock. Disrupted sleep patterns lower NAD+ levels. So yes, your sleep habits are part of this equation.

When NAD+ Peaks, When It Drops, and What That Feels Like

NAD+ levels are highest in youth. They start declining meaningfully in your 30s and by your 40s and 50s, you may have roughly half the NAD+ you had in your 20s. In skin tissue specifically, the decline can be 50% or more over an adult lifespan.

The decline isn’t just a function of passing years; several things accelerate it simultaneously:

• CD38 ramps up with age and inflammation. Senescent cells (the “zombie cells”) release inflammatory signals that drive CD38 expression in neighboring cells. More inflammation, more CD38, less NAD+. It’s a feed-forward loop.

• DNA damage accumulates. More damage means more PARP activation, which means more NAD+ consumed for repair. In human skin, PARP activity significantly increases with age and inversely correlates with NAD+ levels.

• NAMPT declines. This is the rate-limiting enzyme in NAD+ recycling (the salvage pathway that produces about 90% of your NAD+). Less NAMPT means slower recycling.

• Mitochondrial dysfunction creates a vicious cycle. Low NAD+ impairs SIRT3 (the mitochondrial sirtuin), which worsens mitochondrial function, which generates more reactive oxygen species, which damages more DNA, which activates more PARPs. Around and around it goes.

So what does this actually feel like? Probably familiar:

Fatigue that sleep doesn’t fully fix. Slower recovery from workouts. Brain fog that shows up in the afternoon and doesn’t leave. Injuries that used to heal in a week now taking three. Skin that looks tired even when you’re not. That general sense of “I used to bounce back faster” that we write off as just getting older.

Not all of that is NAD+ alone, obviously. But the overlap between “things people complain about starting in their late 30s and 40s” and “things that happen when cellular NAD+ drops” is...striking.

In plain English: NAD+ peaks when you’re young and declines steadily from your 30s onward. The drop is driven by inflammation, DNA damage, and an enzyme (CD38) that literally eats your supply. What it feels like is the slow erosion of energy, recovery, and resilience that most of us chalk up to “aging.”

Before You Reach for a Supplement, The Dietary Building Blocks

Your body makes NAD+ from raw materials in food, primarily through two routes. The first is vitamin B3 (niacin and niacinamide), found in high concentrations in poultry, fish, beef, mushrooms, lentils, and whole grains. A single chicken breast or a cup of crimini mushrooms gets you close to your daily B3 requirement (16 mg for men, 14 mg for women).

The second route is the amino acid tryptophan, which your liver converts to NAD+ through the kynurenine pathway. About 60 mg of tryptophan yields the equivalent of 1 mg of niacin. Turkey, eggs, cheese, tofu, and edamame are all solid tryptophan sources.

There are also trace amounts of NMN in foods like broccoli, avocado, and edamame, but we’re talking fractions of a milligram per serving...so, not therapeutic. The bottom line is that a protein-rich diet with plenty of B vitamins gives your body the raw materials it needs to keep the NAD+ production lines running.

It just can’t outpace the decline once CD38, PARPs, and NNMT start pulling ahead.

How Do You Know If You Need to Supplement It?

Unfortunately, there’s no standard blood test for NAD+ that your doctor can order through Quest or LabCorp. It’s not on any routine panel. Jinfiniti Precision Medicine offers the first at-home intracellular NAD+ test (CLIA-certified, measures NAD+ inside your blood cells rather than floating in serum), and they process the vast majority of NAD+ tests worldwide. It runs about $200 per test.

But even Jinfiniti’s test has a limitation: it measures NAD+ in white blood cells. Whether that accurately reflects what’s happening in your muscles, brain, liver, and heart (where the aging biology actually plays out) is still an open question.

I’ll save you $200 and say the practical answer is that if you’re over 35 (40 if you’ve lived a very healthy life) and experiencing the symptoms I just described, your NAD+ levels have almost certainly started to decline. That’s not a guess; that’s what the population data consistently shows across multiple tissue types.

The trickier question is what to do about it, because here’s the catch that sets up the rest of this post: raising NAD+ in your blood is relatively easy. Several supplements can do that reliably. Getting NAD+ into your actual cells, especially skeletal muscle...that’s a different story entirely.

The Precursor Supplement Problem

Here’s the thing: you can’t just take NAD+ as a supplement and have it work. The molecule is too large and too electrically charged to cross cell membranes. For you molecular biology geeks out there: it has two negatively charged phosphate groups and a molecular weight roughly twice that of its precursors. Total no-go.

So almost every NAD+ supplement on the market is actually a precursor: a smaller molecule that your body can absorb and then convert into NAD+ once it’s inside the cell. The question is which precursor (there are many), and whether it actually gets where it needs to go.

The main players:

NR (Nicotinamide Riboside) is the most clinically studied NAD+ supplement on the market with over 35 human trials. It enters cells via nucleoside transporters and gets converted to NMN, then to NAD+. NR doesn’t cause flushing, it’s well-tolerated up to 3,000 mg/day, and it reliably raises blood NAD+ levels by about 60% at standard doses.

NMN (Nicotinamide Mononucleotide) is the precursor David Sinclair made famous, and on paper it makes the most compelling case. It's one enzymatic step closer to NAD+ than NR, so why not skip ahead? Because Charles Brenner, the scientist who discovered the NR pathway, argues that NMN can't actually cross your cell membranes. Your body has to strip it back down to NR before it can get inside the cell, then rebuild it into NMN again once it's in. So you're going for the express train, but your body's putting you back on the local. But not so fast, some research suggests cells may have a specific NMN transporter (SLC12A8), meaning NMN can enter cells directly. To add even more intrigue, the FDA has recently categorized NMN as a pharmaceutical compound. NR did not get that scrutiny. No one disputes the increased NAD+ blood levels seen from regular use of NMN; it’s the efficiency and mechanism that are up for debate.

Niacin (Nicotinic Acid) is the original vitamin B3, available at any pharmacy for pennies. It’s actually the most efficient NAD+ booster for the liver. But it causes the famous “niacin flush” (intense skin redness and tingling from prostaglandin release), which most people hate enough to stop taking it.

NAM (Nicotinamide/Niacinamide) is the other form of B3. No flushing. Cheap. But it directly inhibits sirtuins (the very enzymes you’re trying to activate by raising NAD+), which creates a frustrating paradox: more NAD+ in the tank, but the maintenance crew is on a forced break.

Now here’s where it gets really interesting. A landmark 2026 study from Nestlé and Nature Metabolism put NR, NMN, and NAM head-to-head for the first time in 65 healthy adults. Both NR and NMN approximately doubled blood NAD+ over 14 days. They were statistically equivalent. NAM barely moved the needle.

But the bigger finding was how NR and NMN actually work. The researchers discovered that gut bacteria rapidly break down both NR and NMN into plain nicotinamide, which then gets converted to nicotinic acid (niacin) by the microbiome. It may be that gut-derived niacin is what’s actually driving the blood NAD+ increase for both supplements. Which raises the question of whether you even need the expensive versions.

And then there’s the quality problem. A March 2025 ChromaDex study tested 38 commercial NR supplements. Only 13% met their label claims. 36% contained virtually no NR at all; nine products had zero detectable NR. The brands that passed: Tru Niagen, Elysium, Thorne, Genuine Purity, and Probase Nutrition.

On top of that, a key finding keeps showing up in clinical trials: blood NAD+ goes up with supplementation, but skeletal muscle NAD+ often doesn’t. The gap between what your lab numbers say and what your muscles actually experience is one of the biggest unresolved questions in this space.

The Delivery Methods: I’ve Tried (Almost) All of Them

I’ve been on the NAD+ train for a while now, and here’s what I found, ranked from theoretical worst to best (in my opinion).

NAD+ IV Drips: The One I Skipped

I’ve never done an NAD+ IV, and after everything I’ve learned, I’m glad I didn’t. Here’s why…

NAD+ is too large to cross cell membranes; when you infuse it directly into the bloodstream, it stays extracellular (outside). Your body treats that flood of extracellular NAD+ as a danger signal. Literally. Research published in Frontiers in Immunology has shown that extracellular NAD+ functions as a DAMP (damage-associated molecular pattern), activating purinergic receptors (how cells talk to each other) and triggering an inflammatory immune response. Your body thinks tissue is damaged and races to repair it.

That’s why NAD+ IVs are famously miserable. Every participant in a 2026 Frontiers in Aging study comparing NAD+ IV to NR IV reported moderate-to-severe abdominal cramping, nausea, vomiting, increased heart rate, and chest pressure during infusion. Sessions take 2 to 4 hours because you can’t push the drip faster without making symptoms worse. And about 70% of recipients showed a 3 to 10-fold spike in hs-CRP (an inflammation marker) afterward.

Adding insult to injury, a pilot study found that NAD+ IV didn’t even raise blood NAD+ meaningfully until 24 hours later, and then only by about 2%. Meanwhile, Dr. Eric Verdin, CEO of the Buck Institute for Research on Aging, has said that IV NAD+ is “mostly broken down into nicotinamide” before reaching cells, and you can buy nicotinamide for way less than a fancy IV.

I’ve seen anywhere from $600 to $1,000 per session to sit in a chair for three or four hours feeling terrible, triggering an inflammatory response, and getting something your body immediately dismantles into a molecule that costs five cents.

NAD+ Injections: My Personal Nightmare

I tried NAD+ injections. My entire body went hot. I got an uncomfortable, full-body ache that I can only describe as feeling like every cell was angry at me simultaneously. It was bad, and I hated it. And yes, this was sourced by my longevity doctor in compounded prescription form.

At the time I didn’t understand why. Now I do. Same mechanism as the IV: you’re flooding your bloodstream with a large molecule your body interprets as a danger signal. The heat and ache were my immune system responding to what it perceived as tissue damage. And I didn’t notice any energy benefit. None. Hard pass on this one.

Patches: Nothing

I tried NAD+ patches. I didn’t notice a thing. In fairness to me, the science backs this up. NAD+ has a molecular weight of about 663 daltons; the general rule for passive transdermal penetration is that molecules over 500 daltons don’t cross intact skin. There are zero peer-reviewed human clinical trials showing patches raise blood NAD+ levels. The marketing claims aren’t supported by published data. I don’t even remember which brand I tried, but it’s a moot point, isnt it.

NAD+ Nasal Spray: The One I Made My Sister Try

I didn’t try this one myself, but I made my sister the guinea pig. The theory is sound on paper: the nasal mucosa is highly vascular, so spraying NAD+ into your nose bypasses the digestive system and first-pass liver metabolism entirely. Some researchers believe the nasal route may also offer direct brain access via the olfactory nerve pathway, which would make it uniquely interesting for cognitive symptoms specifically. Note that this is by prescription only. Please do not buy this version off the internet.

My sister’s report: when she remembered to use it consistently, her brain fog improved noticeably (yes, I see the irony). The science on intranasal NAD+ in humans is still in progress, but so far most of the cognitive benefit data comes from preclinical models showing NAD+ reduces neuroinflammation and improves learning and memory. Maybe with prolonged use she’d remember to use it!

NR: Solid Science, Subtle Results, Will Test Again

NR is the most researched NAD+ precursor on the market. 35+ human trials. Clearly safe at doses up to 3,000 mg per day. It reliably raises blood NAD+ by about 60%, and longer-term studies (4+ weeks) have shown it can even raise NAD+ in the brain.

I tried the gold standard brand, TruNiagen (created by the aforementioned Charles Brenner) recently…took it for about a month at the bottle’s recommended dose of 500mg. I didn’t notice a dramatic, obvious difference in how I felt day to day. That doesn’t mean it wasn’t doing something at the cellular level; blood NAD+ definitely goes up, the science is solid. But in terms of subjective energy, recovery, or anything I could point to and say “that’s the NR”...it was subtle at best. It’s worth noting that my NMN experience (coming up next) was at 1,000mg so maybe if I’d pushed it to a gram I would have felt more. Something I’ll probably revisit one of these days. Again, NR has one of the most studied safety profiles around, so if you’re looking to dip a toe into raising your NAD+ levels, this is a solid place to start.

NMN: Where This All Started for Me

NMN was actually my entry point into the whole NAD+ world. About five years ago, my longevity doctor put me on 1,000 mg a day; I suspect the dose came from David Sinclair’s recommendation. And honestly, it worked. I felt a noticeable lift in energy. So the debate above aside, my subjective experience on NMN at that dose was very real. Whether that was the NMN itself, or my gut bacteria converting it to niacin, or just the fact that I was flooding my system with enough precursor material to move the needle...I can’t say for sure, but I felt it.

I take Do Not Age’s Pure NMN (they also make an NR) because they are a research-focused formulation company whose compounds are also used by research labs. I trust the brand enough that I asked for a reader code: YBM takes 10% off. This is what I take when I’m off a 5-amino 1MQ cycle…keep reading for more on that. Sourcing of anything you ingest is important, but since NMN is classified as a pharmaceutical, it’s especially important here.

Niacin: The Surprise Skin Win

This one’s a bit sideways. In the summer and when traveling to warm places, I take Heliocare Advanced, which is a pill-form sunscreen…yes, that’s a real thing, and yes, it works. One of these Mondays I’ll do a post about skinspan. This product contains 300 mg of niacin along with a proprietary Fern-block compound. What I notice each time is that my skin starts glowing.

Niacin is the original, no-frills NAD+ precursor. Your liver converts it into NAD+, and it may actually be the molecule that NR and NMN ultimately get converted into by your gut bacteria. The downside is the famous niacin flush (skin redness and tingling), but at 300 mg in a formulated product, I didn’t experience it. What I did notice was visibly better skin, which makes sense because skin is one of the tissues where NAD+ decline is most dramatic (50%+ over a lifetime) and niacin is the most efficient liver-pathway NAD+ booster available. Shout out to my Brazilian dermatologist for this one.

5-Amino 1MQ: The Dark Horse

This is the one most people have never heard of, and it’s my favorite by a wide margin. 5-amino 1MQ isn’t an NAD+ precursor at all. It works through a completely different mechanism: instead of adding NAD+ precursors, 5-amino 1MQ blocks the enzyme (NNMT) that’s been draining your NAD+ supply in the first place.

Here’s how NNMT works: every time your body uses NAD+, one of the byproducts is nicotinamide (NAM). Normally, NAM gets recycled back into NAD+, but NNMT diverts NAM away from that recycling process by methylating it into a waste product (1-methylnicotinamide) that gets excreted. NNMT activity increases with age, particularly in fat and muscle tissue, which means your recycling system gets less efficient right when you need it most.

In plain English: Instead of pouring more water into a bathtub with the drain open, 5-amino 1MQ plugs the drain.

5-amino 1MQ also preserves SAM (S-adenosylmethionine), your body’s primary methyl donor, because NNMT competes for the same methyl groups. So you’re protecting two important metabolic resources with one compound. This is extremely valuable to people like me who have an MTHFR variant (80% of you reading this also have it, btw), and why taking creatine also helps. See this post for more on that.

But back to 5-amino 1MQ (it is a mouthful, isn’t it?)…I felt it immediately. And I mean immediately. Do not take this in the afternoon or you will not sleep. The first few days, the energy was almost overwhelming; like someone turned the voltage up on my entire system. It levels out after about 3 days, but the initial hit is unlike anything I’ve experienced from any other NAD+-related compound. And it wasn’t just me. Other people I know…subscriber and longevity aficionado , for one, described the same experience. Please note that we both sourced this through a longevity doctor through a compounding pharmacy. Also important to note: this one must be cycled. The most common recommendation is 4 to 6 weeks on, 2 to 4 weeks off. I spend longer in the off-cycle than the on-cycle, more like 3 months off. The idea is to prevent your body from adapting to the NNMT inhibition and to maintain sensitivity to the compound.

The science is early but compelling. A 2024 study in Scientific Reports found that 5-amino 1MQ improved grip strength in aged mice to a greater degree than vigorous exercise alone. When combined with exercise, the improvements were additive. Another study showed it to shorten muscle recovery time, increase intracellular NAD+ levels 1.2 to 1.6-fold, and reduce fat cell size by 30 to 40% without diet changes.

