Quick answer: Cortisol is a hormone your body needs; it is not the villain. Problems come from levels that stay high for a long time — most clearly in Cushing's syndrome, which the NHS says is most often caused by long-term, high-dose steroid medicines. For everyday stress, "cortisol belly" is a social-media label rather than a diagnosis, and no supplement, drink or routine has been shown to switch cortisol off.

This guide explains what cortisol does, what the research links to long-term stress, which symptoms are worth taking to a GP and why the latest cortisol trends are not a shortcut. It does not diagnose anything or replace advice from a doctor.

What does cortisol actually do?#

Cortisol is made by the adrenal glands. In a threatening situation it helps secure energy: blood sugar rises, stored energy is mobilised and repair processes are put on hold. Reviews describe glucocorticoids such as cortisol as catabolic hormones that release stored fuel, and link long-term exposure to insulin resistance and cardiometabolic disease (Beaupere et al., 2021). In the short term, that is a useful survival response. The concern is when it never switches off.

Can stress make you gain weight around the middle?#

It can contribute, but it is rarely the whole story. Higher cortisol prompts the liver to release more glucose, which the body meets with extra insulin; repeated over months, insulin sensitivity can fall (Yaribeygi et al., 2022). A review of the stress system in obesity links prolonged high cortisol to insulin resistance, more body fat and type 2 diabetes, including more visceral fat around the internal organs (Gianotti et al., 2021).

Much of that evidence comes from very high cortisol, such as Cushing's syndrome or steroid treatment. For everyday stress, the effect usually runs through sleep, eating patterns and recovery as much as through the hormone itself.

What is "cortisol belly"?#

"Cortisol belly" is a social-media term rather than a medical diagnosis. People use it to describe a bloated stomach, or extra weight around the waist, that appears during a stressful spell. What people describe is usually a mix of long-term stress, short sleep, lower insulin sensitivity, different eating habits and not enough recovery rather than a single hormone out of balance (Gianotti et al., 2021; Yaribeygi et al., 2022).

Does high cortisol affect muscle?#

It can. Cortisol is catabolic, and one genetic (Mendelian randomisation) study found that higher cortisol was associated with lower grip strength and lower lean mass, an association seen in women but not men (Katsuhara et al., 2022). That is one study, not proof that stress "burns muscle" overnight. Strength training, enough protein and sleep remain the foundation.

The evidence behind the ingredients commonly sold as cortisol supplements is modest:

Ingredient or trend What the evidence shows
Magnesium A systematic review found low-quality evidence, only in groups already prone to anxiety; no study measured stress with a validated scale (Boyle et al., 2017).
Ashwagandha A meta-analysis of 12 small trials found lower perceived stress than placebo, but rated the certainty of the evidence as low (Akhgarjand et al., 2022).
Rhodiola A systematic review of rhodiola for fatigue (not stress) called the research contradictory, with every trial at high or unclear risk of bias (Ishaque et al., 2012).
"Cortisol flush" diets and "cortisol release" exercises None of the research cited in this guide tests them. Treat them as social-media labels, not treatments.

If you take medicines or have a health condition, check any supplement with a pharmacist or GP first.

What actually helps with stress?#

The NHS tips to reduce stress are unglamorous and free: be active, take control of what you can, connect with people, make some time for yourself and avoid unhealthy habits. A useful first step is an honest inventory:

  • How is your sleep, and are your sleep times regular?
  • Do you go without proper meals during the day, then eat heavily late in the evening?
  • Does training give you energy, or leave you more tired?
  • Do you get daylight most days?
  • Is there time when nobody needs anything from you?

Planning the week's meals in advance can remove one daily decision on busy evenings.

When should you see a GP?#

See a GP if you notice possible signs of Cushing's syndrome, particularly if you take steroid medicines. The NHS lists more fat on the neck, upper back, chest and tummy with thinner arms and legs, a red round face, easy bruising and stretch marks, muscle weakness at the top of the arms and legs, low sex drive, mood changes, irregular or stopped periods and excess hair growth.

It is also worth getting checked for persistent tiredness, weight gain you cannot explain, a marked fall in exercise capacity, or high blood pressure together with weight gain around the middle. Blood tests and a medical assessment can rule out other causes, such as thyroid problems.

Sources and further reading

About the author

Alexander Eriksson

Founder, Smaklig

Alexander Eriksson is the founder and CEO of Smaklig. He founded Smaklig in 2026 and has worked with data-driven optimisation since 1998. He is the named author responsible for Smaklig’s UK meal-planning guides. His editorial work explains the assumptions behind example meals, shopping quantities and retailer information so readers can check what a guide covers before using it. The UK guides link to official sources for food and health information and distinguish general guidance from illustrative meal-planning examples. Alexander’s byline identifies editorial responsibility. It does not represent a medical, dietetic or food-safety qualification, a clinical review, or personal testing of every UK supermarket service. The guides provide general information and do not offer individual medical or nutrition advice.