by Brian Dunning
September 22, 2026
We all see ourselves in the mirror every day, and most of us see something we don’t like or we wish were better. That’s OK, it’s just human nature; but it can very easily spiral out of being OK and can cause us potentially serious physical and psychological problems if we take our body image so seriously that we start adopting drastic means to change it. Clever marketers know this, and so they appeal to our desire for an easy fix to complicated problems. Often this means inventing a boogeyman that’s said to be the cause of all our problems, blaming that, and coming up with some new brand of snake oil to address it. This year that boogeyman is cortisol, and the snake oil comes in many forms including supplements, diets, books, and regimens all designed to leave you with less money and less cortisol. The problem is they actually take only one of those.
Cortisol is a steroid hormone naturally produced in the body. It has three basic functions: First, it allocates resources by telling the liver when to produce more glucose, and it also draws amino acids and fatty acids out of tissue to provide the liver with the raw materials it needs to make that glucose. Second, cortisol restrains the immune system from creating too much inflammation, and also has other functions which keep blood vessels responsive to adrenaline. Without cortisol doing this for you, adrenaline — when you need it — wouldn’t do anything.
Cortisol’s third function might be the most familiar. It’s a stress hormone, but a very slow one. When your body goes into an acute stress response, adrenaline goes to work within seconds doing everything to prepare your body for fight or flight. Cortisol is also released, but its function happens within cells, and can take hours to have any effect.
The way cortisol is released by the adrenal glands is weird. It is not released continuously over the course of the day, but in 15-20 surges throughout the day. About a third of these surges cluster in the morning hours before and after you wake up. Since the levels naturally fluctuate a lot throughout the day, any given measurement of your cortisol level is essentially meaningless — anything between 3 and 25 µg/dL over the course of an entire day is normal in the blood, and 0 to 3 µg/dL in the saliva. Those are huge ranges, and an hour later it’s probably going to be radically different. So please do not ever depend on some advice for which supplement you need to buy based on your cortisol level. Another common product they’re trying to sell you is a home cortisol test kit; they probably tell you to measure it in the morning, when it will almost always be high; and then they try to get you to buy whatever worthless supplement they promise will lower your cortisol levels.
The other thing cortisol is used for is as a drug. When provided by a pharmacist, the exact same cortisol molecule is called hydrocortisone. It’s a widely-used corticosteroid given for anti-inflammatory or immune suppression purposes. You may have been given this for some allergic reaction like poison ivy or poison oak. Hydrocortisone is also given to people who have reduced adrenal gland function and who don’t produce enough cortisol. It’s given to them because not having enough cortisol is potentially fatal.
So what relationship does this normal, natural compound have with a big fat belly? If you listen to the Internet’s wellness influencers and supplement sellers, you’ve heard that persistently elevated cortisol levels are the major cause of weight gain, especially in men. This is mostly false, but not entirely: the kernel of truth that makes the product pitches sound legit is that cortisol does indeed regulate glucose and fat metabolism, so there’s your relationship. Cushing’s syndrome, which includes elevated cortisol, does result in higher body fat and muscle loss — but it’s also rare. The biggest problem with drawing this link is that the direction of causation is actually not known.
Being overweight — having a lot of adipose tissue — results in more cortisol in your fat, not the other way around. The mechanism for this has to do with cortisone being a metabolite of cortisol, and some of that cortisone is always circulating in your blood. Adipose tissue contains an enzyme called 11β-HSD1. This enzyme converts that circulating cortisone back into active cortisol inside the fat tissue. The heavier you are, i.e. the more adipose tissue you have, the more cortisol is being reactivated in your fat tissue. It’s still not clear which effect is larger (if either): cortisol increasing fat, or fat increasing cortisol!
In fact, the idea that reducing cortisol will help you lose weight has already been put to a large-scale test, and failed completely. In the 2000s, researchers studied this action of 11β-HSD1 reactivating cortisol, and wanted to find out if inhibiting the 11β-HSD1 would reduce the amount of cortisol in the fat tissue and thus trigger weight loss. Pharmaceutical companies — always desperate to find some effective weight loss drug — performed clinical trials with a number of 11β-HSD1 inhibitors. Any improvement was statistically insignificant, and gave us no new weight loss drugs. So any wellness influencers telling you that whatever magical supplement they have will reduce your cortisol and thus reduce your weight have either done no homework at all and not learned some basic fundamentals of the product they’re selling you, or are openly lying about it.
There’s another little tidbit here that’s worthy of a mention in case you are dead set on reducing your cortisol levels. When cortisol levels are lower than the body tries to establish, that’s called Addison’s disease. It causes fatigue, low blood pressure, low sodium, low blood sugar, and death if untreated. So just to reiterate: reducing cortisol should never be anyone’s goal. It reminds me of how so many people want to “boost their immune system;” a boosted immune system is the definition of an autoimmune disease, where your body’s defenses attack its own healthy tissue. Boosting your immune system and reducing your cortisol are not wise aspirations.