The caveat: there are no published human clinical trials. Zero. The mechanism is well-understood and well-published in journals like Frontiers in Pharmacology and Biochemical Pharmacology, but the human data just isn’t there yet. This is the same gap BPC-157 lives in (more on that here); compelling animal data, strong mechanism, real-world anecdotes, but no human studies. If that’s a dealbreaker for you, I understand. For me, the mechanism made sense, the preclinical data was solid, and the experience spoke for itself.

In Case You Skimmed

• NAD+ is the coenzyme every cell needs to make energy, repair DNA, and maintain itself. It declines starting in your 30s, accelerated by inflammation, DNA damage, and an enzyme called CD38 that literally consumes it.

• You can’t take NAD+ directly as a supplement; the molecule is too large to enter cells. Every “NAD+ supplement” is actually a precursor (NR, NMN, niacin) that your body converts.

• NR and NMN both raise blood NAD+ by about the same amount. A 2026 study found your gut bacteria may convert both into plain niacin before they do anything, which raises questions about whether the expensive versions are worth it.

• NAD+ IVs are expensive, miserable, trigger inflammation, and your body breaks the NAD+ down before it can enter cells. NAD+ injections gave me a full-body ache and did nothing for energy. Patches have zero clinical evidence.

• 5-amino 1MQ takes a different approach entirely: instead of adding more precursors, it blocks the enzyme (NNMT) that drains your existing NAD+. I felt the difference immediately and it’s the only NAD+-related compound that gave me an obvious, undeniable energy response.

• Quality matters. 87% of NR supplements tested in a 2025 audit failed to meet label claims. If you’re investing in NAD+ supplementation, buy from companies with third-party testing.

NAD+ supplementation isn’t a silver bullet, and the science is still catching up to the hype. But the biology is real, the decline is real, and for me, finding the right approach to supporting it has been one of the more noticeable changes in how I feel day to day. If you think NAD+ supplementation might work to improve your days, try out which method works best for you, and see how you feel by next Monday.

See you then,
Susan

Longevity In The Wild

A friend and subscriber (who shall remain nameless) recently admitted she takes her kids to McDonald’s more often than she’d like. I respect the honesty. I also warned her she was going to end up in this section.

The answer nobody wants to hear: meal prep. Even a little. Organic chicken nuggets in the freezer. An air fryer and a bag of potatoes with sea salt. Frozen fruit for smoothies. It doesn’t have to be a whole thing; it just has to be there so that when the 5 PM panic hits, the path of least resistance isn’t a drive-thru, it’s a freezer with a plan.

I love peptides. And, boy, are they finally having their moment. Actually, peptides are having a year. Ever since Ozempic taught 30 million Americans that injecting a synthetic peptide could change their bodies, the wellness world has been on a treasure hunt for the next one. And right now, the peptide getting the most attention isn’t FDA-approved, isn’t available at your pharmacy, and has never been tested in a proper human clinical trial.

Its name is BPC-157. The internet calls it the Wolverine peptide. And depending on who you ask, it’s either the most promising healing compound in a generation...or a gray-market gamble with unknown long-term consequences.

I’ve actually been using BPC-157 off and on for nearly five years...long before it became a household name. I started with the oral form, and about six months ago, after spraining my ACL and PCL, I switched to injectable, which I now swear by. The most noticeable difference for me is weight training recovery; not some overnight miracle, but meaningfully, consistently better.

I’m a believer. I’m also a believer in doing the homework, which is exactly why this compound deserves a closer look.

A Brief History of BPC-157

BPC stands for Body Protection Compound. The “157” refers to a specific 15-amino-acid fragment isolated from a larger protein found in human gastric juice. It was first characterized in the early 1990s by Dr. Predrag Sikiric and his team at the University of Zagreb in Croatia. They were studying the gut’s natural protective mechanisms and found that this particular peptide fragment had an unusually broad range of effects in animal models: healing tendons, protecting the stomach lining, reducing inflammation, even repairing nerve damage.

For more than a decade, BPC-157 lived in the bodybuilding underground. I always tell people: look to the Eastern European bodybuilding community, because they go way out of bounds, they figure out what works, and by the time it trickles down to us here in the US, it’s therapeutic grade and probably works well. That’s essentially what happened here. The research came out of Croatia, lifters on forums like Bodybuilding.com and ThinkSteroids started sourcing vials from overseas labs, and by 2018 there was a thriving Reddit community swapping dosing protocols. Serious athletes passed vials around like contraband, swearing it healed torn tendons and chronic injuries that nothing else could touch. The research stayed small and the audience stayed niche...until it didn’t.

Then came the perfect storm: Joe Rogan told his 20 million listeners it cured his elbow tendinitis in two weeks. Jeremy Renner credited peptide injections (including BPC-157) as part of his recovery after being crushed by a 14,000-pound snowplow. Men’s Health put it on the cover. And suddenly your dad’s golf buddy was asking his doctor about it.

What Does BPC-157 Actually Do?

The animal research paints a genuinely compelling picture. And while the human clinical data hasn’t caught up yet (more on that in a minute), the mechanisms help explain why so many people, myself included, swear by it.

But first, the thing that makes BPC-157 different from almost every other peptide out there: where it comes from.

Why This Peptide Works Orally (Most Don’t)

BPC-157 is derived from a protein naturally found in human gastric juice. Your stomach already makes a version of this. And that’s a big deal, because most peptides get destroyed by stomach acid the moment you swallow them (which is why things like insulin have to be injected; your gut would chew them up in minutes).

BPC-157 is the opposite. It’s remarkably stable in gastric juice (I know, eww); it stays intact for over 24 hours in the same acidic environment that breaks down standard growth factors in about 15 minutes.

In plain English: Your stomach was built to handle this compound.

This also explains why gut healing was the original use case. In animal studies, BPC-157 consistently protects and repairs the stomach lining, counteracts NSAID damage, heals ulcers, stabilizes tight junctions in leaky gut models, and even acts as what researchers call an “alcohol antagonist” against ethanol-induced lesions. The gut research is actually some of the strongest and most consistent in the BPC-157 literature.

But the effects go well beyond the gut. BPC-157 appears to work through several overlapping pathways:

Angiogenesis (new blood vessel formation): BPC-157 activates the VEGFR2 pathway, which tells your body to build new blood vessels. More blood flow means more oxygen, nutrients, and immune cells reaching damaged tissue. In chick embryo studies, it increased blood vessel formation by 129 to 152%.

In plain English: It helps your body build roads to the construction site so the repair crews can actually get there.

Growth hormone receptor upregulation: An independent study at Chang Gung University in Taiwan found that BPC-157 increased growth hormone receptor expression in tendon fibroblasts by up to 7-fold. When growth hormone was then added, cell proliferation increased synergistically.

In plain English: BPC-157 may turn up the volume on your tendon cells’ ability to hear and respond to growth signals.

Anti-inflammatory effects: It reduces TNF-alpha, IL-6, and COX-2 expression, and downregulates NF-kB signaling. These are the heavy hitters in the inflammation cascade.

In plain English: It dials down the alarm system so your body can stop panicking and start repairing.

Nitric oxide modulation: BPC-157 doesn’t just increase nitric oxide production; it appears to modulate it bidirectionally. It activates the Akt-eNOS pathway, which increases nitric oxide in blood vessel walls, causing them to dilate and deliver more oxygen and nutrients to injured tissue. But in animal models, it also counteracted both hypertension (from blocked NO) and hypotension (from excess NO). The peptide seems to push the system back toward balance rather than just cranking one dial.

In plain English: It reads the room. If your blood vessels need to open up, it helps them open. If they’re too dilated, it pulls them back.

Tissue-specific repair (a.k.a. why people actually use it): This is where it gets practical. In tendons and ligaments, BPC-157 activates the FAK-paxillin signaling pathway, which controls how cells attach, migrate, and survive. When you injure a tendon, fibroblasts (the cells that rebuild connective tissue) need to physically travel to the damage site and anchor themselves there to start laying down new collagen. BPC-157 increases the phosphorylation of both FAK and paxillin in those cells, essentially giving them better GPS and stronger grip. It also upregulates vinculin, which strengthens the structural scaffolding that cells use to pull themselves forward during migration.

In plain English: Your repair cells need to get to the injury, grab on, and start rebuilding. BPC-157 makes them better at all three.

In skeletal muscle, the same FAK-paxillin mechanism applies. After a muscle tear, satellite cells (your muscle stem cells) activate, migrate to the damaged area, and fuse with injured fibers to regenerate them. Studies show BPC-157 increased muscle cell migration by up to 76% in a dose-dependent manner. It also accelerates the re-establishment of myotendinous junctions (the point where muscle meets tendon), which is typically the weakest link after an injury.

For bone healing, BPC-157 stimulates osteoblast activity and angiogenesis within bone tissue, improving matrix deposition and fracture consolidation. In a 1999 rabbit study, BPC-157 healed segmental bone defects as effectively as an autologous bone graft, which is the gold standard in orthopedic surgery.

And then there’s the nervous system. BPC-157 stabilizes acetylcholine receptors at the neuromuscular junction and has reversed paralysis induced by neuromuscular blockers in animal models. It also normalizes dopamine, serotonin, and GABA signaling, which is relevant for nerve compression injuries and post-surgical numbness. In one spinal cord injury study, a single dose of BPC-157 reversed permanent tail paralysis in rats, and the effect held for a full year.

The “biological switch” concept: One of the most interesting findings from a 2025 review is that BPC-157 appears to activate multiple gene expression pathways within minutes of administration, including Akt1, VEGFR2, eNOS, and numerous growth factors, which then trigger cascading cellular processes that continue independently.

In plain English: BPC-157 acts as a biological switch that initiates self-sustaining healing programs rather than requiring continuous presence.

The Evidence Gap

The preclinical research is extensive and genuinely compelling. Over 200 published studies across more than 30 years show accelerated healing in tendons, ligaments, muscles, bones, gut tissue, and even spinal cord injuries in animal models. But there are exactly three published human studies, totaling fewer than 30 patients, with no control groups. Zero randomized controlled trials in humans...zero.

So why don’t we have better human data? The patent expired long ago, and no pharma company is spending hundreds of millions on trials for a compound they can’t own. The one company that tried (Pliva, in Croatia) got acquired twice and BPC-157 got buried.

Interestingly, the FDA banned it from compounding pharmacies in 2023 (but they may un-ban soon, stay tuned!), WADA banned it in 2022 (and WADA doesn’t typically bother banning things that don’t work), and political pressure to loosen peptide restrictions is growing while enforcement is essentially nonexistent. It’s basically available because of regulatory limbo.

In plain English: We have a mountain of animal evidence and a thimble of human evidence. That doesn’t mean it doesn’t work in humans (I can tell you from my own experience that something is working). It means the clinical science hasn’t caught up to what a lot of us are already seeing.

The Safety Conversation

Animal toxicology studies are genuinely reassuring. No lethal dose was ever identified. No teratogenic, genotoxic, or anaphylactic effects. The peptide appears remarkably well-tolerated in rats, mice, rabbits, and pigs. That safety profile is part of why I’ve been comfortable using it for five years.

That said, there are theoretical concerns I think you should be aware of:

• The cancer question. BPC-157 activates the FAK-paxillin pathway and stimulates angiogenesis (VEGF/VEGFR2). Both of those pathways are exploited by cancer cells to grow and spread. VEGF pathways are active in approximately half of human cancers. No study has shown BPC-157 causes cancer in animals or humans. But also, no study has examined long-term use in humans to rule it out, either. Some animal research actually suggests BPC-157 may suppress tumor growth, but the data is still too thin to draw any definitive conclusion.

  • Here’s what I think responsible use looks like: before starting BPC-157 (or any peptide, really), your doctor should be running baseline cancer markers. CEA antigen is a great one to start. And if your doctor isn’t offering this, you should be asking for it (that’s part of being your own advocate). It doesn’t eliminate the unknown, but it gives you a clearer picture of where you’re starting.

• The contamination issue. If you’re sourcing from the gray market, 30% of online peptides have been found to contain incorrect amino acid sequences. This isn’t a BPC-157 problem; it’s a sourcing problem. And it’s the single best argument for working with a physician who prescribes through a reputable compounding pharmacy.

  • I have only ever sourced this from reputable places. The oral form I used for years came from companies I vetted carefully; if you’re looking for a trusted oral option, I recommend LVLUP Health or Infiniwell. The injectable form I use is available by prescription only through my longevity doctor, who orders from a reputable compounding pharmacy with third-party testing.

In Case You Skimmed

• BPC-157 is a 15-amino-acid peptide fragment derived from human gastric juice. Your stomach already makes a version of it, which is why it’s one of the rare peptides that works orally.

• 200+ animal studies show it accelerates healing in tendons, muscles, gut, bones, and nerves through multiple pathways (angiogenesis, anti-inflammatory, nitric oxide modulation, and FAK-paxillin signaling).

• It has zero randomized controlled trials in humans. The animal science is compelling; the human science doesn’t exist yet.

• WADA banned it in 2022. They don’t ban things that don’t work.

• If you try it, sourcing is everything. Work with a physician, demand third-party testing, and don’t buy from the gray market.

I’m not going to make miraculous healing claims, but what I have experienced is better recovery from heavy bench sessions (for example), less lingering soreness, and a general sense that my body repairs itself the way it’s supposed to.

If you decide to try BPC-157, don’t expect to feel like Wolverine by Tuesday. But you might notice yourself recovering a little faster, feeling a little better, in a few Mondays.

See you then,
Susan

Longevity in the Wild

I’ve been trying to reframe lifestyle longevity for friends in terms of prescriptions. Like...if my doctor wrote me a prescription, I wouldn’t just not fill it. I wouldn’t say “eh, I’ll get to it next week.” I’d take it. So why would anyone treat the lifestyle non-negotiables any differently?

wrote a piece this week that made this click for me. She broke down the after-dinner walk, and it turns out the timing matters more than the effort. She explained it in more detail, but essentially, you/we/I have a 30-minute window after finishing a meal to catch the glucose spike before it peaks. Ten minutes of walking in that window produces a clinically meaningful insulin reduction. The same walk two hours later does not do the same thing.

Ten minutes, thirty-minute window to do it. That’s the prescription. The most powerful longevity interventions aren’t the ones that cost the most. They’re the ones you fill.

I love peptides. LOVE.

If there’s a molecule with plausible regenerative biology and a decent safety profile, I’m reading about it and probably ingesting or injecting it.

But not everything earns a permanent place in my rotation.

GHK-Cu did.

I started it because of a stubborn knee injury that had stalled. I managed to sprain my ACL and PCL and developed a Baker’s cyst in the process. Not catastrophic, but dramatic enough to require fluid aspiration and two cortisone injections just to calm things down.

The swelling improved. My knee did not.

For months after, the tightness lingered. That “something still isn’t right” feeling never resolved. Range of motion wasn’t where it should be. Stability felt slightly off. It wasn’t getting worse…but it wasn’t getting better either.

This wasn’t a patience issue; recovery had plateaued.

I was already using BPC-157 (we’ll spotlight that another Monday), but I wanted more repair signaling: more pathways, more coordination, something.

GHK-Cu had been on my radar for a different reason entirely: skin and hair biology. I’m skeptical of Botox and fillers for a whole host of reasons, so I’m always watching molecules that meaningfully improve skin. When I revisited the mechanism of how GHK-Cu works, it seemed like just the thing to help my knee. (Also, my longevity doctor told me it would help; my orthopedic knee guy laughed and told me it probably wouldn’t do anything. Mmmkay.)

What happened next was gradual but noticeable: range of motion improved, pain decreased, stability returned, that “off” feeling began to fade.

Could that have been time? Maybe…but time hadn’t done anything for months. The shift coincided with addition of GHK-Cu.

But before we get into benefits, forms, and how to use it, we need to back wayyyy up and talk about copper, what GHK-Cu actually is, how it works, and why this particular peptide gets to kick off the Younger By Monday Peptide Spotlight.

Why Copper Matters in the First Place

Copper is a trace mineral your body requires for a number of important functions. You don’t need much of it. But the little you need is absolutely critical.

