Is It Actually Your Cortisol? Cortisol Belly & Cortisol Face
Is cortisol belly real? Is cortisol face? Does a cortisol cocktail do anything? Cortisol is a real hormone with a real job, which is exactly what makes it the perfect wellness villain: invisible, universal, and conveniently testable by whoever is also selling the cure. In this episode we trace the panic back to Hans Selye, the tobacco-funded "father of stress," through a naturopath's self-published adrenal fatigue book, and up to the $4.8 billion cortisol supplement economy. Kylee explains what cortisol actually does, why a single blood draw tells you almost nothing, how doctors really test it, and what the research says about cortisol and exercise, overtraining, and under-fueling. The short version: your cortisol is probably fine. The problem it's being blamed for is usually something else.
- 00:00Cold open: everything is cortisol now
- 02:17Reduce, reuse, recycle: adrenal fatigue gets a new name
- 05:31Hans Selye, the "father of stress," and the tobacco money
- 09:09Adrenal fatigue: a naturopath, a self-published book, and ground-up cow glands
- 12:28Why cortisol became the theory of everything
- 15:43What cortisol actually is: the HPA axis
- 19:12Acute vs. chronic, and why one blood draw doesn't tell you much
- 21:54A day in the life of cortisol
- 24:27Morning routines, sunlight, and the coffee delay
- 27:00Cortisol face vs. moon face
- 29:05Cortisol belly
- 34:03The cortisol cocktail
- 36:14Ashwagandha, magnesium, and "hormone balancing"
- 37:35Can cortisol be too low? Addison's and the flattened curve
- 39:23How doctors actually test cortisol
- 42:06DUTCH tests, hair tests, and the reliability problem
- 45:03Why cortisol is perfect grift material
- 46:04The $4.8 billion cortisol economy
- 50:12Cortisol and exercise: the 20-minute Cushing's comparison
- 53:33Overtraining blunts cortisol; under-fueling raises it
- 58:57What actually helps: sleep, carbs, recovery
- 62:20Bottom line
- Is cortisol belly real
- Cortisol face and moon face
- Cushing's syndrome vs. everyday stress
- The cortisol cocktail
- Adrenal fatigue (and why it doesn't exist)
- Hans Selye and the tobacco industry
- What the HPA axis does
- The cortisol awakening response
- Acute vs. chronic cortisol
- How doctors test cortisol
- DUTCH tests and hair tests
- Cortisol supplements: ashwagandha, magnesium, L-theanine
- Bovine adrenal extract
- Addison's disease
- Cortisol and exercise
- Overtraining and blunted cortisol
- RED-S, under-fueling, and elevated cortisol
- Carbohydrates, amenorrhea, and the stress response
- Menopause, lifting, and the "don't spike your cortisol" myth
- The cortisol supplement market
- Cadegiani, F. A., & Kater, C. E. (2016). Adrenal fatigue does not exist: A systematic review. BMC Endocrine Disorders, 16, 48.
- Cadegiani, F. A., & Kater, C. E. (2017). Hormonal aspects of overtraining syndrome: A systematic review. BMC Sports Science, Medicine and Rehabilitation, 9, 14.
- Endocrine Society. (n.d.). Adrenal fatigue [Patient resource]. https://www.endocrine.org
- Kudielka, B. M., Broderick, J. E., & Kirschbaum, C. (2003). Compliance with saliva sampling protocols: Electronic monitoring reveals invalid cortisol daytime profiles in noncompliant subjects. Psychosomatic Medicine, 65(2), 313–319.
- Lopresti, A. L., Smith, S. J., Malvi, H., & Kodgule, R. (2019). An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: A randomized, double-blind, placebo-controlled study. Medicine, 98(37), e17186.
- Meeusen, R., Duclos, M., Foster, C., et al. (2013). Prevention, diagnosis, and treatment of the overtraining syndrome: Joint consensus statement of the European College of Sport Science and the American College of Sports Medicine. Medicine & Science in Sports & Exercise, 45(1), 186–205.
- Mountjoy, M., Ackerman, K. E., Bailey, D. M., et al. (2023). 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine, 57(17), 1073–1097.
- Petticrew, M. P., & Lee, K. (2011). The "father of stress" meets "big tobacco": Hans Selye and the tobacco industry. American Journal of Public Health, 101(3), 411–418.
