Cortisol
The stress hormone made by the adrenal glands, which raises blood glucose and alertness under stress and follows a daily rhythm (higher in the morning).
Cortisol is a glucocorticoid hormone produced by the zona fasciculata of the adrenal glands in response to stress (via the HPA axis: hypothalamus-pituitary-adrenal).
Functions:
- Raises blood sugar (catabolism) to fuel the brain and muscles in case of danger
- Suppresses inflammation (useful in the short term)
- Reduces digestion and immunity (not a priority in acute stress)
- Circadian rhythm: peak around 6 a.m., lowest around midnight
A fresh angle: cortisol is not the enemy. A morning peak is normal and desirable (energy to wake up). The problem is CHRONICALLY high cortisol (persistent stress).
Chronic stress (intense work, lack of sleep, calorie restriction) keeps cortisol high, which:
- Promotes fat storage (especially visceral fat, around the liver)
- Damages the microbiome (via dysbiosis)
- Reduces muscle protein synthesis
- Worsens systemic inflammation
- Disrupts women’s hormonal cycles
Management: there are no magic supplements (adaptogens such as ashwagandha help modestly). The real levers are regular sleep, meditation and relaxation, moderate exercise (intense exercise adds stress) and reducing chronic stress.
A nutrition trap: many people feel guilty about their food choices during chronic stress, when it is the stress that is driving the behaviour. Treat the stress first.