Copper is required for enzymes that:

• Strengthen and stabilize collagen

• Help your mitochondria produce energy

• Support antioxidant defenses

• Assist in forming red blood cells

• Contribute to nervous system signaling

Copper has an active role in cell structure, energy, and protection.

You get copper naturally from foods like:

• Organ meats

• Shellfish

• Nuts and seeds

• Dark chocolate

• Legumes

Most people aren’t copper deficient. I’m going to guess it’s more dark chocolate than organ meats…it’s also found in many multi-vitamins and shakes like Momentum…which does bring up an important question…

Why Not Just Take Straight-Up Copper?

For you supplement-happy readers (of which I consider myself one), I must caution you that copper is one of those molecules that needs to be balanced.

Yes, copper helps strengthen collagen. Yes, it supports energy production. Yes, it participates in antioxidant defense. And why wouldn’t we want more of that?!

Well, the issue is that copper is also reactive. Free copper ions can generate oxidative stress if left free and unregulated.

Think of it like metal exposed to air and water. When iron oxidizes, you get rust. And when it’s uncontrolled, it causes structural damage.

Free copper behaves similarly inside the body.

That’s why your body keeps copper tightly regulated. In fact, there are special chaperones designed to escort copper throughout your body so that they are stored safely and rarely allowed to float freely.

But back to the balance part.

Copper and zinc act as partner minerals. They compete for absorption and influence each other’s levels.

Too much zinc can lower copper; too much copper can displace zinc. An imbalance can lead to oxidative stress, anemia, neurological symptoms, collagen abnormalities (gasp!). All to say that this is not a mineral to megadose casually.

Which is what makes GHK-Cu interesting…it doesn’t flood the body with copper; instead, it acts more like a courier than a supplement. I’ll explain.

What is GHK-Cu?

GHK-Cu is a peptide. Quick review: A peptide is a short chain of amino acids that sends signals telling your body to do things it already knows how to do, like repair, regulate, or rebuild.

The Cu part is copper. Easy.

The GHK part is more complex and more interesting. It’s a tripeptide made of glycyl-L-histidyl-L-lysine.

Let’s translate that.

First, the “L-.”

Amino acids, the building blocks of proteins, come in two mirror-image forms: L and D. Think about it like the left hand and the right hand. They look the same but aren’t interchangeable.

Your body uses the L-form almost exclusively when building proteins and peptides. So when you see L-histidine or L-lysine, it simply means this peptide is made from the naturally occurring version your body already recognizes.

Now the three amino acids:

1. Glycine (The Glycyl Part): The Flexible Foundation

Glycine is the smallest amino acid. Small but mighty! Because it’s small, it gives proteins flexibility, fitting into tight structural spaces that larger amino acids can’t. That tiny superpower matters enormously for collagen.

Collagen is the primary structural protein in tendons, ligaments, skin, and bone and follows a repeating pattern: glycine every third amino acid. Without glycine’s small size, the collagen triple helix literally cannot form correctly.

But glycine does more than that…it also helps calm your nervous system, acting as a calming neurotransmitter in your brain to balance overstimulation.

It’s also one of the key ingredients your body uses to make glutathione, one of your most important internal antioxidants. Glutathione helps neutralize oxidative stress, which builds up during injury, inflammation, and (sigh) aging.

Glycine is technically a non-essential amino acid (meaning your body makes it), but since it’s used so much, demand can exceed supply during stress or injury. (You see where I’m going with this in the context of my knee)

2. L-Histidine: The Copper Anchor

Histidine does the heavy biochemical lifting. It’s an essential amino acid, meaning we must get it from our diet (go protein!).

Histidine has a unique side chain called an imidazole ring. That ring is special because it acts as a ligand, (fancy term for electron donor) to bond with a metal ion…like, say, copper (Cu²⁺).

Basically, histidine has the right shape and electrical properties to hold onto copper, allowing it to be safely delivered where it’s needed. This is crucial.

3. L-Lysine: The Structural Reinforcer

Lysine is the muscle of the crew and is also an essential amino acid; you must get it from your diet protein. And it plays a disproportionately important role in connective tissue integrity.

Collagen is the main structural protein, but just making or taking collagen isn’t enough. It has to be reinforced.

Think of collagen like strands of rope. On their own, the strands are flexible. To make them strong, they have to be tied together. That tying process is called cross-linking.

An enzyme called lysyl oxidase does the tying, and…here’s the elegant part…it needs copper to work.

Without enough lysine or without proper cross-linking, collagen can still be made…but it’s weaker, less stable, less durable. (Which, yes, is exactly why I originally started looking into this for skin health.)

And lysine doesn’t stop there…it also has a role as a tiny switch inside cells. DNA is wrapped around proteins that contain lysine, changing those lysine “switches” changes how tightly DNA is packaged and whether certain instructions get read.

Lysine doesn’t just help build tissue, it helps decide what the cell does next.

Putting it all together:

• L-form → biologically recognizable

• Glycine → structural foundation

• Histidine → copper-binding activation

• Lysine → stabilization and repair

• Copper → collagen, energy, antioxidant defense.

Ta-dahhhh! GHK-Cu.

So after all that, you’re probably thinking: I NEED THIS! But here’s a nice surprise: your body already makes it.

It circulates in plasma. It’s present in saliva. It increases at injury sites. This is not some lab-created foreign molecule! It’s a repair signal your body makes and recognizes.

But…as with all wonderful molecules that we take for granted, levels decline significantly with age. And that decline tracks with something else we might notice: healing slows down.

How Does GHK-Cu “Know” Where to Go?

Injured tissue is chemically louder. When something is damaged or inflamed, the area has:

• More blood flow

• More cellular turnover

• More repair enzymes active

• More signaling molecules present

That environment makes repair pathways more “available.” GHK-Cu doesn’t seek out the injury; it simply interacts more where repair biology is already active. It’s actually always circulating everywhere, looking to be useful.

Is It Always “Needed”?

Your body is always repairing something. Collagen turns over constantly…DNA is continuously repaired…mitochondria are constantly maintained…so baseline repair signaling is always active.

But in times of injury, inflammation, or heavy tissue stress, demand increases.

What Happens If (by some miracle) It’s Not “Needed”?

It doesn’t just pile up. GHK-Cu has a relatively short half-live in circulation; we’re talking hours.

It’s eventually broken down by enzymes into its individual amino acids (glycine, histidine, lysine).

Those amino acids are then reused by the body like any others. So the peptide doesn’t linger indefinitely, it pulses through, participates in the repair, and it gets recycled for parts.

If Supplemented, Does Your Body Stop Making Its Own?

No! GHK-Cu isn’t replacing something that depends on feedback loops.

It’s a naturally occurring signaling peptide that your body makes in multiple tissues. There’s no strong evidence that short-term supplementation suppresses endogenous GHK production.

That said, chronic, indefinite use hasn’t been studied extensively. Which is why cycling on and off makes sense, because your body naturally pulses this particular repair signal. It basically goes in, repairs, does a mic drop, and peaces out.

Why This Makes Sense for Tendons (and skin, and bones, and…even lung tissue)

Connective tissue heals slowly because:

• Blood supply is limited

• Collagen turnover is slow

• Fibroblast activity is restrained

GHK-Cu rolls up and stimulates fibroblasts, increases type I collagen production, promotes angiogenesis (formation of new blood vessels), and improves extracellular matrix organization.

In plain English: it helps move out of “stalled” and back into “repair” mode.

That’s what made it an ideal choice for my knee…it needed a strong nudge.

Supplementation Administration

GHK-Cu can be used three main ways: topical, injectable, and oral. Let’s dive into each, because

Topical: The OG Use Case for Hair and Skin

Most of the human data on GHK-Cu is topical, meaning in cream or gel form. Studies show improved dermal thickness, collagen density, wound healing, and reduced wrinkle depth. To quote from this PubMed article:

“Based on cellular studies, undoubtedly, GHK can be considered as an anti-wrinkle ingredient.”

Applied directly to the skin, GHK-Cu has been shown to improve:

• Collagen density

• Skin thickness

• Elasticity

• Wound healing

Topical works well because you’re delivering the peptide exactly where collagen remodeling is happening. For deeper connective tissue, it likely doesn’t penetrate far enough.

I like Infiniwell’s GHK-Cu face cream and use it when I’m in an injectable off-cycle. I also like that it’s a closed pump delivery to protect it from oxidation.

And should you choose to stick to topical only, continuous use is considered fine; cycling on and off isn’t typically necessary. But that is not the case for the other two delivery methods.

Injectable (Subcutaneous - into your belly fat)

Subcutaneous injections in general avoid digestive breakdown and first-pass liver metabolism, which usually means more predictable exposure.

Injectable GHK-Cu delivers the peptide directly into circulation. This is the most direct way to get to tendons, ligaments, joint tissue, and be on hand for body-wide repair signaling.

This is the route typically used in regenerative or sports medicine contexts, and what I’m using for my knee. This must be prescribed from a physician from a reputable compounding pharmacy. Please do not buy this or any peptide off the internet.

And, either my knee is first in line, or systemic delivery behaves differently, but injectable GHK-Cu hasn’t matched the skin results I get from topical. For my purposes, though, it has worked wonders. Absolute magic.

About timing:

• Best cycled (4–8 weeks on, then a break) to mirror natural repair rhythms.

• If working out, best taken within an hour after the workout when your muscles and tendons are calling for backup; if not, best taken first thing in the morning.

• Pulse within the pulse: I inject Monday - Friday only and take the weekends off for an added bit of breathing room on the signal.

NOTE:

I should mention that injectable GHK-Cu is known to sting. As the nurse at my longevity doctor’s office told me (back when I was considering it just for skin), “Oh, you’ll know it’s there.” That’s actually why I avoided it for so long.

So imagine my surprise when I felt…nothing. Nothing. I genuinely questioned whether I’d injected it correctly or received a dud batch. But, neither. Vial after vial, nothing. This is not the typical experience…most people do feel a localized sting, so fair warning. That said, I’ve learned a few tricks over the years when it comes to injections. DM me. Also, it turns bright blue after reconstitution from white powdered form…it’s a bit unexpected, but now you know.

Oral: The Emerging Route

Most peptides (and all protein we ingest, really) are broken down in your digestive tract into their individual amino acids before they can enter circulation intact. While some peptides function better when taken orally, GHK-Cu does not seem to be one of them at first glance.

That said, lab-formulations attempt to protect the peptide in its intended form from degradation using advanced delivery systems.

Unfortunately, there is no strong sweeping data showing oral GHK-Cu is as effective as injectable, but if there is one brand I trust to have done the homework, it’s LVLUP’s version.

If you go this route, I’d advise you to cycle this one on and off, similarly to the injectable route, since it’s the same systemic exposure as the injected form.

Who Should Not Consider GHK-Cu

• Pregnant or breastfeeding women

• People with active cancer or copper metabolism disorders

• High-dose copper supplement users

• Anyone looking for overnight results (GHK-Cu supports repair biology; it is magic, but not in a disappearing act sort of way).

In Case You Skimmed

• GHK-Cu is a naturally occurring copper-binding peptide your body already makes.

• Its levels decline with age, coinciding with when healing starts to slow.

• Copper is critical for collagen strength, energy production, and antioxidant defense.

• GHK-Cu helps regulate repair signaling…especially collagen production and angiogenesis.

• It circulates everywhere, but becomes most relevant where tissue is actively repairing.

• It has a short half-life and is then broken down into reusable amino acids.

• Topical use is well studied (skin). Injectable is more direct for connective tissue. Oral is less predictable, but promising.

• GHK-Cu supplementation is not an overnight miracle; more like repair troop reinforcement.

If you’re looking to add more repair signaling into your world, I can say from experience that GHK-Cu is a compelling option.

Your body already makes it. And for many people, that may be enough. If that’s you, think of this post as a reminder of how elegant your biology already is…copper moving where it’s needed, collagen reinforcing itself, repair signals firing without you even thinking about it.

For me, my knee needed a little nudge…not more time, not more rest, not PT, just more repair signaling. And each Monday, it’s feeling a little better. If you’re struggling with a plateaued injury or noticing a wrinkle you’d like to soften, give it a whirl and see how you feel by the following Monday.

See you then,
Susan

Longevity in the Wild

A friend asked me this week: “Does the new foam protein at Starbucks actually count as protein?”

The fact that Starbucks has entered the protein game honestly thrills me. Coffee + protein on every corner? Elite convenience.

But there’s a catch: unless you get it unsweetened and unflavored, you’re getting about 20 grams of protein (win)…but up to 30–40 grams of sugar (major loss). At those sugar levels, it’s less protein drink and more dessert with great marketing.

We’ll tackle sugar soon (brace yourselves), but pairing protein with a blood sugar spike isn’t the metabolic win we’re going for here.

So YES! Get the cold foam. Just get it unsweetened, be boring; you’ll live (pun intended).

Stress gets blamed for everything.

Aging. Heart disease. Brain fog. Sleep problems. Inflammation.

And the research is clear: chronic stress is associated with accelerated aging and higher disease risk.

But stress also drives adaptation, the very mechanisms that make heat therapy, cold exposure, strength training, and a challenging crossword puzzle beneficial in the first place.

So here’s the real question: is stress the enemy or the teacher?

The answer is all about context, duration, and resolution.

Stress Is a Biological Asset

Our bodies are constantly trying to maintain stability in everything from temperature and blood pressure to blood sugar and oxygen levels. This is called homeostasis.

When something disrupts that balance (heat, cold, exertion, sickness, threat, uncertainty), your brain activates a response cascade that is…not to be dramatic, but…designed to keep you alive.

That cascade is coordinated by the autonomic nervous system, which has two main branches:

• Sympathetic → gas pedal (fight/flight/action)

• Parasympathetic → brake pedal (rest/digest/recover)

When disruption hits, the sympathetic branch slams the gas. And at the same time, it calls in backup.

That backup is the hypothalamic–pituitary–adrenal (HPA) axis: the hormonal arm of the stress response.

The hypothalamus sounds the alarm.
The pituitary sends the message.
The adrenal glands mobilize the troops.

They release:

• Adrenaline → heart rate up, blood pressure up, muscles ready

• Norepinephrine → focus sharpened

• Cortisol → fuel unlocked, nonessential systems paused

In plain English: for a brief biological moment, you are a Daft Punk chorus. Harder, Better, Faster, Stronger.

And in the short term, that’s brilliant, but stress physiology is meant to be cyclical:

Activate → Respond → Return to baseline.

When activation becomes chronic, cortisol lingers, blood pressure stays elevated, glucose regulation shifts, inflammation smolders. Over time, this cumulative burden becomes what’s known as allostatic load, the wear and tear linked to disease and mortality.

Stress is really two sides of the same coin: the same mechanism that builds resilience can accelerate aging…but only if it never powers down.

Stress Through a Longevity Lens

In longevity science, stress is not bad; it’s rehearsal.

Brief, controlled stressors (exercise, sauna, cold exposure) are associated with health benefits precisely because they activate stress pathways.

Acute stressors trigger adaptive signaling:

• Hormesis pathways (to make future stress less of a big deal)

• Heat shock proteins (which have a whole host of benefits)

• Mitochondrial biogenesis (making new cell powerhouses)

• Improved autonomic flexibility (ability to spike and recovery better)

Here’s what counts as longevity-promoting stress:

• A heavy lift in the gym

• A sauna session that raises core temperature

• A cold plunge that spikes norepinephrine

• A challenging but resolved conversation

• Concentrated mental effort that ends in clarity

Short stressors, followed by recovery.

Acute stress + recovery = adaptation

Chronic Stress: A Slow Erosion

This kind of stress keeps the gas pedal pressed. Oh, you’re going somewhere, but nowhere good. It’s linked to inflammation, metabolic dysfunction, and accelerated aging.

Over time, chronic stress can affect nearly every system in the body:

• Elevated resting heart rate

• Higher blood pressure

• Increased systemic inflammation

• Insulin resistance and visceral fat accumulation

• Disrupted sleep architecture (less deep and REM sleep)

• Suppressed immune function

• Impaired digestion and gut motility

• Hormone disruption (thyroid, reproductive hormones)

• Reduced heart rate variability (lower autonomic flexibility)

• Increased risk of cardiovascular disease

Here’s what chronic stress feels like:

• Waking up tired

• Feeling reactive instead of grounded

• Never fully switching off

• Jaw clenching or tight shoulders

• Shallow breathing

• Trouble sleeping

• Midday crashes

• Sugar or caffeine cravings

• Low-grade anxiety that never fully resolves

None of these feel overly dramatic. That’s part of the problem.