- Selye, H. (1936). A syndrome produced by diverse nocuous agents. Nature, 138, 32.
- Stalder, T., Kirschbaum, C., Kudielka, B. M., et al. (2016). Assessment of the cortisol awakening response: Expert consensus guidelines. Psychoneuroendocrinology, 63, 414–432.
- Wilson, J. L. (2001). Adrenal fatigue: The 21st century stress syndrome. Smart Publications.
Cold open: everything is cortisol now
Kylee: Welcome to Your Diet Sucks, the podcast that won't sell you a $54 mocktail to fix a hormone you're measuring wrong. I'm Kylee Van Horn.
Zoë: And I'm Zoë Rom.
Kylee: Zoë, I'm curious. In the last six months to a year, how many times has someone told you a health issue you're having could be your cortisol?
Zoë: A hundred percent, because I'm a slightly stressed-out woman. Obviously some sort of cortisol imbalance is the root cause of every physical and mental ailment I've had, and probably also my financial woes and relationship problems if we're taking it all the way.
Kylee: It's all-encompassing. It all goes back to cortisol. Symptom-wise, what do people hear? Puffiness, inflammation, sleep issues?
Zoë: I hear it constantly. If you're tired, it's probably your cortisol. Sleeping too much or not enough, cortisol. Face looks a little inflamed, cortisol. Not hungry or too hungry, cortisol. Issues with your hair, teeth, skin, nails, life: all of it, probably cortisol. The thing I really want to untangle today is that a lot of this is aimed at women as they age, and the way it's gotten caught up in exercise and fitness troubles me, because there are ways it could actually encourage women to exercise less.
Kylee: And it tries to sell you things you don't need. The adaptogen lattes.
Zoë: Exactly. The word "nootropics" comes to mind. There are so many fixes and powders and gummies for cortisol. We did an episode over a year ago about whether you can hack your hormones, but cortisol keeps coming up as the boogeyman for any issue an athlete can have.
Reduce, reuse, recycle: adrenal fatigue gets a new name
Kylee: How did we get from cortisol being a hormone we'd die without to cortisol being a thing someone on TikTok says is wrecking your face? Is this new, or are we recycling an idea?
Zoë: Reduce, reuse, recycle the same wellness ideas over and over. Historically, the cortisol story is a rerun of every other wellness boogeyman. You could make it a Mad Lib and sub in "inflammation." For twenty years the wellness industry sold adrenal fatigue, which every endocrinologist says doesn't exist. One of my favorite paper titles of all time is the systematic review literally called "Adrenal Fatigue Does Not Exist." We love a petty title. And I think wellness culture plugged cortisol into that slot to make it feel more science-y. Same vague symptom list, same supplements, same tests, now bolted onto a hormone that is real and does have actual functions in the body. That's where it gets confusing, even for me. We can't debunk cortisol the way we debunked adrenal fatigue, because cortisol is real. It spikes when you're stressed. At the extreme it can make your face puffy. But it's also the perfect diet-culture villain. It's invisible, so you need a test, which very conveniently someone will sell you. Looking at you, hair-test companies in Florida. It's universal, because everyone feels stressed, and it's reassuring to hang that disembodied feeling on a peg. So the market for cortisol supplements is everyone. It bundles the three things wellness is best at monetizing: weight, energy, and your appearance. And it lets you sell a diet as "nervous system regulation." Calm becomes a moral achievement and being stressed becomes a personal failing, which is convenient if the real cause of your stress is a job and a toddler and rent and a parent you're caring for, none of which a green powder can fix.
Hans Selye, the "father of stress," and the tobacco money
Kylee: Where does the idea that stress kills you or causes health issues even come from?
Zoë: It feels ancient, but it's about 80 years old. The concept of stress as a thing that wears your body out was basically invented by one man: Hans Selye, the self-described "father of stress," which is a heck of a title. If it were me I'd just go with "stress daddy." He built the idea in the 1930s and 40s doing extremely upsetting things to rats, then sold it to the public in something like 39 books. Before Selye, "stress" was an engineering word for the load on a bridge. He was the first person to say: bridge, body.
Kylee: Never thought of those two together, but sure.
Zoë: There are days I feel like a human bridge holding too much together. Here's the part that should raise hackles: starting in 1958, Selye took money from the tobacco industry. At the peak he was pulling in about $50,000 a year from the industry-backed Council for Tobacco Research, which is almost a quarter of a million dollars today. And his stress research got used again and again in court to argue that smoking didn't cause heart disease or cancer. The pitch, straight from an internal industry memo, was that stress is what makes you sick, and smoking is just an acceptable way to relieve it.
