Do You Eat Enough? The Role of Cortisol and it’s Detrimental Effects
Undereating can trigger a cascade of hormonal changes in the body, with cortisol playing a central role. Cortisol, often called the "stress hormone," is released by the adrenal glands to help the body adapt to periods of stress, including inadequate calorie intake. While this response is meant to keep you alive during food scarcity, chronic undereating and elevated cortisol levels can lead to numerous negative effects on the body.
Muscle Breakdown and Gluconeogenesis
Cortisol promotes gluconeogenesis, a process where the liver produces glucose from non-carbohydrate sources, like amino acids. When dietary carbohydrates are insufficient, your body breaks down muscle tissue to supply these amino acids, leading to muscle loss over time. This compromises strength and performance, particularly for athletes or active individuals.
Fat Storage and Metabolic Slowdown
Ironically, chronic cortisol elevation can encourage fat storage, particularly in the abdominal area, as the body prepares for prolonged energy deficits. High cortisol levels can also suppress thyroid function, slowing metabolism and making it harder to lose weight despite eating less.
Impaired Immune and Cognitive Function
Elevated cortisol weakens the immune system, making you more prone to infections and slower to recover from illness or injury. It can also affect brain function, leading to mood swings, anxiety, and difficulty concentrating.
Increased Cravings and Bone Health Risks
Cortisol often increases cravings for calorie-dense, sugary foods, which can derail healthy eating goals. Additionally, it impairs calcium absorption and bone formation, increasing the risk of osteoporosis.
To avoid these adverse effects, ensure you consume enough calories to meet your energy needs, especially if you’re physically active. A balanced diet with adequate protein, fats, and carbohydrates can help regulate cortisol and support overall health.
How to Determine the Right Amount to Eat
Finding the correct amount to eat starts with understanding your body's energy needs, which depend on factors like body weight, activity level, and fitness goals. A straightforward approach is to calculate your macronutrient needs:
Protein Intake: Aim for approximately 1 gram of protein per pound of body weight. For example, a 150-pound individual should consume about 150 grams of protein daily. Protein supports muscle repair and maintenance, especially during periods of training.
Carbohydrate Intake: Carbohydrate needs vary based on activity level. Use a range of 1-5 grams per kilogram of body weight:
Sedentary or low activity: 1-2 g/kg.
Moderate activity: 3-4 g/kg.
High-intensity training: 4-5 g/kg. For example, a 70 kg (154-pound) individual doing moderate training would require about 210-280 grams of carbohydrates daily.
Fats: Allocate the remaining calories to healthy fats. While there’s no one-size-fits-all formula, 20-35% of total daily calories from fat is a good guideline.
Calculating Your Total Calories
To find your total caloric needs you’ll need a resting metabolic test, or you can estimate your basal metabolic rate (BMR) using an online calculator or a formula like the Harris-Benedict Equation, and multiply it by your activity level (sedentary, active, etc.). Then distribute those calories into macronutrients based on the guidelines above.
By tailoring your diet to your unique needs, you can fuel your body effectively, support performance, and avoid the negative effects of under-eating.
Eat well!
Sources:
Cahill, G. F. (2006). Fuel metabolism in starvation. Annual Review of Nutrition.
McEwen, B. S. (2007). Physiology and neurobiology of stress and adaptation: Central role of the brain. Physiological Reviews.
Straub, R. H. (2017). Interaction of the endocrine system with inflammation: A function of energy and volume regulation. Arthritis Research & Therapy.