Chronic stress + no recovery = erosion

The ability to switch off to return to baseline is the marker of longevity.

The Hormesis Sweet Spot

The stressors that build resilience share three features:

✔ They are short
✔ They have a clear on/off
✔ They are followed by recovery

Heat, cold, exercise, difficult conversations…

Last week in Longevity in the Wild, I mentioned my friend’s observation of her college students who are so conflict-averse, they won’t send back the wrong order at a restaurant. It sounds trivial, but low-stakes confrontation is a form of stress exposure. The heart rate rises slightly, adrenaline flickers…and then, ideally, resolves. That resolution is the training.

Stress Inoculation

There’s a concept in psychology and physiology called stress inoculation.

The idea is simple: controlled exposure to manageable stress can improve your ability to handle future stress. It’s why it now takes me 40 minutes to start sweating in an infrared sauna, for example.

You can also think of it a bit like a vaccine. A vaccine doesn’t eliminate pathogens from the world. It gives your immune system a safe, contained exposure so it can practice responding without being overwhelmed.

Acute stress can work the same way.

When you regularly expose yourself to:

• Physical exertion

• Heat

• Cold

• Cognitive challenge

• Controlled discomfort

…your nervous system learns the pattern.

Spike. Mobilize. Recover. Safe again.

For example:

During intense exercise, heart rate surges, and blood pressure spikes. If a researcher were to measure your metrics mid-workout without context, they might send for the EMTs.

And yet, over time, regular physical stress improves:

• Resting heart rate

• Blood pressure regulation

• Vascular elasticity

• Insulin sensitivity

• Heart rate variability

A controlled spike builds a stronger baseline. That’s hormesis in action. The stress looks alarming in the moment, but it’s protective over time.

In plain English: your baseline tolerance for stress rises after your system has rehearsed.

And like with anything, practice makes progress. Stress obviously doesn’t disappear from life, but your response to it can change.

Stress You Don’t Choose

Of course, not all stress is voluntary.

Flights get delayed, schedules change, kids get sick, you get sick, markets wobble, someone cuts you off in traffic. What else…environmental toxins, noise, unpredictability, time zone shifts…

…all activate the same biological cascade.

You don’t control the disruption, but you can train your response.

Switching Off

Longevity isn’t about avoiding sympathetic activation; it’s about being able to return to parasympathetic mode.

Slow breathing, especially longer exhales, stimulates the vagus nerve and improves autonomic balance.

• Heart rate drops.

• Blood pressure settles.

• Cortisol signaling decreases.

You can consciously initiate recovery. Give it a whirl.

More Tools That Help Turn Stress Off

Breathing isn’t the only lever. There are a few supplements and behaviors that can help:

Magnesium (glycinate or threonate): Supports nervous system regulation and sleep. Many people are low.

Omega-3s (EPA/DHA): Help reduce inflammation and may blunt stress-related cortisol spikes.

Ashwagandha: An adaptogen shown in some trials to lower perceived stress and cortisol.

L-theanine: Promotes calm alertness without sedation.

Low-intensity movement (walking, yoga, light cycling): Clears stress hormones and shifts you toward parasympathetic tone.

Sleep: The ultimate reset. Nothing regulates stress physiology like deep sleep. Go to bed earlier.

Time outdoors: Lowers sympathetic activation and improve recovery signaling. Forest bathing is the fancy term for it; morning sunlight is the most powerful.

In Case You Skimmed

• Stress itself isn’t the villain; stress that never turns off is.

• Your body is built to handle short bursts of stress…that’s how it gets stronger.

• Exercise, sauna, cold, hard conversations…these are useful only if you recover afterward.

• Chronic low-grade stress (rumination, tension, constant notifications) is what ages you.

• The goal isn’t zero stress. It’s a nervous system that can switch gears.

• If you can spike and then settle, you’re building resilience.

• Pattern matters more than intensity.

This week, choose one acute stressor…something that pushes you slightly out of comfort like a heavy lift, focused effort, sauna, cold rinse (heck, maybe even send back the salad), then let yourself recover. And maybe do it again. See if you notice a difference in how you carry your tension by next Monday.

See you then,
Susan

Longevity in the Wild

This week’s completely unscientific but deeply satisfying discovery: if you chop up pre-cooked chicken and air fry it at 400° for about 10–11 minutes, it becomes crispy and elite, without losing its protein content. Heat denatures protein (changes its shape), but it doesn’t make it disappear. Mostly you’re evaporating water and triggering the Maillard reaction: the chemical reaction between amino acids and sugars that creates browning, flavor, and that deeply satisfying crisp edge. It’s not burning. It’s chemistry. In fact, as moisture cooks off, the protein becomes slightly more concentrated per gram. So yes, your air-fried chicken “protein croutons” are still doing their job. Throw them in a salad. Have them as a snack. Longevity, but crunchy.

Cold plunges went from ancient ritual to stainless steel status symbol in about five minutes.

Somewhere along the way, stepping into freezing water became proof of discipline, grit, and possibly moral superiority. If you’re not voluntarily shivering before sunrise, are you even optimizing?

Cold exposure isn’t new. It is, however, a real physiological stressor with measurable effects on the nervous system, metabolism, and mood. The question isn’t whether cold “works.” The question is what it does and how it can contribute to a positive outcome for you.

Discomfort is really having a marketing renaissance, and usually, when something gets loud, it’s worth getting curious.

A Brief History of Voluntary Freezing

Humans have been exposing themselves to cold on purpose for centuries.

Scandinavians alternate sauna with frozen lake dips. Russians pair banyas with snow rolls. Japanese practitioners perform ritual purification in cold waterfalls. Cold was originally cultural, spiritual, seasonal.

Modern cold, however, has an excellent brand manager.

His name is Wim Hof, the self-described “Iceman” who popularized the combination of cold immersion and controlled hyperventilation breathing, and even opened an ice bath class boutique in, of all places, Miami. His demonstrations such as climbing mountains in shorts and submerging in ice for record durations have brought laboratory attention to what had previously been folklore.

Studies of the Wim Hof Method showed that trained participants could influence stress hormones and inflammatory responses through breathwork and cold exposure combined. It was compelling.

Quick safety note: never practice hyperventilation breathing in water. Loss of consciousness risk is real.

The Scientists’ Take

While Wim Hof brought spectacle, researchers brought structure.

One of the most grounded voices in this space is Dr. Susanna Søberg, whose research focuses on how cold and heat exposure influence metabolism, brown fat activity, and insulin sensitivity.

Her findings are refreshingly sane.

In controlled studies, participants who practiced regular moderate cold exposure (11–15°C/52–59°F) showed:

• Increased brown fat activity

• Improvements in insulin sensitivity

• Enhanced metabolic flexibility

From that research came what she calls the Søberg Principle: 11 minutes of deliberate cold exposure per week, ideally divided into 2–3 sessions.

Just enough to signal adaptation.

A Personal Note

I have access to a cold plunge set to 51°F. Yes, I use it. Sometimes regularly. Always first thing in the morning. I used to brag I could stay in for 12 minutes.

Let me explain myself. If you’ve done a cold plunge, you’ll know that around minute three, something flips. The initial shock fades. Your skin goes numb. Your breathing steadies. Time becomes theoretical. Technically, you could stay in longer if you had nowhere to be and a weird curiosity about hypothermia.

Turns out, though, cold exposure isn’t about endurance; it’s about delivering a stress signal and letting the body do what it does once the signal is sent. 12 is not superior to four. I have thusly retired from competitive staying-in.

Why Cold Works

Cold exposure is primarily a nervous system event. When you enter cold water:

• Blood vessels constrict

• Heart rate increases

• Blood pressure rises

• The sympathetic nervous system activates

• Norepinephrine surges

• Dopamine increases significantly

That dopamine bump isn’t trivial. In controlled settings, cold exposure has been shown to elevate dopamine to 2–2.5× baseline. That’s why people report feeling energized, clear, and oddly happy after a plunge.

Cold activates you.

This is also why most people prefer cold in the morning. A later in the day ice bath is like sending a text in ALL CAPS to your nervous system out of the blue...jarring.

But wait, there’s more! There are benefits beyond the plunge. Once you leave the water, your body rapidly shifts into active rewarming mode. Blood vessels that just constricted begin to dilate again. Circulation increases. Core temperature is restored. Brown fat activates to generate heat through non-shivering thermogenesis. Catecholamine levels gradually settle. The nervous system moves from sympathetic spike toward recalibration.

That rebound costs energy, and energy = calories expended. If you allow your body to warm itself up, instead of immediately jumping into a hot shower or wrapping yourself in three blankets, you’ll extend that thermogenic window.

Mild shivering can significantly increase metabolic rate in the short term. Non-shivering thermogenesis (the brown fat portion) increases energy expenditure more subtly but more efficiently. You get two for the price of one.

Cold works because the body is good at restoring equilibrium, and that is where the magic happens.

What is Brown Fat?

Cold exposure is often marketed as a “fat-burning hack” because it activates brown adipose tissue (brown fat). White fat (like the kind you can pinch on yourself) stores energy. Brown fat burns energy.

Brown fat is rich in mitochondria, the same cellular powerhouses we care about for longevity.

Adults have less brown fat than babies, but they still have some; especially around the neck and upper back. Repeated cold exposure can increase brown fat activity and, in some cases, volume. Dr. Søberg’s research suggests regular cold may support metabolic flexibility, the ability to switch efficiently between burning carbohydrates and fat.

The calorie burn from brown fat activation is modest. This is not a weight-loss miracle, but it is helpful.

Cold Plunge vs. Cold Shower vs. Cryotherapy

Cold is cold, but not all cold delivers the same physiology:

Cold plunge (water immersion)
→ Rapid and deep core temperature drop
→ Strong cardiovascular + nervous response

Cold shower
→ Less intense, less uniform
→ Great accessibility and still effective

Cryotherapy chambers
→ Extremely cold air (e.g., −200°F)
→ Short durations (2–3 min)
→ Smaller core temperature change than water immersion

Cold water immersion is physiologically more potent that the other options, but like all things, the best one is the one you will do.

Long-Term Cold Water Swimming Studies

You might be thinking, but what about those people who do cold exposure habitually, like open-water cold swimmers?

Yes, they are a great group to study because they are doing it anyway, and some, for decades. Long-term observational studies on winter swimmers show:

• Lower baseline inflammation compared with non-swimmers

• Improved markers of stress resilience

• Evidence of higher brown fat activity

• Reported improvements in mood and sleep quality

Many cold water swimmers fully submerge, which means they’re also triggering the mammalian dive reflex: an involuntary response that slows our heart rates while increasing our blood pressure.

In cold-adapted swimmers, research suggests:

• The heart rate drop becomes more controlled

• Blood pressure spikes may become less extreme

• The sympathetic surge is more even keel

• The overall response becomes more predictable

In other words, their nervous system learns the pattern.

But that doesn’t mean it’s automatically beneficial for everyone. With repeated exposure, trained swimmers may experience a more controlled version of that response. For others, especially those prone to dizziness, it can make you dizzy and disoriented.

Remember, this is a self-selected group who tolerate cold well to begin with, so if you’re thinking of taking up a new hobby, please think about your own tolerance prior.

And allow me to put your brain at ease: you don’t need to dunk your head to get the metabolic or dopamine effects of cold exposure. Body immersion is enough.

Cold and Recovery: Not So Fast

Cold plunges are often sold as the ultimate recovery tool…the faster way back to strength, less soreness, better gains.

The data is…less enthusiastic.

A well-cited study comparing cold water immersion to active recovery (like light cycling) found that cold was no better than simply moving your body for muscle recovery markers.

Another recent study showed that cold immersion after resistance training did not enhance strength recovery more than rest, and it may even blunt muscle performance in the short term.

The reason is that inflammation is part of the muscle-building signal. Cooling it down immediately may reduce soreness, but it doesn’t necessarily improve strength gains.

Heat (as explained in this sauna post) was actually shown to support cellular repair pathways without blunting hypertrophy signaling.

In plain English: heat is better than cold for muscle recovery.

A Brief Contrast Therapy Note (Yes, Back to Sauna)

Here’s where the sauna story converges with cold. Sauna expands blood vessels. Cold contracts them.

That rhythmic alternation (hot then cold) appears to train vascular responsiveness. Small studies and practical experience suggest contrast therapy may improve:

• Circulation

• Nervous system balance

• Perceived recovery

But most of the strong long-term mortality data we have comes from sauna alone, not sauna + cold. My nervous system has given a hard NO when it comes to contrast therapy…in the form of dizziness and black dots in my vision. So I choose one longevity stimulus lane at a time.

In Case You Skimmed

• Cold trains your nervous system to tolerate intensity.

• Cold activates the sympathetic nervous system and spikes norepinephrine and dopamine (feel good signals).

• Water at ~50–55°F for a few minutes is sufficient.

• Longer isn’t necessarily better.

• Brown fat burns energy to make heat, but it’s not a weight-loss hack.

• Cold showers count.

• Head dunking is optional.

• Contrast therapy shows promise but isn’t required.

This week, if you’re curious, seek out a cold plunge and take the, well…plunge. Or for the more efficient types, end your morning showers with 30 seconds of very cold water. That should be enough to test the signal.

See if your mood changes, see if you feel overwhelmingly accomplished before breakfast, or maybe a tad hungrier from that extra calorie burn…give it a week, and see how you feel by next Monday.

See you then,
Susan

Longevity in the Wild

This week I was talking to , who, besides being a best-selling author and TV producer, is teaching a journalism course at her alma mater. Call it a vocational hazard, she’s noticed something interesting: many of her students have almost no appetite for confrontation.

Wrong order at a restaurant? They won’t send it back.
Group project imbalance? They’d rather absorb it than address it.

Her theory is it stems from this generation being raised on the internet, where answers are instant, discomfort can be muted, and disagreement can be scrolled past. It made me think about whether we’re removing something our brains evolved to practice: real-time problem-solving. Confrontation requires regulation, language, perspective-taking, and tolerance for discomfort. It activates stress systems and then asks them to settle. In other words: it’s hormesis. Brains, like muscles, respond to use. Resilience isn’t only built in ice baths and saunas. It’s built in awkward conversations and occasionally sending back the fries when you ordered the salad.

It’s Freezing Outside

Like, deep-freeze, cancel-plans, why-do-I-live-here cold. At least in NY it is.

Which feels like the right moment to talk about one of my favorite longevity tools: heat. Specifically, the sauna: what it actually does, why it keeps showing up as a longevity-maker in the research, and how different types compare.

Let’s warm up with a very brief history of the sauna.

A Very Brief History of the Sauna

Saunas aren’t a modern wellness invention. They’ve been around for thousands of years, long before anyone was tracking heart rate variability or selling cold plunges on Instagram.

The earliest saunas are thought to have originated in Finland over 2,000 years ago, where they began as simple pits dug into the earth, heated with stones and fire. They were practical, not luxurious: places to get warm, get clean, and survive long, cold winters.

Over time, the sauna became something more cultural than utilitarian. In Finland, saunas were places for bathing, healing, socializing, even giving birth.

There’s an old Finnish saying that translates roughly to: “Behave in the sauna as you would in church.” In other words: this was a respected, almost sacred space.

What’s striking is that saunas were never about indulgence. They were about regular exposure to heat, followed by cooling and rest…a rhythm that mirrors what we now understand about stress and recovery.

Modern research didn’t invent sauna benefits; it just put language and data around a practice humans were already using intuitively. Which makes sauna one of those rare longevity tools that isn’t new, isn’t trendy, and isn’t extreme…it’s just very old wisdom, finally explained.

Why Heat Works

We didn’t evolve in climate-controlled rooms. We evolved responding to stress (cold, heat, hunger, effort), and we got stronger because of it.

Sauna heat works on a principle called hormesis: a small, controlled stress that triggers beneficial adaptations. Another example is how exercise raises your blood pressure in the moment, but lowers it over time. Your body responds to heat by turning on protective pathways that improve how cells handle future stress.