Kylee: Is that why cigarettes are coming back?
Zoë: Gen Z is like, what do we want to bring back? Ill-fitting jeans and cigarettes. He never disclosed the tobacco money, which is not how things should work. And the reason I bring it up is that the frame the entire cortisol industrial complex runs on, stress is the hidden thing killing you, was originally funded and shaped by big tobacco to get people to stop blaming cigarettes. When you trace the lineage of that $54 mocktail, it's the same move: don't look at the underlying causes, point at one boogeyman.
Adrenal fatigue: a naturopath, a self-published book, and ground-up cow glands
Kylee: Moving along the timeline, when does adrenal fatigue actually show up?
Zoë: Much like JNCO jeans, it popped up in the late 90s. A naturopath named James Wilson coined "adrenal fatigue" in a self-published book. "Naturopath" and "self-published" should both lodge somewhere.
Kylee: When are you coming up with your own vocabulary in a self-published book?
Zoë: Zoë-isms. I have Bowie fatigue. His theory was that chronic stress runs your adrenal glands until they're too tired to make cortisol, so you're wiped out but also overwired and somehow craving salt. The symptom list is literally everything, the same list on every TikTok today: fatigue, brain fog, sleeping badly, sleeping too well, body aches, gut problems, needing coffee in the morning. That describes everyone I know. When you make the lens so wide that every person on Earth falls in, that's a grift. It got a huge boost from Dr. Oz around 2015 and was carried by functional medicine for years.
Kylee: Dr. Oz, who's back in the spotlight in the current administration.
Zoë: For all the worst reasons. Endocrinologists dismissed it. The Endocrine Society said flat out there's no proof adrenal fatigue exists. A 2016 systematic review found nothing, and the mechanism actually runs backwards: under real stress your adrenals make more cortisol, not less. They don't run out. And the treatment was harmful too, because it originally included bovine adrenal extract. Ground-up cow adrenal glands, sold as a supplement, containing real steroid hormones in doses nobody was checking, because this was after DSHEA. They're still sold. Take enough and you can suppress your own adrenal function and manufacture the exact problem the label invented. Meanwhile the real causes of your exhaustion, thyroid disease, depression, sleep apnea, anemia, late capitalism, never get addressed.
Why cortisol became the theory of everything
Kylee: Before we get into what cortisol actually is: what does it say about us that "it's your cortisol" is the answer we reach for?
Zoë: People needed a name for the feeling that modern life is too much. And cortisol sounds more legitimate than a vague sense of ennui. That's what Selye did: he took a common human experience, being worn down by life, and gave it a biological address. Once it has an address you can test it, treat it, and sell a cure. What cortisol really is, and the thread we'll keep pulling today, is the place where a structural problem gets relocated onto the individual body. Maybe your job is unsustainable and you're doing too much childcare and your rent went up. What does the wellness industry do? It hands you a gummy. The gummy can't fix any of that, but it can be purchased, and it makes you feel like you're taking back control. There's a status signal too. "I'm regulating my nervous system" is the new "I'm so busy." At peak hustle culture, being visibly stressed was an achievement. Now calm is the flex. What "my cortisol is dysregulated" does is convenient: it turns a lot of problems into one problem you can dose your way out of rather than investigate. But I do want to know what cortisol actually is. I know she's a hormone. Beyond that, I don't know who she is or where she comes from.
Kylee: It's a she.
Zoë: Obviously.
What cortisol actually is: the HPA axis
Kylee: Cortisol is a steroid hormone made by the adrenal glands, so there's a real connection to that adrenal fatigue idea. The adrenals are little caps that sit on top of your kidneys. It runs on a feedback loop called the HPA axis: the hypothalamic-pituitary-adrenal axis. Your brain's hypothalamus signals the pituitary, the pituitary signals the adrenals, the adrenals make cortisol, and cortisol circles back and tells the brain to ease off. The off switch matters a lot. It's a thermostat.
Zoë: So it's self-regulating, which already makes me skeptical of exterior products promising to regulate a thing that seems pretty good at regulating itself.
Kylee: Exactly. In the moment, cortisol dumps glucose into your blood so muscles and brain have fuel, raises your blood pressure, sharpens your focus, and turns down whatever you don't need in an emergency.
