Cortisol

Cortisol is a glucocorticoid hormone produced by the adrenal cortex, often called the stress hormone. However, it's much more than that - cortisol regulates blood sugar, immune response, inflammatory reactions, and energy mobilization. The normal cortisol rhythm is high in the morning (helping you wake up) and decreases toward evening (preparing for sleep).

Short-term cortisol elevation is necessary and healthy: it helps you perform in stressful situations, enhances training response, and maintains alertness. The problem arises when stress is chronic. Long-term high cortisol levels increase appetite especially for energy-dense foods (sugar, fat), drive emotional eating, disrupt sleep, and promote visceral fat accumulation in the abdominal area. In studies, chronic stress has been linked to 2-5 kg of weight gain per year.

Cortisol also breaks down muscle tissue for energy, which is particularly harmful for someone losing weight - loss of muscle mass lowers metabolism. Additionally, high cortisol causes fluid retention, which shows as weight gain on the scale even though no fat has accumulated. This explains why weight can increase during stressful times even when eating hasn't changed.

Cortisol can be managed with concrete actions: sufficient sleep (7-9 hours) is the most effective single measure, moderate exercise (not overtraining), mindfulness or breathing exercises, spending time in nature, social support, and limiting alcohol. Excessive training raises cortisol further, so the balance between training and recovery is essential. Cortisol is closely related to melatonin, leptin, and stress management concepts.

Last updated: March 30, 2026