In plain English: hormesis teaches your body how to cope better next time.

The stars of the heat-induced hormesis is a group of proteins called heat shock proteins.

Here’s How it Works

Heat raises your core body temperature. That activates something called Heat Shock Factor 1 (HSF1), basically the master switch that tells your cells, “Hey, conditions are tough. Time to protect and repair.”

After the GO! signal is activated, other heat shock proteins kick into action. Most notably:

• Hsp70, the heavy lifter. It helps repair damaged proteins and supports your mitochondria (the power plants inside your cells). Healthier mitochondria = better energy, better recovery, and better aging.

• Hsp90, the coordinator. It helps stabilize important proteins and keeps cellular signaling running smoothly, especially when cells are under stress.

• Hsp60, the housekeeper. It plays a role in immune function and protein quality control inside cells.

Together, HSPs fix misfolded proteins (the cellular equivalent of untangling a mess before it causes problems) and train cells to bounce back faster the next time they’re stressed.

In plain English: heat shock proteins are your cells’ janitors, mechanics, and life coaches.

The Finnish Sauna Studies

A lot of modern sauna enthusiasm traces back to the sauna’s geographical origins.

In one landmark study following 2,000 middle-aged men over two decades, researchers found that frequent sauna use was associated with significantly lower all-cause and cardiovascular mortality. And the relationship was dose-dependent.

People who used the sauna:

• once per week saw some benefit

• 2–3 times per week saw more

• 4–7 times per week saw the strongest associations, with roughly:

  • ~40% lower all-cause mortality

  • ~50% lower cardiovascular mortality

    

    Laukkanen T, Kunutsor SK, Khan H, Willeit P, Zaccardi F, Laukkanen JA. Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study. BMC Med. 2018 Nov 29;16(1):219. doi: 10.1186/s12916-018-1198-0. PMID: 30486813; PMCID: PMC6262976.

This wasn’t a “sometimes helps” signal. It was a clear, graded relationship.

That dose-response pattern is one of the reasons sauna keeps showing up in longevity conversations. Very few lifestyle interventions show such a consistent association with outcomes.

And it gets better. The studies also suggest that a 15–30 minute sauna session can increase heat shock protein levels by 50% or more, and those benefits don’t disappear the moment you cool down. They can stick around for days.

Sauna As Cardio

Here’s another reason to love the sauna: it mimics a cardio workout. This makes sense because of what we now know about the blood flow benefits:

• heart rate rises (often into low-moderate exercise ranges)

• blood vessels dilate

• circulation increases

• cardiac output goes up

Sauna places a meaningful load on the cardiovascular system, similar in some ways to brisk walking or light jogging.

It doesn’t replace exercise. But it does act as a cardiovascular stimulus, especially valuable on recovery days, during injury, or when life makes consistent training harder.

Brain Health: Another Surprise!

The same Finnish cohorts later found something else interesting: frequent sauna use was associated with a markedly lower risk of dementia and Alzheimer’s disease.

Using the sauna 4–7 times per week had a substantially reduced risk compared to infrequent users. This doesn’t prove sauna prevents dementia, but it does suggest that repeated heat exposure may support brain health through:

• improved cerebral blood flow

• vascular health

• stress-resilience pathways

When you zoom out, the pattern is consistent: systems that depend on good circulation and stress tolerance tend to benefit from repeated heat exposure.

It will come as no surprise then to learn that regular sauna use has also been shown to reduce symptoms in rheumatic diseases, helping reduce chronic inflammation, progressive joint damage, and impaired mobility.

It’s also been studied as a post-resistance training recovery tool. I can tell you firsthand it works…I am noticeably less sore after hopping in the sauna after a heavy lifting session. I also sleep better, according to my sleep metrics.

Finnish Sauna vs Infrared: Not the Same

Since approximately 0% of my current readership lives in Finland, it’s probably worth clarifying that when I say “sauna,” I’m actually talking about two different options.

They look similar on paper, they feel different in real life, and they stress the body in slightly different ways. But they both work, because what we’re really after is the heat stress.

Traditional Finnish Sauna

This is the classic.

• Hotter temperatures (usually 160–200°F)

• Heats the body from the outside in

• Produces a strong cardiovascular load

• Sessions tend to be shorter and more intense

• Most of the long-term mortality and cardiovascular data comes from this style

Finnish saunas feel…decisive. You go in, you get hot quickly, your heart rate climbs, and you’re very aware that something is happening. From a research standpoint, this matters because these saunas reliably push core temperature and cardiovascular strain…two things that drive the benefits seen in the data.

Infrared Sauna

Infrared saunas play the same game, just differently.

• Lower temperatures (typically 120–150°F)

• Heat penetrates tissue more directly (inside out, loosely speaking)

• Easier to tolerate for many people

• Longer sessions are common

• Fewer long-term outcome studies, but plenty of evidence for physiological benefits

Infrared saunas tend to feel gentler, especially at first. You don’t get hit with heat immediately. Instead, warmth builds gradually, which is why many people can stay in longer. That “inside-out” heating gets compared to a microwave a lot (ok, mostly by me). It’s not a perfect analogy, but close enough to be helpful.

Does One Work Better Than the Other?

Your cells don’t really care whether the box is Scandinavian or infrared…they just respond to the stress. My opinion is that it doesn’t much matter which sauna you choose; it matters that you expose your body to heat stress repeatedly and in a way you can sustain.

In plain English: The best sauna is the one you’ll use.

The benefits come from the pattern, not the perfection. Heat is the tool. Progressive adaptation is the goal.

I use an infrared sauna solely because it is the most accessible to me. I do wish I had access to a Finnish sauna, however, because…and here’s the mildly annoying sign that it’s doing its job…it now takes me about 40 minutes to really start sweating in the infrared.

That’s heat adaptation, my friends. My body has become more efficient at handling heat stress…exactly what the research predicts, just inconvenient enough to know my adaptation is happening.

No Sauna? Hot Baths Also Count.

If you don’t have access to a sauna (or don’t like them), you’re not out of luck.

Hot water immersion (a very hot bath) produces many of the same physiological effects:

• elevated core body temperature

• increased heart rate

• vasodilation (blood vessels opening up)

• activation of heat shock proteins

In fact, some studies have shown that hot baths can improve insulin sensitivity, lower blood pressure, and increase cardiovascular strain similar to moderate exercise...sound familiar?

The key, again, is the rise in core temperature, which is what heat stress does.

A hot bath can simply be water hot enough that it’s uncomfortable but tolerable for 15–30 minutes. On days I’m shorter on time but want the benefits, this is exactly what I do, since 40 minutes to start sweating in the infrared is a bit ridiculous of an ask on a busy day.

Let’s Talk About Sweat

Sweat, in general, is mostly water, sodium, chloride, and smaller amounts of potassium, calcium, and magnesium.

If you sweat regularly, electrolytes are a non-negotiable. Sauna increases blood plasma volume over time (by up to 10%, similar to endurance training), but only if hydration keeps up with demand. Frequent sauna users tend to need more sodium than they think, and those who don’t replace sodium can feel wiped, dizzy, or “off.”

As for toxins, your liver and kidneys are the primary detox organs, and you just can’t rely on sweating to take over for them. However, studies show sweat can contain small amounts of certain harmful substances, including some heavy metals and persistent organic pollutants, suggesting that sweating may serve as an additional elimination pathway.

Wait…Doesn’t Exercise Do This Too?

Yes, you sweat during exercise. And yes, exercise activates heat shock proteins, too. This is one of the reasons exercise works so well over time.

In fact, as far as sweat goes, a study found that the removal of heavy metals from the body through dynamic exercise may be more effective than removal through static exposure to a hot environment.

But exercise also creates damage…microscopic muscle breakdown, connective tissue strain, and nervous system fatigue. That damage is necessary, but it comes with a recovery cost.

Sauna actually complements exercise quite nicely. Sauna use after training has been associated with:

• improved muscle blood flow

• enhanced nutrient and oxygen delivery

• faster clearance of metabolic byproducts

• increased expression of heat shock proteins involved in muscle repair

In plain English: sauna helps muscles repair what exercise just challenged.

So while exercise and sauna both activate similar stress-response pathways, they do it from different angles. Used together, they allow you to train hard, recover better, and continue adaptation on recovery days or days when training just isn’t possible.

Let’s Talk Timing

Because sauna use directly impacts physiology, it makes sense to time it well.

• Sauna earlier in the day → often boosts alertness

• Sauna late afternoon/early evening → improves sleep onset

• Very late sauna (right before bed) can backfire for some people by raising core temperature too close to sleep

You might be wondering about contrast therapy, the practice of alternating heat with cold.

There is evidence that pairing sauna with cold exposure can amplify certain adaptations, particularly around circulation and nervous system resilience.

Personally, I don’t practice contrast therapy regularly. Cold exposure after a heat makes me dizzy, which is my cue that it’s not a great fit for my nervous system. My husband can contrast all day long and feel even better combining them than choosing either the sauna or the cold plunge.

That’s an important point: longevity tools only work if your body tolerates them well.

I’ll go deeper into cold therapy in a future post, including when it makes sense, when it doesn’t, and how to think about cold exposure without forcing yourself into misery.

In Case You Skimmed

• Sauna is a powerful longevity tool because it exposes the body to controlled heat stress, which triggers protective adaptations.

• Heat activates heat shock proteins, which support cellular repair, mitochondrial health, and stress resilience.

• Regular sauna use is associated with lower cardiovascular and all-cause mortality, with stronger benefits at higher weekly frequency.

• Sauna acts like a form of passive cardio, increasing heart rate, circulation, and cardiac output.

• Frequent heat exposure has been linked to better brain health, including lower dementia risk in long-term studies.

• You don’t need a traditional Finnish sauna to get benefits, infrared saunas and hot baths also count.

• Sauna supports recovery from exercise by improving blood flow and reinforcing repair pathways.

• Sweating requires electrolyte replacement, especially sodium.

Adaptation happens when the body practices responding to stress. This week, step into the heat. Any type of sauna if you can, a hot bath if you can’t. Let the body do its work, then see how you feel by next Monday.

See you then,
Susan

Longevity in the Wild

This week, a new friend shared that she’s giving up caffeine as part of getting healthier. That’s a meaningful move; especially since most of her caffeine was coming from diet soda. Retiring diet soda is always a good idea. What confused me, though, was her assumption that caffeine itself was the problem holding her back from “being healthy.” Coincidentally (and helpfully), a large new study published just last week in JAMA followed more than 130,000 adults over several decades and found that caffeinated coffee and tea (but not decaffeinated) were associated with a lower risk of dementia and less cognitive decline, with the strongest benefits showing up at moderate intake (about 2–3 cups of coffee or 1–2 cups of tea per day). In other words: caffeine, in the right context, seems to be doing us just fine. The delivery system matters. Coffee and tea behave very differently in the body than highly processed diet soda, and mixing those up is where the wellness whiplash makes me glad I have a Substack to explain things.

“Did you have your creatine today, Susan?” an woman I run into around town asked me casually.

Before I could answer, she continued, “I put one scoop in my coffee this morning, and I’ve got the other right here in my water bottle.”

I’m smiling as I write this, because she’s older than I am…not exactly who I’d expect to be starting a conversation about creatine. So how on earth did a supplement once reserved for gym bros and bodybuilding forums become a normal addition to her coffee and water?

Yet, here we are.

For decades, creatine research lived almost entirely in the world of sports performance: short bursts of power, repeat sprint ability, maximal strength. That is its “gym bro” origin story.

What’s changed in recent years is the scope of the questions researchers are asking.

Instead of stopping at “Does this help people lift more?” (we already know it does), they started asking a more interesting question: What happens when cells are under high energy demand anywhere in the body?

And like so many other molecules, once you shift the framing, a bigger picture comes into focus.

Viewed through the lens of a compound that supports cellular energy wherever demand is high, creatine suddenly makes a lot more sense. What researchers are exploring now is its role in brain energetics, mental fatigue, sleep stress, skin rejuvenation, and (YEAH!) aging.

We are currently living in a moment where creatine has transcended squats to support all the systems that work hard every day. What a world.

Let’s break down what that actually means and how it can make a difference in your world.

What Does Creatine Do?

At a cellular level, creatine’s role is very specific.

Some science first: cells use ATP (adenosine triphosphate) as their immediate energy source. When ATP is used, it becomes ADP. Creatine, stored as phosphocreatine, donates a phosphate group to regenerate ATP rapidly.

In plain English: Creatine helps your cells recharge faster when energy demand spikes.

This phosphocreatine system is especially important in tissues with high, fluctuating energy demands and limited tolerance for energy failure. Muscle surely jumps to mind, but as we are all now learning…the brain also fits snugly within these requirements.

Beyond the Powder, Where Creatine Comes From Naturally?

Your body gets creatine in two ways: from food and by making it itself.

Dietary creatine is found almost exclusively in animal protein, primarily red meat and fish. If you eat those regularly, you’re getting some creatine. If you don’t, you’re getting very little.

Even if you do eat meat, the amounts add up slowly. To get a typical 3–5 grams of creatine from food alone, you’d need to eat pounds of meat every day. Most people don’t. (Cross-referencing to my protein post here)

Our bodies also make creatine, mainly in the liver and kidneys, from amino acids. But there’s a caveat with that: the process to make it is metabolically expensive. It requires energy and something called methyl groups.

Sidebar: A note on methylation (and MTHFR variants)

Methyl groups are like tiny chemical “tokens” your body uses for all sorts of essential jobs: detoxification, neurotransmitter production, hormone metabolism, DNA repair…the list is long.

People with certain MTHFR genetic variants don’t recycle these methyl groups as efficiently as their non-variant friends do. That means their methylation system is already working a little harder to keep up.

When you make creatine internally, you spend a decent amount of methyl groups to do it. For some, especially those with MTHFR variants, supplementing creatine can free up methyl groups to go do other important work. That doesn’t mean everyone with an MTHFR variant needs creatine. But it does explain why some people feel noticeably better when they supplement.

Muscle: The OG Use Case

Creatine is one of the most consistently effective ergogenic aids ever studied (that is fancy talk for a performance enhancer). But don’t worry, it’s classified as a supplement, it’s WADA-approved, and even officially encouraged by the International Society of Sports Nutrition.

Meta-analyses and research galore show creatine supplementation:

• increases maximal strength

• increases lean body mass

• improves performance in repeated high-intensity efforts

• enhances adaptations to resistance training

These effects are seen across all age groups; but even more profoundly in older populations, creatine combined with resistance training has shown increases in muscle mass, improvements in strength, and better functional outcomes.

This matters because muscle is metabolic, protective, and directly tied to fall risk and independence. I won’t spend too much time here, since any something search can knock you over the head with why creatine is good for muscles.

The Brain: Where Creatine Gets Smart

Here’s where creatine stopped being optional for me.

The brain consumes ~20% of resting energy expenditure while representing ~2% of body mass. And neurons are extremely sensitive to energy availability. I think we can all attest to that.

Creatine supplementation has been shown to increase brain phosphocreatine content by 5–15%, which may support brain bioenergetics and cognition, particularly in older adults.

Research now shows creatine supplementation can improve:

• working memory

• reasoning and processing speed

• mental performance under stress

But wait, there’s more! Its effects are most pronounced when the brain is energy-challenged…like during sleep deprivation, hypoxia (low oxygen, like high-altitude), metabolic stress, or (sigh) aging.

Creatine for Sleep Deprivation + Brain Fog

One of the more compelling areas of research looks at creatine’s ability to blunt the cognitive effects of poor sleep or sleep loss.

A randomized trial found that creatine can:

• partially restore cognitive performance after sleep deprivation

• improve reaction time and reasoning

• blunt the metabolic cost of prolonged wakefulness

In plain English: Creatine can help the brain cope better when sleep is compromised.

For me, this was one of those I’ll believe it when I see it papers. And on a recent overnight flight across multiple time zones, I had occasion to self-experiment. I dumped 20g of creatine in my coffee upon landing, and…BINGO. I was fine. Seriously.