Zoë: So if I'm running from a bear, my brain says there's a bear, raise cortisol, and now I have more glucose available to run.
Kylee: And you're probably not thinking about reproduction in that moment. Digestion, immune activity, and reproduction get turned down. It's also one of your main anti-inflammatory signals. That's why the synthetic version, a cortisone shot, calms things down. Cortisone is cortisol. It's a steroid.
Zoë: I've never made that connection until right now. One more thing showing this is more nuanced than "cortisol bad."
Kylee: Throughout the day, in the morning cortisol should be high to get you going, and at night it should drop to help you sleep. And you would die without it. People who can't make cortisol have an actual disease: Addison's disease.
Zoë: So it's a self-regulating system that for most people is genuinely not a problem. What frustrates me is that online, any fluctuation gets treated as inherently bad. You messed up, you made yourself stressed, your cortisol spiked.
Acute vs. chronic, and why one blood draw doesn't tell you much
Kylee: That's where people get a cortisol marker on a blood panel, and it's on the InsideTracker panels and standard panels, and the hard thing is that's one point in time. While you're getting your blood drawn, which if you're me means you're a little stressed. The main point is the difference between acute and chronic. Everyone has their own rhythm. In general you want it higher in the morning and lower in the evening. A spike that comes and then leaves means the system is working. If it's high for a long period, the system might be stuck. Chronic versus acute, like inflammation.
Zoë: Simplistically: the right amount is good, chronically elevated is bad, but it's not that any amount is poison.
Kylee: If something needs you to work a little harder, it's supposed to come up and then drop down.
Zoë: Like public speaking. I get anxious before stand-up. My cortisol probably goes up before I do comedy, but I don't feel that way all the time.
Kylee: If you were that way all the time, that's chronic, and then we could see real impacts on sleep, blood pressure, blood sugar. "Cortisol is bad" is like saying water is bad. One glass keeps you alive. Forty glasses is a problem.
Zoë: That's what social media and the wellness industry get wrong again and again: there's a Goldilocks zone.
Kylee: And then the supplement industry dives in: your cortisol is chronically elevated, you need a supplement to turn the whole system down. That's missing some key pieces.
A day in the life of cortisol
Zoë: What does a day in the life of cortisol look like? I'm picturing the opening of every 90s movie. Little Miss Cortisol.
Kylee: Times vary by person because everyone's circadian rhythm is a little different, but say it's you. Around four or five in the morning, maybe three for you, cortisol starts climbing on its own. No stressor required. It peaks 30 to 45 minutes after you wake up. That's the cortisol awakening response. Some of these terms start sounding medical, and testing companies will say "your cortisol awakening response is off," and I'm like, what does that mean?
Zoë: Just because it has a name doesn't mean we need to pathologize it.
Kylee: That spike is important. It gets you out of bed and moving. Then it drifts down and bottoms out at night so melatonin can take over. That rise-and-fall shape is the whole point. When a doctor tests cortisol properly, they read the shape of the curve across the day, not one number on its own.
Zoë: It really varies. Cortisol can drop to levels roughly four to fifteen times lower at midnight than at the morning peak. That's not a subtle fluctuation. That's a big natural wave, because there are times you want to lock in and times you want to lock out so you can eat a meal or go the fuck to sleep. So where do things start going awry in wellness culture?
Morning routines, sunlight, and the coffee delay
Kylee: Right in the morning. Right when you wake up.
Zoë: It's like showing your work in math. The wellness industry gets lost at the third or fourth step. You wrote the wrong numbers down.
Kylee: A ton of the "fix your cortisol" content is about the morning. Don't look at a screen, get sunlight immediately, and don't have coffee, you have to wait.
Zoë: Quick plug for our Patreon: I wrote an entire blog post on the morning coffee delay myth.
Kylee: Morning light is a good thing. Maybe not checking your phone every five seconds the minute you wake up.
Zoë: The thing my cortisol does not need the second I wake up is what's happening in the Strait of Hormuz. That has never helped.
Kylee: It's not that we shouldn't pay attention to it. It's over-emphasized in the wellness context.
Zoë: You're not going to die if you don't take a mindfulness walk as the first rays of sun crest the valley wall.
Kylee: You don't need a crazy routine to function as a human. How many steps is yours?
