Cortisol gets described online as the thing standing between you and the body you want. It's actually the hormone that gets you out of bed. It runs on a daily curve, highest in the morning and lowest at night, and it regulates blood sugar, blood pressure, inflammation, and how much energy the body makes available when something demands it. Exercise raises it. That's the point of exercise.

A hard session raises cortisol for a few hours, then it settles. Chronic stress never allows the settling. The body doesn't keep separate accounts for work, caregiving, money, bad sleep, and training. It adds them up, and when the total outruns the capacity to recover, strength stalls and motivation goes, and the natural conclusion is that the program isn't working.

An acute training spike is a different condition than chronically elevated cortisol, and treating them as the same thing is how people end up buying a supplement to solve a sleep problem. "Cortisol belly" turns out to be a product category. Five hours a night turns out to have a price.

Plus: the case for walking into the gym anyway on the worst days.

Links & Notes

On cortisol's normal daily rhythm

• Cortisol Awakening Response: Regulation and Functional Significance — Endocrine Reviews
• The circadian system modulates the cortisol awakening response in humans — Frontiers in Neuroscience

On exercise, cortisol, and stress regulation

• Effects of a 12-week endurance training program on the physiological response to psychosocial stress in men: a randomized controlled trial — Journal of Behavioral Medicine
• The effects of exercise intensity on the cortisol response to a subsequent acute psychosocial stressor

On "cortisol belly"

• The 'cortisol belly' myth: when diet culture is rebranded as wellness — The Conversation
• 9 Myths About the 'Stress Hormone' Cortisol — TIME
• Routine Screening for Cushing's Syndrome Is Not Required in Patients Presenting with Obesity

On sleep

• Sleep loss lowers testosterone in healthy young men — UChicago Medicine (Leproult & Van Cauter, JAMA 2011 — the 10–15% finding)
• Sleep loss boosts hunger and high-calorie food choices — University of Chicago
• Impact of Five Nights of Sleep Restriction on Glucose Metabolism, Leptin and Testosterone in Young Adult Men — PLOS One

On energy availability and reproductive hormones

• Hypogonadism in Exercising Males: Dysfunction or Adaptive-Regulatory Adjustment?

Show links

• ELEV8 Fitness
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