Obviously this isn’t a “sleep replacement.” Nothing replaces sleep, but it does support brain energy when your neurons are stressed. For anyone navigating parenting, caregiving, perimenopause, or life in general, I highly recommend giving it a try.

Creatine and Skin: The Plot Twist Even I Didn’t See Coming

This was not on my original creatine bingo card.

When I first started digging into the research, I expected muscle and brain. What I didn’t expect was skin. But once I understood how creatine works, it actually made a lot of sense.

Skin is an energy-hungry tissue. The cells responsible for maintaining firmness, elasticity, and repair (particularly fibroblasts in the dermis) rely on ATP just like muscle and brain cells do. When energy availability drops, so does their ability to keep up with collagen production and repair.

Creatine plays a role because…all together now: it supports cellular energy.

Research suggests that creatine, particularly when applied topically, can:

• increase cellular energy in skin cells

• stimulate collagen synthesis

• improve skin firmness and elasticity

• reduce visible signs of aging like sagging and fine lines

In plain English: Creatine can keep our skin tight.

The interesting part is that this is not plumping temporarily (oh, we’ll get to that, keep reading). It’s supporting the machinery that allows skin cells to do their job.

Women, Aging, and Creatine

Emerging research suggests women, particularly in peri/menopause, might benefit a whole lot from creatine because hormonal changes influence muscle and metabolic energy. Also, creatine stores tend to be lower to start with in women…a double whammy.

In plain English: Creatine comes along for the cellular haywire ride as the responsible chaperone, keeping the muscles firing and brain fog at bay.

How Much to Take

Let’s get into the how-to portion.

For muscle support, most studies use 3–5 grams per day. That’s the classic, well-established, well-studied dose.

For brain and cognitive effects, research often uses higher doses, 10 grams or more per day to meaningfully increase brain creatine stores. Muscles are very greedy, so the higher dose is to overcompensate so there are leftover stores for the brain. Optimal brain dosing isn’t fully nailed down yet, but emerging data supports higher intakes.

Personally, I took 5 grams daily for years. After digging into the brain-health research, I bumped myself up to 10 grams per day, which I take in my morning coffee. That change lined up with improvements in mental clarity on high-demand days. And, as mentioned earlier, I now know 20 grams kills my jet lag quite nicely.

However, dosing is individual, and more isn’t automatically better.

Water Retention

Yes, creatine can cause bloating for some people…especially at the beginning. (This is the aforementioned plumping reference, for those who have been paying attention and made it this far. Hi, !)

Here’s what’s actually happening: creatine pulls water into muscle cells. That is, in fact, part of how it works so well.

I want to be clear: this is temporary intracellular hydration, not weight gain, not "getting fatter.”

For some people, that increase in fluid can feel…well, horrible. Like bust out the fat jeans horrible (ahem, my sister, who yelled at me from across the country).

Some ways to address this are:

• starting with a smaller dose

• staying well-hydrated (yes, more water)

• and letting your body adjust over 1–2 weeks

Most people find themselves back in their skinny jeans as muscle creatine levels become saturated.

Some give up entirely (my sister), but keeping with her example…her baseline stores were probably much lower than mine; vegetarians (like her) tend to have 20-30% lower muscle creatine stores. So when she finally gave her body the goods, it sucked it up like there was no tomorrow. A bigger deficit leads to faster loading, which means more noticeable intracellular water retention. It’s just science. And it doesn’t last forever. (Maybe she should give it another go?)

Why Creatine Gummies Are Mostly a Marketing Trick

Some might think the gummy version will circumvent the bloat. And yes, creatine gummies do exist, but they’re not ideal if you want, well, actual creatine doses.

To hit the typical 3–5 g creatine dose, you’d need a lot of gummies, which means extra sugar, fillers, and calories. The efficacy claims typically trail behind what you can get from straight creatine monohydrate powder, which is the form most studied and recommended by experts.

My choice is to stick with the classic powdered form; it’s cheaper, pure, and proven. There are other forms of creatine out there, and the one I recommend to my friends who feel the bloat is this one (that is typically sold out, sorry) from LVLUP, a brand that looks more intimidating than it is.

Creatinine (Yes, there’s an extra “in” in there)

For some reason, there is a myth around creatine that has followed it like a dark shadow for decades, and it’s rooted in a misinterpretation of lab values.

Myth: Creatine is hard on your kidneys.

Here’s why this myth persists: creatine is broken down into creatinine (note the extra “in”), which is a waste product filtered by the kidneys. Because of this, creatine supplementation can raise blood serum creatinine levels .

Where this gets…sticky… is that the bloodmarker creatinine is used as a proxy for kidney function, but it’s actually influenced by a number of inputs, including muscle mass, protein intake, hydration status, and yes, creatine supplementation

Truth: In people with normal kidney function, decades of research show that creatine supplementation does not cause kidney damage.

If Your Labs Come Back and Your Doctor Raises an Eyebrow

If a lab flags creatinine and you’re otherwise healthy, a reasonable next step is simply to say:

“I supplement with creatine. I understand that can raise creatinine levels. Can we look at my eGFR and overall kidney function in context?”

That one sentence changes the conversation from alarm to interpretation.

For what it’s worth, this is exactly the conversation I had, except in my case, it ended with my doctor suggesting I increase my dose once we reviewed the bigger picture. So yes…another wonderful plot twist.

Who Should Be Thoughtful About Creatine

Having touted its safety profile and debunking the dark myth, I must take a step to the side and note that there are people who should be cautious or consult a clinician first:

• anyone with existing kidney disease

• significant renal impairment

• or complex medical conditions involving kidney function

That’s not because creatine is inherently dangerous; it’s because interpretation of labs and dosing should be individualized and watched. There is just no need for wild card variables when it comes to kidney markers.

For everyone else, creatine has one of the best safety profiles of any supplement.

In Case You Skimmed…

• Creatine isn’t just for bodybuilders; it’s gaining recognition for brain support under stress and aging.

• It helps regenerate cellular energy (ATP) in muscle, brain, and even skin.

• Creatine can partially buffer cognitive decline after poor sleep.

• Bloating can happen but is usually mild and transient.

• The powdered form of creatine monohydrate is effective, tried, true, and tested.

• Typical muscle doses are 3–5 g; brain benefits are showing around 10+ g.

If you’re already taking creatine, great! You might consider whether a higher dose makes sense. If you’ve been curious, give it a whirl; it’s a pretty low-drama place to start with supplements. And if you tried it once and backed off, it may be worth another look after learning a bit more.

Just give it time. Creatine works best once your muscle stores are saturated, which can take a week or two. Water retention early on can happen; remember that’s part of how it works, not a reason to quit.

For me, creatine is a daily staple. Simple, well-studied, and supportive of the systems I (and most people) lean on most.

So maybe don’t judge it by next Monday. Give it a couple Mondays…and then tell me what you notice.

See you then,
Susan

Longevity in the Wild

This week, I was reminded of the power of preparation. In my weight-training gym, we welcomed back a woman who’d had a knee replacement just a month ago. A MONTH. When I told her how impressive it was that she was already back, she credited her smooth recovery to the six months prior to surgery she’d spent preparing her body, mostly in the very weight room in which we were standing. She summed it up perfectly: “If you’re thinking about knee surgery, don’t even consider it unless you’re able to fully prepare going into it.” It stuck with me. Because that logic applies to far more than surgery. The work you do before you need it is what carries you through when you do.

The ice and snow lately have made my walks a little more…tenuous. I’ve definitely had a moment or two where I caught myself mid-slip and thought, okay, that could’ve gone differently. However, the risk of falling isn’t front-of-mind enough to slow my pace dramatically…and I’d very much like to keep it that way.

Because here’s what’s in the back of my mind: falls are an inflection point. They can be the moment when “feeling fine” turns into months or years of recovery, or worse, they can begin a doomsday cascade. Bone health is a huge part of what determines whether a slip is a scare or something worse.

For me, this isn’t abstract. I’m smack in the middle of perimenopause, with less-than-stellar genetics, a rough family history, and a recent bone density scan that landed me uncomfortably close to the osteopenia line. So yes, it’s personal. But it’s also universal. Because bone loss doesn’t announce itself with pain, and by the time it shows up on a scan, it’s already been happening behind the scenes for years.

Which is why bone health deserves our attention long before anyone tells us to worry about it.

Define “Bone”

Bone isn’t a single thing. It’s a composite tissue, more like reinforced concrete than a solid block. Hard, but nuanced.

Roughly speaking, bone is made up of:

• A mineral component (mostly calcium and phosphorus) that gives bone its hardness and resistance to compression. Think of this as the building’s concrete.

• An organic matrix (largely collagen) that gives bone flexibility and tensile strength, the ability to bend slightly without snapping. Think of this as the building’s rebar.

• Living cells, which you can think of as the building’s engineering and maintenance crew:

  • Osteoblasts, which build new bone

  • Osteoclasts, which break down old or damaged bone

  • Osteocytes, mature bone cells that act like sensors, communicating mechanical stress and signaling where reinforcement is needed

This combination is what makes bone both strong and tricky. Too much mineral without enough collagen, and bone becomes brittle. Too much collagen without mineral, and bone becomes soft.

So, what determines how much “concrete” and how much “rebar” your bones lay down over time?

Force.

Force

Bone is constantly remodeling. The signals you are sending right now influence whether osteoblasts stay active or gradually step back, and this remains true throughout life.

And here’s something I found interesting: bone responds to how you use your body more than how often you move it.

Gravity Is the Boss

Your bones are constantly asking one question:

How much force do I need to withstand?

Gravity + impact + load = the answer to that question.

When we walk, lift, jump, land, or carry something heavy, gravity pulls down, and our skeleton has to resist it. That resistance is what tells osteoblasts:

“Hey, we need reinforcement here!”

When that signal is loud enough and repeated enough, bone density increases or is preserved. That is why, yes, heavier people tend to have better bone density, which may be the only positive side to obesity. Still, the negatives outweigh (pun intended) this one benefit, in my opinion.

When the signal gets more quiet (or is even absent) osteoblasts stand down, and bone slowly thins. (Genetics do play a role in this, too, so hang onto your questions until we get to that part.)

Some examples of quiet or absent osteoblast signaling are:

• Astronauts in space

• People on prolonged bed rest or those with a sedentary lifestyle

• Non– or low-weight-bearing athletes

Movement alone isn’t the signal. Load against gravity is.

Why Gymnasts and Swimmers Don’t Look the Same on a Scan

This is one of the clearest examples of how bone actually works.

Gymnasts routinely show higher bone density than the general population. They jump, land, absorb force, and load their skeletons in varied, unpredictable ways. Bones hear that signal and respond by getting stronger.

Swimmers, on the other hand, are incredibly fit, but water removes most of the gravitational load. The skeleton isn’t asked to resist the same amount of force, so bone density doesn’t increase in the same way.

Same athleticism. Very different skeletal signals.

And before anyone throws chlorine at me…yes, swimming is absolutely better than not exercising at all. There is mechanical tension. It’s just not the same signal as repeated impact and load.

Running is another interesting case. Lifelong runners (myself included) tend to become extremely efficient at it. And depending on distance and intensity, that efficiency can actually work against bone density. In many cases, it’s simply not enough stimulus to move the needle meaningfully…I know this firsthand.

The takeaway is simple: your bones don’t care as much about how hard you’re working as how much force they’re asked to manage.

Can You Feel Bone Loss Happening?

This is the tricky part, and probably the most frustrating one.

No, you can’t feel your bones thinning.

Bone loss is silent. There’s no ache, no warning twinge, no early pain signal. Osteopenia and osteoporosis develop oh-so-quietly, often over years, without symptoms.

That’s why so many people are shocked by a scan result. They feel strong. They feel active. They feel fine. Ask me how I know.

The first “symptom” is often a fracture, and that’s not a great way to find out.

Which is why bone health is a proactive conversation, not a reactive one.

What is a Bone Density?

Before we talk about supplements or anything more advanced, it helps to know what we’re even tracking.

A bone density scan (often called a DXA scan) is a low-radiation imaging test that measures how dense your bones are. Sites most commonly measured are at the hip, spine, and sometimes the forearm. These are areas where fractures tend to be the most consequential.

The results are usually reported as:

• a T-score, which compares your bone density to that of a healthy young adult

• and sometimes a Z-score, which compares you to people your own age

In very simple terms, the scan is asking:

How much mineral is packed into your bone structure, and how does that compare to what we’d expect?

It doesn’t measure bone “strength” directly, but bone density is a strong predictor of fracture risk, especially when combined with age, muscle strength, and fall risk.

This is how people often learn they’re:

• normal

• osteopenic (lower than ideal bone density)

• or osteoporotic

Let’s Talk About Genetics (Without Throwing Our Hands Up)

Genetics play a big role in bone health; there’s no getting around that. Research suggests that 60–80% of your peak bone density is inherited, which helps explain why some people seem to coast through life with sturdy bones while others hit red flags earlier.

This is also why family history matters. Some clues as to your genetics are if you have relatives who’ve had hip fractures, wrist fractures, spinal compression fractures, early osteoporosis diagnoses…that sort of thing.

But genetics don’t have to dictate your entire outcome. Genetics determine how high your bone-density ceiling might be, but how you live and what you ask your bones to do determines how fast you move toward the floor.

Two people can have the same genetic risk and end up in very different places depending on how much load, hormone support, nutrition, and muscle stimulus their bones experience over time. For those starting behind (ahem, hi again), it just requires more work and attention.

The Upside of Knowing Your Risk

Genetic risk is useful. Knowing you’re predisposed to lower bone density means you can jump (see what I did there?) on the prevention train at an earlier stop.

You can:

• do weight and heavy resistance training

• pay attention to hormonal transitions and intervene as soon as possible

• support bone with adequate protein and micronutrients

• track changes before they become problems

Bone responds best when you act before it’s fragile; like muscle, it’s best to have more in reserve going into your future years.

Hormones: Why Women Feel This Sooner

Hormones are one of the strongest regulators of bone remodeling.

Estrogen, in particular, helps:

• slow bone breakdown

• keep osteoclast activity in check

• support balance between formation and resorption

When estrogen drops (as it does in perimenopause and menopause), bone breakdown accelerates. This is why women tend to see faster declines in bone density earlier than men. And that’s also why someone can be active, thin, and “healthy” on paper and still end up borderline osteopenic in their 40s. (Hi.)

Men don’t get a free pass, though…testosterone supports bone, too, but the decline is usually slower and later.

This is why waiting until “later” is risky, especially for women. The window where prevention is easiest is often before anyone tells you there’s a problem.

Peak bone mass is typically reached in early adulthood. After that, the goal shifts from building to preserving. I wish young women were blatantly told this. If your genetic ceiling was lower to begin with, there’s less margin for loss, and the decline can happen sooner.

Why Muscle Is the Bone’s Best Friend

Here’s where we loop back to muscle and why these two systems are inseparable.

Muscle doesn’t just move bone. It pulls on bone.

That pulling force creates mechanical strain: one of the loudest signals for osteoblasts to respond. When muscle gets stronger, the pull on bone increases, and bone adapts by reinforcing itself.

This is why:

• Stronger muscles = stronger bones

• Resistance training outperforms walking for bone density

• Muscle loss accelerates bone loss

Bone responds to gravity plus muscle-generated force. So when we lift heavy, we’re giving bone a reason to stay dense.

Fall Risk: Where This All Becomes Very Real

Low bone density on its own is concerning. Low bone density plus low muscle strength is dangerous.

Falls are one of the leading causes of injury in older adults, and fractures are what turn a fall into a life-altering event.

Muscle reduces fall risk by:

• improving balance

• increasing reaction speed

• absorbing force

Bone reduces fracture risk by:

• resisting compression

• preventing cracks from propagating

You want both. Strong muscles help you not fall. Strong bones help you not break.

What You Can Control

You can’t change your genetics, you can’t stop the passage of time. Here’s the part I really want people to hear:

It is possible to slow bone loss. It is often possible to improve bone density. And it is almost always possible to reverse the trajectory, even if you don’t end up back at peak levels.

You can control:

• how much load your bones experience

• how strong your muscles get

• how early you start paying attention

• how consistently you send the signal

Bone health can be built and reinforced. Bone is living tissue; it responds when you change the inputs.