Zoë: Wake up. Get out of bed. Should there be more? I make coffee and eat breakfast.
Kylee: I've been on trips with people where it takes an hour.
Zoë: We just went on a trip together and we're both fast. Maybe too fast. For me the big part of my routine is coffee and The Daily. I have to start my day with Michael Barbaro. And we go outside with the dogs. Fresh air and sunlight are good. It's just not correct to say it's evolutionarily something you absolutely need to function.
Kylee: I hate it in the middle of winter when the sun's not up and I'm freezing.
Cortisol face vs. moon face
Zoë: Another one I hear all the freaking time: cortisol face. Before-and-after photos of girlies on wellness journeys to de-puff their faces. This idea that cortisol makes your face perpetually puffy, that you can use it as a diagnostic tool, and that you can learn about it from Courtney on the internet.
Kylee: Cortisol face is borrowing from an actual thing. The clinical name is moon face.
Zoë: That sounds even faker. Whoever named moon face, we've got to workshop this.
Kylee: Talk to whoever named Cushing's syndrome. Cushing's is a rare, long-term condition. It's not that you got stressed once on a Monday and now you have moon face.
Zoë: This is a diagnosed illness, and you know when you have it. It's not something to self-diagnose with a TikTok or a BuzzFeed quiz.
Kylee: If you truly had sustained high cortisol for months on end, it could cause facial swelling. But that's not what's happening in the "cortisol face" content. What's actually happening is kind of boring. When you're stressed you often crave salty, carb-heavy foods. Not a bad thing. But more sodium and carbohydrate coming in can mean more fluid retention, and water tends to show in the face first. Especially if you're like me and sleep face down.
Cortisol belly
Zoë: The other big one, especially for peri- and postmenopausal athletes, is cortisol belly. This one makes me want to scream. The claim is that cortisol makes you gain weight and your body hoards it around your midsection.
Kylee: There is something real underneath. In Cushing's disease, or with long-term high-dose steroids, the body does shift fat toward the midsection. Visceral fat, the fat around your organs, carries more cortisol receptors than fat elsewhere. Cushing's is good evidence that cortisol can drive central fat. But again, that's at a clinical level.
Zoë: You have a diagnosed illness.
Kylee: For a person with normal cortisol and a stressful life, the idea that cortisol is directly inflating your stomach isn't well supported. And I wonder, since we talked about this in our menopause episode, whether people are conflating shifting estrogen and other hormones, which do change body composition, with cortisol, and calling it cortisol belly.
Zoë: I've seen it put as bluntly as "don't lift heavy weights because you'll spike cortisol and gain belly fat." Women on Reddit discussing how to work out in a way that won't give them belly fat. If you're peri- or postmenopausal there could be other things in your life driving stress, and not sleeping and having too much on your plate might change how you eat, things way upstream of "cortisol belly."
Kylee: You could be chronically stressed, which wrecks your sleep, which drives appetite and cravings and cuts your activity. Things get tangled, people want a simple answer, and "it's cortisol" is right there.
Zoë: Because then you can nip it in the bud with a cortisol supplement. And it's always aimed at women, especially as they age. It's the same one-two punch: take plain weight-loss dieting, which a lot of us have been trained to recognize and reject, and dress it up as hormone health. You're not dieting, you're balancing your hormones. Cutting out carbs isn't a diet, it's lowering your cortisol. Same restriction, more palatable language. When you type "cortisol belly" into Google, the top hits are affiliate links and supplements. There are significantly more pathways to buying a thing than to reading a paper, and that's a good data point. The end-all of this show is not to teach people to flatten their stomachs. There's an entire industry that has decided women's midsections are the battleground on which we fight stress. We can't have the conversation about dismantling the structures that make people's lives unsustainable, so instead it's: don't gain weight. I reject that premise. Okay. You have the spike in the morning. What brings it back down?
The cortisol cocktail
Kylee: Hopefully recovery. Or, if you want real recovery, you need a cortisol cocktail.
Zoë: Can you get it at TGI Fridays? Does it come in a tiki glass? I'm sure there's one called the Midsection Blaster.
Kylee: It has orange juice, which I'm not sure the Midsection Blaster would. Orange juice, coconut water, a pinch of salt, sometimes magnesium. To me, that's an electrolyte drink.
Zoë: That sounds like the four most boring ingredients I could find in my fridge after a night out.
