On TikTok, cortisol has become the perfect culprit. A slightly round face, a belly that will not shift, an afternoon slump, and the verdict lands, "high cortisol". Then come the morning routines and the capsules meant to bring it down. Cortisol does play a part in belly fat. What really makes it rise is far more ordinary than these videos suggest.
A useful hormone, not a poison
Cortisol, the stress hormone, raises blood sugar to prepare the body to react. It follows a rhythm. It rises in the morning, when it is time to get up and act, then falls in the evening to make way for sleep. Getting out into natural light within an hour of waking helps keep this clock on time.
The trouble starts when it stays high for too long. Chronic stress shows up in the body as a very real biological state. Cortisol that never comes back down weakens the junctions between the cells of the gut and fuels inflammation. Cravings for sugar, fat or alcohol then take over.
A link with belly fat, but a modest one
In the United States, researchers put 59 premenopausal women through laboratory stress tests over four days. Those whose fat sat mainly around the belly secreted more cortisol during the first test. The slimmest of them did not get used to it, and kept secreting more on the following days, even when the tests were already familiar (Epel et al., 2000).
In England, a study measured cortisol in hair, which reflects several months of exposure, in 2,527 men and women aged 54 to 87. The higher it was, the higher their weight, BMI and waist size, and the more likely their obesity was to persist over four years (Jackson et al., 2017).
These two studies show a link, not a cause. In the second, the correlation is weak, around 0.1 on a scale that goes up to 1. Cortisol explains only a small part of the differences in waist size from one person to the next. The rest comes from your plate, movement, sleep, age and other hormones.
The midlife belly is not a cortisol belly
For women, the clearest example is menopause. Before the transition, visceral fat, the fat around the organs, makes up about 8% of total fat mass. Afterwards, it reaches 23% on average, with no change in diet or activity. During perimenopause, the body also becomes less sensitive to insulin, and sugar is stored more easily around the belly.
Baseline cortisol is higher at this stage, that is true. But it is one part of a whole. Reducing everything to a single hormone means missing what really matters. I go through it in my guide Your Body Through Menopause and Beyond.
What really makes cortisol rise
In my guides, I always name the same causes. Short nights, overly strict diets and long, draining sessions. The studies find them.
In Chicago, young men deprived of part or all of a night's sleep had cortisol 37% and 45% higher the following evening, at the time it should be falling (Leproult et al., 1997).
In California, 121 women were randomly assigned to four groups for three weeks. Those eating 1,200 kcal a day saw their total cortisol output rise. And simply tracking calories increased perceived stress (Tomiyama et al., 2010).
Exercise tells another story. In the United States, twelve moderately trained men did 30 minutes of exercise at three different intensities. At low intensity, cortisol did not rise. At moderate intensity, it climbed by about 40%, and by 83% at high intensity (Hill et al., 2008). A rise during exercise is normal, and it comes back down afterwards. The problem is the hour of moderate cardio repeated day after day, especially with too little food. It is too gentle to push the body to adapt, but hard enough to raise cortisol. In perimenopausal women, fasted training raises it too.
What about anti-cortisol supplements?
Ashwagandha, rhodiola, special adrenal capsules. None of my guides recommends them, and I do not recommend any. A capsule does not lengthen a five-hour night, replace a skipped meal or cancel out three sessions too many in a week.
If you think you have a real hormonal problem, talk to your doctor, who can check it. Cortisol cannot be read on a face or a belly.
What brings it back down
Seven to nine hours of sleep, at regular times, even at weekends. Natural light in the morning, little light in the evening. A moderate deficit, around 10% of your needs, rather than drastic restriction. Walking almost every day, and short, intense efforts rather than long sessions that leave you drained.
Add moments of calm throughout the day. A few minutes of slow breathing, with the out-breath longer than the in-breath, a walk without your phone, time with people close to you. The more often these moments come back, the more your body leaves alert mode.
I work with nearly 300 women a year. Those who sleep better, eat enough and stop draining themselves with cardio often see the belly respond before they have touched a supplement. Your body knows how to repair itself. It just needs the chance.
This article is for information only and does not replace medical advice.