Supplements for Bone Health

Nutrients are part of the equation here; especially when you’re trying to support remodeling while training.

Here are the ones that move the needle and that I take religiously:

Calcium

Calcium is a primary mineral component of bone. If intake is too low, the body will pull calcium from bone to keep blood levels stable…not ideal.

Vitamin D

Vitamin D helps your body absorb calcium. Low vitamin D levels are consistently associated with poorer bone density and higher fracture risk.

Vitamin K2

Vitamin K2 helps direct calcium into bone and teeth, rather than letting it accumulate in soft tissue. You can find vitamin D often paired with K2.

Magnesium

A large portion of the body’s magnesium is stored in bone, and magnesium plays a role in both bone structure and vitamin D metabolism.

Protein

Bone has a protein matrix; under-eating protein undermines bone remodeling. Nutrition and resistance training go hand in hand for bone health.

Where Peptides Fit

There’s a peptide for almost everything these days! I LOVE PEPTIDES. And there are some out there for bone health show promise in specific contexts, especially when bone loss is significant or rapid. I’m aware of them. I’ve researched them. And yes, I’m considering them. (I don’t mean collagen peptides that go in my coffee, I’m talking the lab-made ones.) Parathyroid hormone peptides currently have the strongest clinical evidence for improving bone density.

But here’s my current stance:

I’m saving bone-support peptides for a scenario where weight training, nutrition, and nutrient supplementation aren’t moving the needle enough.

There are also very effective medications for osteoporosis, and for some people they are absolutely the right tool; especially after fractures or with rapid bone loss. Thrilled these are out there and available, should I need them one day.

For me, and I hope for most, the current plan is:

1. Lift heavy to build muscle

2. Support bone with nutrition and supplements

3. Monitor hormones

4. Track progress over time

5. Revisit advanced tools only if/when needed

In Case You Skimmed

If you’re wondering where to begin, here’s the short list:

1. Load your skeleton and build muscle.
Bones respond to force. Resistance training and impact (appropriately scaled to you) give osteoblasts a reason to build. Muscle pulls on bone. Stronger muscles create stronger signals. This is why muscle and bone health are inseparable.

3. Eat enough protein.
Bone isn’t just mineral; it has a protein matrix. Under-eating protein makes bone remodeling both more difficult intrinsically and undermines muscle growth.

4. Support bone nutritionally.
Calcium, vitamin D, magnesium, and vitamin K2 all work synergistically to support bone structure. They’re the building materials.

5. Start earlier than you think you need to start.
Bone responds best when you intervene before fragility sets in. Earlier action = more room to maneuver.

6. Your genetics do impact your lifelong ceiling.
This is the bad news. The good news is that you have control over the message your bones receive every day, and that can make an impact.

Stronger today, harder to break later…that’s the name of the game.

And no, this isn’t a “see how you feel by next Monday” situation (though I do love a consistent ending). This one’s more about the long game: put the support in place, and see how you’re doing in 50+ Mondays.

See you then, if not before,
Susan

Longevity in the Wild

This weekend, I heard something so simple, I can’t stop smiling (and even translated it into a general note yesterday). My son and I were headed to a sixth-floor destination. The elevator doors were open. Zero obstacles. And my son looked at me and said, “Mommy, let’s take the stairs.” TAKE THE STAIRS…OF COURSE! So, the lesson here is simple: if you’re able to, take the stairs. Longevity hides in unremarkable daily decisions.

Last week we zeroed in on protein and why the amino acid leucine matters. Brief recap: it’s the signal that tells your muscle “hey, we’ve got a green light to build and repair.”

This week is about another signal your body uses to stand at muscle-building attention: weight training.

I know. I sound like a broken record. Muscle this, muscle that, organ of longevity, blah blah blah. But here’s the thing: it keeps being true. Annoyingly, relentlessly true.

So, let’s get this party started.

Weight training tells your body:

• keep this muscle

• build more of it

• strengthen the bones underneath it

• handle sugar better

• stay metabolically expensive (in a good way)

Without that signal, your body might start to downsize (in a bad way). With it, you might just appear to age backwards.

Why Weight Training Works and Why “Just Moving” Doesn’t

Let’s clear up a big misunderstanding.

Moving your body is great. Walking is great. Pilates is great. High-intensity cardio is great. Flailing your arms around enthusiastically is…fine.

But none of those send a strong enough signal to build or preserve muscle.

Here’s why:

Muscle responds to mechanical tension: real resistance that creates microscopic stress in the muscle fibers. When you lift a weight that feels genuinely challenging, your body detects: This is demanding. I’d better adapt.

That adaptation is called muscle growth and maintenance. And with mechanical tension comes progressive load, meaning you have to keep upping the ante.

Light movement doesn’t create enough tension. Endless reps don’t create enough stimulus. Sweat doesn’t equal signal. Yes, I know the literature is coming around on high reps, low weight, but I think most people underestimate the number of reps they would need. These days I am all about efficiency, and heavy weights (for me) work circles around…well, arm circles.

Muscle Is Doing Way More Than You Think

Ok, why the focus on muscle. Let’s review.

Yes, muscle helps you look better. Yes, it helps you feel stronger. But it’s also doing a lot behind the scenes:

• Bone protection: muscle pulls on bone, which tells bone to stay dense (this is how you defend against osteoporosis)

• Blood sugar control: muscle is a massive glucose sink; the more muscle you have, the more sugar you can clear from your bloodstream

• Metabolic flexibility: muscle gives you more wiggle room; people with more muscle can often “get away with” a bit more dietary flexibility because their body knows where to put it

• Illness and injury recovery: muscle is reserve capacity; you bounce back faster when things go wrong

• Aging insurance: it’s harder for sarcopenia and frailty to hit those who keep muscle on their bones

Some Gravitas to Add More Weight to the Conversation

Did you know that the over the age of 60, the risk of death within one year after a fall with a fracture is up to 25%? And those who are non-sarcopenic, with higher bone density fare much better and have fewer fractures.

Now this conversation is personal; I’m working against some bad genetics in the bone department. And I’m not starting from zero. I’ve exercised my entire life: competitively, for fun, and even to the point of beating my very athletic husband in a half Ironman in 104-degree heat. And still, a recent bone density scan confirmed what my genetics had been hinting at all along. That was the moment I stopped relying on “being active” and got serious about heavy weight training, not just for muscle, but for bone health too (that will be another post one Monday). Life has a way of clarifying priorities.

I now affectionately refer to those 20-somethings who look like bookmarks as FFAs (Future Fall Risks). No, not everyone has gotten the memo about meat on your bones being a good thing, so we’ll give them some grace…because it’s never too late to start! Even into your 70s, 80s, or beyond. Older adults who begin resistance training later in life still gain muscle strength and size, which help protect independence and reduce fall risk. This is has been studied, documented, confirmed. I’ll repeat: IT IS NEVER TOO LATE TO START!

Please click on those links if you want to be wow-ed by the research!

Why Resting Is Part of the Equation

Here’s a welcomed plot twist: muscle doesn’t build when you lift the weight. It builds after, when you rest.

The weight is the signal. Rest is the construction phase.

When you lift something heavy, you create tiny disruptions in the muscle fibers. During rest (especially when you’ve fueled with enough protein), your body repairs and reinforces those fibers so they’re better prepared next time.

Even resting between sets within your strength training workout is important and makes your workout more effective. You need anywhere between 2-5 minutes to fully replenish your ATP (energy). Pro tip: creatine ingestion prior can cut that down to 2-3 minutes. I take it, I notice a difference.

If you don’t rest, there’s no adaptation, just breakdown.

Here’s the part where everything clicks.

Protein gives your body the raw material. Leucine (from protein) flips the biochemical switch. Weight training provides the mechanical signal. Rest is when your body builds and adapts.

Miss any one of those steps, and the system underperforms.

This is why just eating more protein doesn’t magically change your body.
It’s also why flailing around doesn’t either. And it’s why pushing harder without resting eventually backfires.

Your body is very logical.

Give it the materials and the signal…then get out of the way and let it do what it’s designed to do.

So…How Do You Actually Lift?

Before anyone panics: this is not a programming post. You don’t need a spreadsheet; you just need to understand what counts.

Let’s put some structure around this, because “just lift heavy” is not helpful.

First, two quick definitions (so we’re speaking the same language):

• A rep (short for repetition) is one complete movement.
  Example: one squat = one rep.

• A set is a group of reps done back-to-back before resting.
  Example: 8 squats in a row = 1 set of 8 reps.

How Often Do You Need to Lift?

For longevity, 2–3 strength-training sessions per week is the sweet spot for most people.

• 2 days/week → you’re doing great

• 3 days/week → even better

• More than that → only helpful if your recovery is on point

Define “Heavy”

“Heavy” means a weight you can lift for 6–10 reps, where the last few reps feel genuinely challenging.

• If you could easily do 15 more reps → too light

• If you fail at rep 3 → too heavy

• If you finish knowing you maybe had 1–2 reps left → perfect

That’s the signal.

How Many Sets?

For each exercise, 2–4 sets is plenty. You don’t need more to get the benefit if the weight is appropriate. Quality beats quantity here.

What Kind of Exercises Matter Most

You don’t need dozens of movements, just big, compound exercises that use multiple muscle groups:

• squats or leg presses

• deadlifts or hip hinges

• presses (chest or shoulders)

• pulls (rows or lat pulldowns)

These give you the most bang for your buck and send the strongest signal.

If working out from home is your thing, I can personally recommend Lifted by Holly Rilinger (an actual icon), which has livestreaming classes. I also like Peloton’s weight classes and am giving Ladder a whirl while we’re snowed in at the moment…but for any of these, you’ll need access to heavy weights for the progression part to work long-term.

Remember that Rest Is Part of the Plan

Rest between sets. 60–120 seconds is good.

Rest between workouts. Give the same muscle group at least 48 hours before training it again.

This is not being lazy, this is when muscle rebuilds.

Lift → rest → adapt.

A Reassurance

You cannot accidentally get bulky doing this. You can accidentally get stronger, more stable, and harder to knock down. And that’s kind of the point.

Two Quick Notes

Burn vs. Build

A note on my past. If you’ve known me long enough, you’ll remember my obsession with barre and megaformer classes. I still love both. They create sustained muscular tension, build control, and absolutely torch endurance.

What I didn’t appreciate until recently is that they don’t do the progressive load portion like weight training does…it’s simply more efficient to throw plates onto the weight bar and get stronger week to week. So now I think of them as excellent complements: I like them for muscular endurance, while weight training remains my foundation.

Cardio

Before anyone asks or throws BDNF in my face…yes, high-intensity and steady-state cardio absolutely has a place in the longevity world. I LOVE CARDIO. It’s powerful for cardiovascular fitness, mitochondrial health, and metabolic flexibility. It’s just not a substitute for weight training. We’ll dig into it another Monday, along with what BDNF is, because who doesn’t love a longevity acronym.

One Strong Recommendation (If You Can Swing It)

If it’s an option, I’m a big fan of working with a good trainer, even briefly…just long enough to learn what challenging for you actually feels like.

I didn’t fully comprehend this until fairly recently.

Let me give credit where it’s due: I accidentally crashed my friend’s training session one day and promptly discovered…everything I now won’t stop talking about. (Thank you, Steph!)

Having someone help me choose the right weight, safely push close to failure, and know exactly when to stop made all the difference. It’s surprisingly hard to find that edge on your own, mostly because it’s scary. Knowing someone’s there to grab the bar if things go sideways is oddly liberating, and it accelerated my progress faster than I expected.

On a good week, I train with a small group and a trainer three times. Other weeks it’s two. Some weeks, it’s less than that. And yet, I’m stronger, I feel better, and I look better doing less than I ever did doing more.

Magic.

One Last Thing (Because You Might Will Be Sore)

When you start heavy lifting, there’s a very good chance you’ll be sore. That’s normal. It doesn’t mean you did anything wrong; it means your body got a new signal, and it’s reacting.

Simple things can help. Drinking lots of water with electrolytes, for example. Magnesium, in particular, goes a long way in taking the edge off soreness and supporting sleep, which helps in and of itself.

There are also more advanced recovery tools. I love BPC-157 (a peptide), and there are a few other peptides that people love. We’ll get into recovery properly another time.

In Case You Skimmed

• Protein gives your body the materials, leucine flips the switch.

• Weight training is the other signal that tells your body to build and repair.

• “Heavy” means challenging for you.

• Progressively adding heavier weights keeps the process going.

• Rest is when the building actually happens.

• It’s never too late to start.

Try it out this week. Lift in a way your body notices, fuel it properly, then see how you feel by next Monday.

See you then,
Susan

Longevity in the Wild

This week, I got wild. After months of circling organ meats (and even longer having them in the house), I finally took the plunge, after that same coffee with Kelly I mentioned last week…we really covered a lot of ground (beef, ha!) in that convo. What finally did it was accepting that beef organs contain many of the same minerals, vitamins, and enzymes I already supplement…all in one place, and in a far more bioavailable form. Also, my sister jumped in first (capsules, after her own research), which helped. I went with a powder called Organised. It smells worse than it tastes, and blended into a protein shake, it’s…fine. Just maybe don’t read the ingredients list.

Because the reality is, for those of us who’ve spent any time in the longevity or health world, protein has been the foundation for a long time. Which is why the recent update to dietary guidelines that gave protein a big promotion feels less like a revelation and more like the mainstream finally catching up.

The science didn’t change. The spotlight did.

But what still needs explaining is why protein matters, which protein matters, and how much you actually need.

And in perfect timing, subscriber mentioned over coffee this past week that she’s looking into regenerative farm “cow share” (for lack of a better phrase) to ensure her family gets clean, grass-fed protein. Yes, this is a real conversation we had. And it made me realize: the word protein is thrown at us constantly, but there is so much nuance here.

“Protein” desperately needs a better explanation.

So let’s break it down…in Monday-friendly English.

Protein Is the Raw Material for Feeling Younger

Protein keeps showing up for one simple reason: it’s the raw material your body uses to stay strong, steady, and resilient.

Protein touches a lot of the things we care about day to day: energy, recovery, mood, blood sugar…and all of that funnels into one place: muscle.

Muscle isn’t about aesthetics (ok, maybe a little); it’s about capability.

It’s what lets you carry groceries without thinking about it, get up off the floor without bracing, feel stable instead of fragile as you age.

Muscle protects your metabolism (it’s a great sugar-sink), supports your hormones, and basically keeps you going as you age. But muscle doesn’t maintain itself intrinsically; it needs building blocks, and those come from protein.

A Quick Biology 101 (I Promise This Is Helpful)

Before we go any further, a quick biology refresher.

Protein isn’t one single thing. It’s made up of amino acids, which are the building blocks your body uses to repair tissue, build muscle, make hormones, and basically keep the whole system running.

You’ll often hear amino acids described as “essential” or “non-essential.” That just means that some your body can make on its own, and some you have to get from food.

And while all amino acids matter, there’s one that deserves a little more attention when we’re talking about muscle, strength, and aging well.

That amino acid is leucine.

The Leucine Layer

Leucine is an essential amino acid, meaning we must get it from our diet (our bodies do not produce it). Leucine is the amino acid that turns the switch to the “on” position for muscle protein synthesis: the process your body uses to build muscle.

Quick tangent, because this matters: when I say “build” muscle, I’m not talking about getting bulky or suddenly busting through your shirt sleeves. I’m talking about the unglamorous basics of repairing, maintaining, and saving up for the future.

Muscle is your buffer. It’s what helps your body handle the inevitable: illness, injury, stress, surgery, or just the normal aging process (which, inconveniently, happens to us all, despite my promising Substack title). The more muscle you go into those moments with, the better off you are on the other side.

For today’s conversation, I’m talking about muscle less as an aesthetic goal (though, of course it is) and more as a rainy-day fund for your body.

Okay, back to leucine.

You can eat “protein” all day long, but without enough leucine in a meal, your muscle doesn’t get a clear message to actually do anything with it.

Research suggests that there’s a meal-level leucine threshold of roughly 2.5 grams of leucine to trigger a muscle-building response. Below that, the signal is weaker; at or above that, your body responds more consistently.

