Cortisol, "Adrenal Fatigue" and What the Science Supports

What cortisol is

Cortisol is made by the adrenal glands, two small organs that sit on top of each kidney. They also make aldosterone, adrenaline and noradrenaline. [2] NIDDK calls cortisol "sometimes called the stress hormone" and says it is essential for life. [3] When you feel anxious or scared, your body releases stress hormones such as adrenaline and cortisol, which can speed the heart and cause sweating. [4]

So cortisol is not a "bad" hormone to be minimized. The goal is not to have as little as possible.

"Adrenal fatigue": the claim

According to the Endocrine Society, the idea says long-term stress overwhelms the adrenal glands so they cannot make enough hormone, which then causes symptoms such as tiredness, trouble sleeping or waking, salt and sugar cravings and needing caffeine to get through the day. [1]

1. It is a real medical condition

   The Endocrine Society says no scientific proof exists. [1] A systematic review of 58 studies concluded there is no substantiation that "adrenal fatigue" is an actual medical condition and called it a myth. [5]

2. A saliva or blood test can detect it

   The Endocrine Society says no test can detect it; tests offered are not based on good scientific studies. [1]

3. Special supplements treat it

   The Endocrine Society says these supplements have not been tested for safety, and treatment for adrenal fatigue is not FDA-approved. [1]

The review had limits too: it included a mix of study designs and noted conflicting findings in many studies. [5]

Real adrenal conditions

• Adrenal insufficiency (including Addison's disease): the adrenal glands do not make enough cortisol. Common symptoms are fatigue, muscle weakness, loss of appetite, weight loss and abdominal pain. It is diagnosed with blood tests and treated with medicines that replace the missing hormones. [3] Causes include autoimmune disease or suddenly stopping steroid medicines. [3]
• Cushing's syndrome: too much cortisol. It is rare, and the most common cause is taking high doses of steroid medicine for a long time. Features can include more body fat on the neck, upper back, chest and tummy, a red round face, easy bruising and stretch marks. [6]

Online, "cortisol belly" usually means belly fat blamed on stress. The only cortisol-related fat pattern described in the sources read here is the one in Cushing's syndrome above, which is a medical condition for a doctor to check. These sources do not show that everyday stress alone causes it. Do not suddenly stop steroid medicines on your own: that can itself cause adrenal insufficiency. [3]

Can you "lower cortisol"?

A few small areas of research touch cortisol. Measuring cortisol is a biomarker (a lab number), which is not the same as feeling better or having better health.

1. Slow, deep breathing

   Promising but limited

   NCCIH says studies show it may modestly lower blood pressure and cortisol; a 2019 review of 3 studies (880 people) found preliminary evidence it may reduce stress. [7]

2. Focused-attention meditation

   Promising but limited

   A 2017 review of 8 studies found it reduced blood pressure and cortisol levels. [7]

3. Ashwagandha

   Promising but limited; see stress supplements compared

   A 2024 meta-analysis of 9 randomized trials (558 people) found lower perceived stress, anxiety and serum cortisol than placebo; four trials reported mild to moderate side effects, and long-term safety is not known. [8] NCCIH says liver injury has been rare but reported. [9]

4. Everyday habits

   Established recommendation (general advice)

   Sleep, movement, healthy food and a regular routine will almost always make you feel better, whatever the diagnosis, according to the Endocrine Society. [1]

Proper evidence not found in the sources read here showing that lowering cortisol with a supplement improves health outcomes.