Cortisol and nutrition

Cortisol and Nutrition is a hormonal and metabolic mechanism whereby the effects of the steroid hormone cortisol on the body are modulated through diet, using macronutrients and micronutrients to manage stress and recovery.

For broad context, see the complete guide to proper nutrition — a foundational guide from the expert team at Sport Zona.

What it is

Cortisol is a glucocorticoid steroid hormone synthesized in the adrenal cortex under the control of the hypothalamic-pituitary-adrenal axis. It is involved in the body's physiological response to stress, whether physical, psychological, or metabolic. Cortisol levels follow a circadian rhythm, being highest in the morning and gradually decreasing throughout the day.

Cortisol's functions are numerous and include regulating carbohydrate, fat, and protein metabolism, modulating the inflammatory response, and maintaining blood pressure. It plays a vital role in providing energy during stress by mobilizing glucose from stores and stimulating its production. In the context of physical activity, cortisol is an integral part of adaptation to training load, but chronically elevated levels can have adverse consequences.

The relationship between cortisol and nutrition is bidirectional – diet can affect cortisol production and metabolism, while cortisol itself significantly impacts metabolic processes related to nutrient absorption and utilization.

How it works

When the body is under stress, whether from intense training, lack of sleep, or psychological tension, the hypothalamus releases corticotropin-releasing hormone (CRH), which stimulates the pituitary gland to produce adrenocorticotropic hormone (ACTH). ACTH, in turn, signals the adrenal glands to release cortisol. Cortisol acts on multiple tissues to provide energy, such as stimulating protein breakdown (catabolism) in muscles to obtain amino acids, which can then be converted into glucose in the liver (gluconeogenesis).

Nutrition can modulate this response in several ways. Adequate carbohydrate intake before, during, and after training can reduce cortisol secretion, as it provides a readily available energy source, thus reducing the need for cortisol-induced gluconeogenesis. Protein is essential for muscle repair and can mitigate the catabolic effects of cortisol. Certain micronutrients, such as magnesium and B vitamins, also play a role in regulating the stress response and supporting adrenal gland function. Chronic calorie deficit or an unbalanced diet can chronically elevate cortisol levels, worsening recovery and compromising athletic performance.

Why it's important for athletes

For athletes, managing cortisol levels through nutrition is critical for optimizing recovery, preventing overtraining, and maintaining anabolic processes. Intense training inevitably leads to increased cortisol, which is a normal adaptive response. A problem arises when this increase is chronic and not adequately compensated for through recovery and nutrition, which can lead to overtraining, muscle loss, reduced immune function, and a decline in overall health.

Carbohydrate intake, especially around training, is key. According to the International Society of Sports Nutrition (ISSN), consuming 1.0-1.2 grams of carbohydrates per kilogram of body weight per hour in the first 4 hours after training can significantly improve glycogen replenishment and reduce catabolic effects. Adequate protein intake (1.6-2.2 grams per kilogram of body weight daily for active individuals) is also vital for minimizing cortisol-stimulated muscle protein breakdown. Maintaining a healthy energy balance, where energy intake matches energy expenditure, prevents metabolic stress that can also elevate cortisol. Deviations from these recommendations can compromise training adaptation and reduce athletic performance.

Related concepts

• Gluconeogenesis — Cortisol stimulates gluconeogenesis, a process where the liver produces glucose from non-carbohydrate sources to provide energy during stress.
• Catabolism — Cortisol is a potent catabolic hormone that breaks down muscle proteins and fat stores to provide energy, which is particularly important in the context of training and recovery.
• Energy Balance — A negative energy balance (calorie deficit) can increase cortisol levels as the body mobilizes energy stores, highlighting the importance of nutrition.
• Anabolism — Cortisol acts counter to anabolic processes (like building muscle tissue), so managing it is key to maintaining a favorable anabolic-catabolic ratio.