There’s nuance here, as there always is. As we age, muscle becomes a bit more resistant to this signal, which is why studies in older adults often point closer to ~2.8 grams. Younger adults can usually get away with a little less.

This is why many longevity doctors recommend aiming for ~3 grams of leucine per meal. Not because you need exactly three grams per meal, but because it’s already surprisingly hard to get there. If you aim for 3, you’re much more likely to hit the 2.5 threshold. If you aim for 2.5, you’ll often fall short without realizing it.

And there’s another reason you’ll want to get your leucine game going…

A lesser-known part of the leucine story is that it helps more than muscle. Drumroll please…it also helps your body use fat for energy more efficiently.

Leucine activates a pathway in muscle cells called AMPK, which you can think of as your body’s internal fuel gauge. When AMPK is turned on, your body gets better at burning fat, regulating energy, and keeping metabolism flexible.

In plain English: leucine helps you burn fat instead of storing it.

Can You Just Take Leucine by Itself?

Not exactly.

Leucine is the main signal, but muscle protein synthesis is still a team sport. All amino acids play a role…leucine just gives the green light.

Leucine alone doesn’t build muscle, but leucine with the other amino acids makes the signal much clearer. I do personally sprinkle a bit of L-leucine (I use BulkSupplements) into my protein shake as insurance to make sure I cross the threshold alongside a complete protein source. I started doing this around the same time I began lifting heavier, and I do feel it’s amplified my progress in the weight room.

So if leucine is the signal, and you need roughly 2.5 grams per meal to activate it, the next question you’re probably asking yourself is:

“Am I hitting that threshold?”

Maybe. More likely, maybe not. (Oh, just sit down, Instagram)

This is where protein stops being a vague concept and starts being about math, efficiency, and preference.

Protein Sources

Once you understand leucine, the conversation can get very practical.

Some protein sources hit the signal efficiently. Others can get you there, but only with more volume and more calories. Neither is “wrong.”

This is one of those moments where seeing the numbers is far more convincing than anything I could write, so here it is:

As you can see, animal protein hits the leucine mark more efficiently. Plant proteins also do the job, but require more volume. This is why I lean toward animal protein for most meals. Not because plants are “bad,” but because I don’t want six cups of quinoa.

Some Quick Notes

• When it’s easy, I lean toward grass-fed, pasture-raised, organic, and wild-caught animal options because quality adds up over time. This is why Kelly’s grass-fed sourcing comment hit home: if you’re eating something regularly, it’s worth caring a little about where it comes from. That said, consistency beats perfection. Always.

• Collagen not included above because, while it’s technically a protein, it’s missing an essential amino amino acid (tryptophan) and is very low in leucine, so it’s not really “counted.” It’s great for joints, skin, and connective tissue, though! “Put it in your coffee!”

Your Personal Protein Goal

Once you see how different protein sources stack up and how much easier some make it to hit the leucine signal, the next question is pretty obvious:

What does this look like for you?

Most longevity-focused doctors start with this practical guideline:

One gram of protein per pound of your goal body weight per day.

Not your current weight (unless you’re at your ideal weight). Not “high school weight.” Just the weight you’d feel comfortable maintaining. So if your goal weight is 130 lbs, your goal would be roughly 130 grams per day.

Now comes an important caveat.

In certain circumstances, your body is more catabolic than anabolic. This means it’s more likely to break down muscle than build or maintain it.

Most longevity doctors I know recommend aiming at more like 1.2–1.6 grams per pound of goal body weight if you’re in any of the following categories:

• Strength training

• In peri- or menopause

• Recovering from injury or illness

• Using a GLP-1 medication

All of the above increase muscle breakdown, reduce appetite, or make muscle harder to preserve.

• Strength training creates stress on muscle. You need more protein to repair and adapt, otherwise you’re just tearing tissue without rebuilding it.

• Peri/menopause shifts hormones in a way that makes muscle more resistant to growth signals. Protein helps counter that resistance.

• Illness or injury puts your body in repair mode, which dramatically increases protein demand.

• GLP-1s suppress appetite, making it easy to under-eat protein, and though muscle-retention is improving each time a new one hits the market, there is still a good chance of losing muscle alongside fat.

In plain English: in these situations, higher protein is about preventing loss.

A Quick Word on Sarcopenia, Because This Is the Real Issue

There’s a medical term for the gradual loss of muscle as we age: sarcopenia.

Have you ever seen those old women whose knees are the widest things on their legs? Yes, that is a problem that has an actual, named diagnosis. Sarcopenia doesn’t start at age 80. It can start as early as your 30s and accelerates if muscle isn’t actively supported.

Left unchecked, sarcopenia affects strength, balance, metabolism, resilience after illness or injury, and long-term independence. This is why the global health conversation has shifted to “get stronger.” Muscle is now considered the organ of longevity, and protein is one of the simplest ways to protect it. (Strength training is the other. Spoiler alert: we’ll talk about that next Monday.)

Reality Check

Now for the part where I lower my voice.

Even knowing all of this (the leucine math, the protein targets, the longevity logic) I don’t hit my protein goal every day. I try. I care. I know better. And it’s still…hard.

So what I do is the best I can:

• A protein shake at some point during the day. Sometimes two if I’m running around. It’s my easiest insurance policy.

• Goat whey in my coffee. This alone bumps my protein early without requiring a separate meal.

• Skyr yogurt in the morning when it fits. Easy, predictable, no drama.

• A simple rotation for lunch and dinner: fish, chicken, or steak. I don’t get much more creative; unfortunate for my family, yes.

On the weeks I hit my protein more consistently, I notice it: my strength improves, workouts feel more productive, and recovery is easier. It’s really quite the positive feedback loop.

And Now, Back to Where We Started

After all of that… yes, we’ve come full circle.

You’re probably not eating enough protein.

But now it’s not just a loud internet scolding. You know why it matters, what actually counts, and how to approach it.

So this week, you might find yourself nudging up your protein. See how your energy feels, how your body responds, and you might be surprised just where you land by next Monday.

See you then,
Susan

Longevity in the Wild

Last Saturday, my longtime friend, , mentioned that she enrolled in a couple classes at her local university (my alma mater, no less!) that have nothing to do with her job…simply because she’s interested in learning more about a certain topic. What started as a casual update turned into a great reminder.

She said, “curiosity is the key to a fun life.”

She’s right! Learning new things and staying curious helps keep your brain flexible as you age. And while Caroline made it official with classes (honestly, so impressive since she’s a working mom), curiosity doesn’t require a syllabus. A new interest, a new question, a new rabbit hole all count.

People always ask me: “But where do I actually start?” Think about it like choosing between the local train and the express train. (shout out to subscriber, , for this analogy and perfect kickoff question!)

Yes, the express sounds better. Faster! Sleeker! Sexier!
But here’s the thing: the express only works if you already know the route.

If someone hasn’t slept in weeks, hasn’t eaten protein in four days, and is running on caffeine, sugar, adrenaline, and oat milk…peptides, protocols, and recovery tools won’t land.

That’s why today I’ll stay focused on a handful of the basics: seven things I swear by and believe are meaningful and mostly no cost.

THE LOCAL TRAIN

These are the habits that seem almost too simple to matter…until they do.
Small choices, big ripple effects. All backed by research, translated into plain English. And, by the way, you know these things; nothing here is groundbreaking, but sometimes the why is what turns a ‘should do’ into a ‘do.’

Quick note: when you see blue words, you can click on them to go deeper into the science.

1. Go to bed a little earlier

Deep sleep does so many wonderful things. It repairs tissue, consolidates memory, stabilizes hormones, regulates blood sugar, and lowers inflammation, but here’s the catch: this cycle happens early in the night. Once that window closes, your brain can’t “make up for it” later, no matter how long you subsequently sleep. (supported by this deep-sleep timing study…and this one…and this one…and this one — #science).

In plain English: Lights out, screens down by 10pm. Miss the window, miss the deep sleep. Miss the deep sleep, turn on brain fog, fat storage, out-of-whack hormones, and a lowered immune system. Early bedtime: cheapest full-body upgrade available. (I wrote a blog for ResetOne on this very topic)

2. Take a short walk after meals

Even 2–5 minutes of easy walking lowers post-meal glucose spikes. 30 minutes is even better. In fact, walking after eating has shown to have a greater impact on blood sugar than simply reducing carbs…but don’t just take my word for it.

In plain English: Fight the food coma; move a little instead. Got stairs? Even better, go up and down a few times. I’d argue any movement counts actually, even the kitchen cleanup.

3. Have a protein-forward breakfast

I get questions about breakfast in general…to intermittent fast or not to intermittent fast, how much coffee is too much coffee, how bad is it to skip breakfast once in a while? As a former non-breakfast eater (now recovered), I always recommend eating breakfast…but make it full of protein.

Protein earlier in the day = better satiety, better blood sugar, better muscle support, and more lean mass (translation: you’ll look better and feel better).

In plain English: Start your day with protein, and the rest will fall into place. Trust me on this, but do see for yourself. (And before you ask, my favorite quick protein staples are Momentum Shake, Mt. Capra Goat Whey Protein, and Siggi’s Plain Skyr)

4. Hydrate in the morning… and yes, coffee counts

(Hopefully) 8+ hours overnight is a long time to go without hydration, and when you wake up, your cells are screaming for it. Your joints are stiffer, you’ve got toxins to flush out, and your metabolism would like to get a move on already.

You’ve probably heard you should be squeezing half a lemon* into your water and adding a pinch of sea salt. If life is handing you lemons, go for it! It’s just…most of us really just want coffee**. Well, I’ve got some good and breaking news: coffee hydrates like water once you’re habituated.

In plain English: Hydration doesn’t need to be dramatic. Give your body some form of it. Yes, I do like electrolytes in the morning, I throw a packet of unflavored LMNT in my water bottle, especially before a workout, but you could just shake some plain old salt in there, too.

*Surprisingly, lemon is not great for everyone (like me). I’ll get into that another time.

**I will do a WHOLE THING on coffee and what I add into mine in a subsequent post, stay tuned. I happen to think it’s a miracle drug…yes, drug.

5. Step outside for morning sunlight

Paging Dr. , patron saint of “go outside first thing!” He didn’t invent sunrise, but he did manage to cement it in the wellness canon, reminding all of us that the most powerful longevity tools aren’t always the fancy ones.

Morning light locks in your circadian rhythm, steadies cortisol, boosts alertness, improves mood, and cues better melatonin later…all in under two minutes and at exactly zero cost. If you’d like to shed some scientific light on the matter, start with ye olde classic circadian study…then consult the gospel according to Andrew.

In plain English: Morning light (even on cloudy days) is your daily software update. Skip it, and your internal clock drifts. Get it, and your whole day runs more smoothly with suspicious ease.

6. Do (at least) one strength-training day (but not 7)

I have many thoughts about exercise, but I’ll keep this short: muscle may be the single most important organ for longevity, and it only grows when it gets a strong signal. That signal is heavy weight. Heavy enough that your body goes, “Oh, wow,” but not so heavy that your form suffers or you flirt with injury. Turns out, resistance training is medicine.

You might not love it at first: proper strength training is slow, it’s boring, there’s a lot of standing around on purpose. But it is magical. And the secret ingredient, believe it or not, is rest. It took me a while to wrap my head around it, too, so I’ll let it sink in for now and come back with a proper, dedicated explanation another Monday.

In plain English: Heavy weight → strong signal → stronger muscle → younger biology. Lift, rest, repeat. Add more weight/days when you’re ready.

7. Finish dinner a little earlier

Digestion isn’t instant: it takes hours, and your body doesn’t want to still be working on dinner when it’s bedtime. Finishing your last meal 2 (ideally 3) hours before bed gives your system time to process food before your deep-sleep window kicks in (…hey, we’re full circle to #1!).

And these brilliant researchers showed that earlier eating is linked with better glucose control (your blood sugar staying calm), improved metabolic flexibility (your body’s ability to use whatever fuel it gets), and steadier next-day energy (no explanation needed).

In plain English: Let your digestive system clock out early and tag in the Rest and Repair team.

A Quick Reality Check

I don’t hit every habit every single day. I hit most of them most days, and that’s enough to make a difference. Even people like me, like Trish, who are already doing some of the “express” things…we still have our uneven days. So does everyone. It’s not a failure, it’s not a setback; it’s just real life. The basics simply make everything steadier for all of us. I could go on (and on) about other needle-movers, but these are plenty to get started.

And just so it’s said out loud: you don’t need to be perfect or obsessive for longevity to work. The needle moves the moment you simply get started, not when everything is flawless, logged, or optimized.

And because I know some of you are already thinking about the “fun stuff,” YES: the express tools are real, they’re powerful, and they each deserve their own post. For today, here’s a quick snapshot of the express train.

THE EXPRESS TRAIN

The express train is the upgrade: faster, more targeted, but only helpful after the local has given you a foundation. The local train gets everyone on board. The express is for the people who’ve learned the route.

Express looks like:

• peptides

• advanced molecules

• hormone support

• targeted supplements

• biomarker optimization

• structured strength training

• wearable tracking of all the things

• contrast and red light therapy and other recovery tools

This path accelerates your progress, but only once your system has stability. You don’t start here. You gradually get here.

For example, GLP-1s (peptides!) will help with weight loss. But without enough protein, strength training, and basic lifestyle habits underneath, the results can come with sagging skin, stalled metabolism, and a body that doesn’t feel as good as the number on the scale looks.

Do I personally believe GLPs can benefit most people? I do…for many reasons. But using them comes with asterisks and lifestyle prerequisites.

Biomarkers? Incredible tools. Some improve with lifestyle alone; others need molecular backup. I LOVE a molecule. Anyone who’s been in my kitchen has seen the stash. But what you won’t see there is refined sugar, ultra-processed food, or alcohol. Not because I’m a saint, but because my body feels better without them. We’re all a work in progress here.

I’ve learned that even the coolest tools only work well on top of a solid base. So let’s talk about where to begin.

WHERE SHOULD YOU START?

Just start.

Choose one thing.
Just one.
Commit to it.

Then, only when it feels easy, add another thing. Simple. Impactful.

Longevity isn’t all-or-nothing. Some days you need the local. Some days you’re ready for the express. Both move you forward.

And if you stay in motion, in whatever way you can, you’ll feel younger.
Not someday.
By next Monday.

See you then,
Susan

LONGEVITY IN THE WILD

People ask me things all week long. Here’s a highlight from this week:

A very tired new mom noted her brain fog in my presence, and—obviously—I could not keep quiet. My recommendation…creatine: 5mg at minimum, 10mg for greater results, go up to 20mg if you can. “Just throw it in your coffee.” It’s one of the few things that can meaningfully support cognitive performance and the general ability to function in the world when you’re sleep-deprived. And that goes for anyone who had a sleepless night!

People ask me about longevity all the time: what I’m trying, what they should be doing, what actually works, what I recommend, what I’ve stopped doing, and what I’m currently testing on myself, my family, and my bravest friends. At some point, it became clear that instead of answering these questions one text at a time, I should probably just start writing things down.

Some jokingly call me “Dr. Susan” (for the record, I’m not a doctor, though I identify as one in spirit), mostly because I can’t help experimenting, learning, and sharing everything I discover. And since I also work in longevity, I’m immersed in this world every day…reading the research, talking to experts, and watching what actually helps people feel better in real life.

Part of the reason I care so much about this is personal: I’ve been a longtime longevity patient myself, and, now in my mid-40s, I can say without exaggeration that longevity medicine changed my life. It changed how I feel, how I function, and how I think about aging. It showed me that feeling my absolute best is possible with the right information, the right support, and the right choices.

Younger By Monday is where I share that real-life version of longevity. Not the hype, not the noise, just the habits, tools, experiments, questions, and small decisions that have actually helped me feel better, stronger, clearer, and more myself. Expect a blend of science, curiosity, honest reflection, and a tiny bit of magic, because longevity really does live at the intersection of biology and wonder.

This won’t be prescriptive, and it won’t be perfect. But it will be real. I’ll bring the science, the curiosity, and the things I’m learning as I go; you bring your questions and your goals. If you’re here for the “what does this actually mean for me?” version of longevity, you’re in the right place.

Here’s to getting younger…one small choice at a time.
— Susan