I’m always curious about the histories behind false claims and false marketing messages, and the cultural context in which they arise. I know I mention Google Trends all the time, but I really do find it to be a useful tool. It shows the popularity of search terms over time, and it gives us a really interesting snapshot of almost any topic’s cultural popularity at any given time. When we plug in “cortisol belly” we see that nobody had really ever stuck those two words together until the latter half of 2022, when it began an upward surge. It reached its all-time peak in July 2026, just about two months before the date of this episode. Where it might go in the future we don’t know; will it continue climbing as marketers continue the sales pitch? My guess is that’s pretty likely.
We see a little bit of a different picture when we search for just the term cortisol by itself. We see the same growth spurt over the past few years as public interest in cortisol has surged as a result of advertisements for supplements and other products promising to reduce your body fat; but stripped of its marketing partner word belly, the word cortisol by itself has always had a certain modest level of searches. Cortisol is a real hormone and there will always be legitimate discussion of it. But unlike the term cortisol belly, cortisol by itself has a second peak — way back at the very beginning of Google’s data, which they began tracking in 2004. We see the search popularity coming down from a peak that appears to be right around the start of Google’s database. What could that have been?
It turns out that these past few years have not been the only time in which charlatans have tried to make cortisol into a boogeyman, and frighten you into buying products to protect you from its evils. Throughout the mid-2000s, the Federal Trade Commission nailed a whole bunch of companies selling a range of various worthless weight loss supplements during 2003, 2004, and 2005. In late 2005 they announced a settlement with three defendants who would surrender $4.5 million in cash, an investment partnership, vehicles, and real estate. They had been selling the supplement products CortiSlim and CortiStress with “false or unsubstantiated product claims and used deceptively formatted infomercials in pitching the dietary supplements.”
Then in 2007, settlements with four more defendants were announced, who surrendered a further $12 million for making “false and unsubstantiated claims that their products can cause weight loss and reduce the risk of, or prevent, serious health conditions.”
CortiSlim and CortiStress were essentially the same thing as what wellness influencers try to push on the public today — vitamins and/or herbal supplements that had no impact at all on either cortisol levels or weight. CortiSlim was vitamin C, calcium, chromium, magnolia bark extract, beta-sitosterol, theanine, green tea extract, bitter orange peel extract, banaba leaf extract, and vanadium. It falsely claimed that 15 years of scientific research showed that it caused rapid, substantial, and permanent weight loss in all users!
CortiStress was sold as a companion product. Although it contained most of the same ingredients, it promised not weight loss, but protection against diseases normally attributed to chronic stress. CortiStress promised to reduce the risk of — or prevent — osteoporosis, obesity, diabetes, Alzheimer's disease, cancer, and cardiovascular disease.
As we so often observe here on Skeptoid, products that claim to treat everything usually treat nothing.
All of these old products, and the countless new ones today, tend to draw a line from too much stress equals too much cortisol equals too much fat; and reducing your stress results in less cortisol and less fat. As we’ve discussed, any truth there might be in any one of these tenuous links is grossly oversimplified in these marketing messages to the point of being outright false.
So let us conclude by addressing each of the points in this basic pitch:
- Reduce your stress. Yes, we all benefit from lower stress. Chronic high stress causes actual physical conditions like high blood pressure. It causes actual psychological conditions like anxiety and depression. It also causes uncomfortable effects like digestive issues. Untreated, stress can lead to serious life-threatening diseases. Without a doubt, we all want to reduce our stress.
How can we best do that? While acute cases can be addressed with drugs, few among us need that thermonuclear option. Research is clear that everyday calming activities like going for a walk, taking a rest, watching a favorite TV show or movie, hugging your dog, or enjoying a favorite food or drink will do the job. You do not ever need to buy anything; it will not work as well as these simple, proven remedies.
- Reduce your cortisol. Why? First of all, there isn’t really anything you can do to accomplish this; your body is going to continue to produce as much as it requires. No otherwise healthy person has any reason to try to do this. Your cortisol is serving several important functions and it’s not making you fat. Leave it alone.
- Lose weight. There’s no doubt that being overweight leads to many negative outcomes, both physical and psychological. Achieving and keeping a healthy body weight is one of the best things anyone can do to improve their physical health, their energy, their acuity, and their positive body image. It’s also extremely difficult and has no magic bullet. You need to eat less and exercise more, both of which are hard to maintain for the majority of people for whom that’s just not their lifestyle. Even the latest pharma products, the GLP-1 receptor agonists, stop working once you stop taking them, have uncomfortable side effects; and as effective as they are, they will never be as effective as a fundamentally healthy lifestyle. Worthless supplements sold by unqualified online wellness influencers are certainly not the solution.
My overall cortisol-related recommendation is to stop worrying about it, and stop even thinking about it. You can’t control your cortisol levels with random wellness products, and you shouldn’t try. If the problem you actually want to solve is stress or weight, then address those directly. Leave your cortisol out of it.