Kylee: You could put a Gatorade in a wine glass. And there's no published research, shocking, showing this drink moves your actual cortisol.
Zoë: It's usually one small tart cherry juice study and then, sure, it can maybe do something.
Kylee: Coconut water has electrolytes. Great. It might help if you're dehydrated or under-fueled. It is not going to hack your cortisol.
Zoë: We love the idea that we can mocktail or supplement-stack our way out of something, when it might just be: you need water. Or food. If taking three minutes to do one nice thing for yourself is the only thing holding you together, your cortisol is probably not the issue.
Ashwagandha, magnesium, and "hormone balancing"
Zoë: Last stop on this cursed cortisol journey: what happens when the spikes don't stop and there's no recovery, and where "hormone balancing" comes in.
Kylee: We're talking about the supplements. It's honestly a lot of marketing with a tiny bit of real research. Ashwagandha has some small trials suggesting it helps balance the HPA axis. Magnesium has some small trials hinting it might lower cortisol. But the trials are small, short, and need replication before anyone can build anything on them.
Zoë: So the takeaway isn't that we all need to be snorting ashwagandha. It's that we need more research.
Kylee: And go eat some magnesium-containing foods. Do we need to be macro-dosing magnesium? Probably not.
Can cortisol be too low? Addison's and the flattened curve
Zoë: Can it go the other way? Can you burn yourself to the ground? I feel like I've been there, when I was working on the TV show and commuting to the Front Range every week. Between escaping a hungry animal and driving I-70 in the snow, hungry animal every time.
Kylee: It can be lowered, but not the way people describe it online. A real cortisol deficiency is Addison's disease. It's rare and serious and you need a medical doctor.
Zoë: So the subclinical "chronically stressed but not in a medical way" version isn't really a thing.
Kylee: What the research does look at is a flattened or blunted curve: less of a difference between morning and night, not getting that big dose when you wake up. That's not your adrenals running out of fuel, which is what adrenal fatigue plays off of. It's that the feedback loop gets worn down by repeated or sustained stress, and the response dampens. They see this in people who've been in war zones and have PTSD.
How doctors actually test cortisol
Zoë: Practically, let's pretend I'm a normal person. Imagine, if you can, that I'm a little anxious. How would I know if my cortisol was unhelpfully high?
Kylee: That's where the problems come in. The wellness symptoms, puffy, brain fog, tired, could point to anything. Genuinely high cortisol, Cushing's territory, is something a doctor recognizes: moon face, muscle weakness, easy bruising, high blood pressure. It's not "I'm feeling a little off." And a single high reading isn't a diagnosis. Cortisol is supposed to be high in the morning.
Zoë: Say I have a genuine reason to think it's out of whack. How does a medical professional, not Courtney on TikTok, find out?
Kylee: A doctor could order a blood draw, and I've had doctors order a single cortisol blood draw, which I still can't fully piece together, because the true test is a validated 24-hour urine test.
Zoë: That's got to be a very large Pepsi bottle.
Kylee: Sometimes saliva at specific times, and sometimes dynamic testing where they give you a drug and watch whether your cortisol responds the way it should. Which sounds medical, meaning you go to a medical doctor.
DUTCH tests, hair tests, and the reliability problem
Zoë: When does it tip into full wellness-grifter territory?
Kylee: When you get into "map your whole daily curve and it should look this way." That's often the DUTCH test, multiple saliva samples across the day, sometimes urine. They can be $500, you can get them from a non-medical professional, and then people interpret the results themselves or with someone who isn't a clinician, and get confused about what they're seeing.
Zoë: And the companies offering the test are usually also offering the supplement. I'm ambivalent. Our healthcare system feels irreparably broken, and I like the idea of giving people agency and diagnostic tools. But when you look at the research, putting those tools in people's hands so often doesn't yield better outcomes, because Zoë Schmo is not good at interpreting them.
Kylee: There are studies where about 40 percent of people botch the timing of the samples, and timing matters. And a meta-analysis of the diurnal cortisol measures, including the cortisol awakening response, found poor day-to-day reliability. Test the same healthy person on two different days and you can get two different curves with nothing about their health changed.
Zoë: So the number might not even be measuring the thing in my body consistently, let alone telling me to buy something. You might as well pick a number out of a hat.
Kylee: And that bioresonance hair test from a previous episode claimed to measure cortisol in your hair.
Zoë: And melatonin. Neither of which you can measure in hair that way. And I mailed it in a regular-ass Ziploc bag with a Post-it note. So it's still some random dude collecting hair in Florida.
Why cortisol is perfect grift material
Zoë: Zooming out, why is cortisol such rich ground for grifters? Estrogen and testosterone are hormones too, but they don't get the same treatment.
Kylee: With cortisol it's invisible, so you can't disprove the claim by looking, which means you need the test. It's universal because everyone feels stressed, so the market is everyone. It has a real mechanism to borrow credibility from. And it connects to everything people already worry about: weight, sleep, energy, mood.
Zoë: Aging. How you look. It becomes people's theory of everything. What is the meaning of life? Cortisol.
The $4.8 billion cortisol economy
Zoë: If we follow the money, how big is the cortisol industrial complex? My guess is one billion dollars.
Kylee: You'd be incorrect. It was higher than I expected: $4.8 billion in 2025, and projected to keep growing into the 2030s.
Zoë: I'm used to seeing the ma-and-pa grifters on TikTok, but this sounds like big business.
Kylee: The big brands too. Ritual has a stress capsule positioned around healthy cortisol levels. Nestlé Health Science put ashwagandha and magnesium blends under the Vital Proteins line. Pfizer's Centrum and Unilever's Olly have cortisol formulations.
Zoë: Of course they do. I feel the pull too. Whenever I see the vitamin gummy that says "stress management," it's so tempting to believe I can pop a pill rather than go to therapy, set boundaries, not take on more work than I need, and shred the patriarchy so we get equitable pay.
Kylee: I've taken ashwagandha for stress. The tea with the stress-reducing compounds.
Zoë: For us normie stressy girls, what does this look like where the rubber meets the road?
Kylee: Search "cortisol calm" on Amazon. Over a hundred products fighting for one keyword, and top sellers move tens of thousands of units a month. Ashwagandha, L-theanine, magnesium, lemon balm, GABA, in gummies, powders, capsules. And bovine adrenal extract is still in there.
Zoë: Now I want to double-check everything I'm taking. And then there are the affiliate review sites.
Kylee: "Best cortisol supplements of 2026," ranked, with an affiliate link on every pick.
Zoë: I can hear Rich Roll whispering it into my ear. So it's not just brands. There's a whole content ecosystem creating the problem and the poor diagnostic tools, and that's the fertile ground these products get seeded into. A stress gummy or a course reads like a friend helping a friend. It feels less grifty than a weight-loss energy supplement, which always reads like a gas station from hell.
Kylee: It feels very 21st century. Everyone knows what being stressed feels like.
Cortisol and exercise: the 20-minute Cushing's comparison
Zoë: As an athlete, cortisol comes up again and again. Is there an athlete-specific strain? My cursed TikTok feed is full of fitness people terrified of their own cortisol, or telling menopausal women not to lift weights, which gets you edited right out of my feed.
Kylee: The athlete framing gets it backwards. Exercise raises cortisol, and that's a normal, necessary response. A hard workout is supposed to spike your cortisol. That's how you adapt to training stress.
Zoë: So how did people worried about cortisol end up avoiding the exact thing that helps them?
Kylee: They worry that an intensity session or a long run will spike cortisol and do damage, or get them stuck in a cycle, or lead to the weight gain they're scared of.
Zoë: How big is that spike? Online it's always "spike," never "raises." Never "hormones associated with adaptation." The loaded language is informative. Even "the stress hormone" bugs me, because stress isn't always bad. It's a necessary part of adapting.
Kylee: There was a 2005 study in Biology of Sport. Unfortunately they only used trained men.
Zoë: Stressed women exist too. We're out here.
Kylee: They measured cortisol in trained men after about 85 minutes of hard endurance exercise and compared it to resting cortisol in actual Cushing's patients.
Zoë: I love a study that answers exactly the question I asked. So the internet is right that it raises cortisol. How high?
Kylee: A hard session can briefly push you into the Cushing's range for about 20 minutes. The finding that matters is the second half: the exercise response is transient and drops fast. A Cushing's patient lives there. An athlete touches it for the back half of a workout and is back to baseline in a few hours. The online version gets the mechanism backwards: it says you stay at Cushing's levels forever and it's causing damage.
Overtraining blunts cortisol; under-fueling raises it
Zoë: Walk me through how this can actually go wrong for athletes.
Kylee: The first is true overtraining, which we need to do an episode on because it's poorly understood. Theoretically it's months of training load without proper recovery, not one crappy Wednesday. The surprising part in the research is that cortisol doesn't stay high. The response gets blunted. The system stops reacting.
Zoë: So it's like insulin sensitivity: when your body has had the same response so many times, it winds it down.
Kylee: Give a well-recovered athlete a stress test and cortisol and testosterone climb like they should. Give an overtrained athlete the same test and you get a much smaller hormonal response.
Zoë: So it's not fair to say overtraining is too much cortisol. It's almost the opposite: an inability to raise cortisol, because the system is worn down to the point where it can't respond to the stimulus.
Kylee: Which is the opposite of what the "cortisol-conscious" content implies. It's not that hard effort floods you with cortisol and causes damage. It's that without recovery, the whole stress response starts to malfunction in the same blunted direction we talked about with chronic trauma and PTSD. Same axis. And the second one, the one I worry about most for our listeners, is the RED-S side, which moves cortisol the other way. Up. And it stays up.
Zoë: So overtraining blunts the response and under-fueling raises baseline. Different things that intermingle, because people who are overtrained are often also under-fueling. And the under-fueling piece matters especially because so many "hormone balancing" protocols are diets that end up restrictive.
Kylee: That's the problem. If you lump them together as one vague training-stress problem, it's useless, because they're opposites. The research on low energy availability finds cortisol climbing while the rest of the system slows down, because chronic under-fueling reads to your body as an ongoing threat, not a single workout.
Zoë: So your body's like, we've been in this state for so long, we are still escalating the alarm.
Kylee: If you have an athlete who's overtrained and under-fueled, you get a stress system that's simultaneously worn down and running hot. And the fix is not an adrenal cocktail, and it's not avoiding hard workouts. Have you had athletes say they're worried about doing intensity because they'll gain weight or can't handle the stress?
Zoë: Totally. Athletes I coach will build a narrative around a threshold: if I run four or more days a week, this will happen. If I run more than 25 miles a week, this will happen. But your capacity should be expanding. You get fitter, your ability to withstand load increases, and recovery is where we intentionally build that. Your body doesn't have a hard rule where Kylee ran ten hours this week, time to pull the fire alarm. People get hooked on the simple cause and effect.
Kylee: Side note, a coach can be really helpful, because they periodize training in a way that makes sense for you, not just every four to six weeks but within a week. If your foot is always on the gas, you're not giving your body time to recover.
What actually helps: sleep, carbs, recovery
Zoë: So what actually helps you have healthy, beautifully fluctuating cortisol, if it's not a gummy or a mocktail with OJ for some reason?
Kylee: I'll give you a couple of guesses.
Zoë: Someday I want us to make an episode where we don't tell people to eat, sleep, and periodize their training. Just for fun. "Actually, this powder will straight up do it for you."
Kylee: Sleep first. Some people struggle with quality sleep, and that makes an appropriate cortisol rhythm harder.
Zoë: I relate. My sleep's not great, but I've gotten better at the auxiliary things. I hate the phrase "mindfulness practice," but I've got that going now.
Kylee: Then fueling, and specifically enough carbohydrate. The body reads not having enough carbohydrate as stress, which can raise cortisol.
Zoë: So not just total energy but specifically carbs. Could keto and paleo people have elevated cortisol from not enough carbs?
Kylee: Potentially, but I don't want to over-generalize, because there may be a genetic component that lets some people adapt differently. The individual response varies. We see it directly with amenorrhea, though. If you're not getting enough calories or carbohydrate, the HPA axis feels unsafe and doesn't turn on the reproductive process. Feed someone enough, particularly carbohydrate, and it helps turn the system back on. And it goes down to timing. If someone gets all their carbs in two meals with a huge gap in between, that can still read as too stressful for a body already in that state. Frequent carb intake.
Bottom line
Zoë: So what's the bottom line, besides eat, drink, sleep, have a carb?
Kylee: Skip the mocktail. Your cortisol is probably fine, and it's doing what it's meant to do. It goes up when you're stressed, drops at night, and helps you get up in the morning. The problem usually isn't your cortisol. It's the things people don't want to hear: you're tired, you're not fueling enough, you're overbooking yourself. And that's a bigger problem to solve.
Zoë: So disappointing. I was hoping I could take a supplement and call it a day.
