Cortisol is a steroid hormone produced by the body in response to fasting, eating, exercising, waking up and stress. Fat cells in the abdomen have more cortisol-activating enzymes than the fat under the skin. There is more blood flow and there are more cortisol receptors in abdominal fat.
Time
Cortisol levels are higher in the early morning then taper off toward the evening. It is constantly released when you are under prolonged "fight or flight" conditions such as chronic stress. It is also temporarily released after an exercise session.
Function
Cortisol mobilizes body fat then moves it to another location or delivers it to tissues in need of fuel, such as working muscles. It helps baby fat cells grow into mature fat cells. Cortisol is also an anti-inflammatory hormone which dampens the immune system during stress. Participating in regular aerobic and resistance training exercise as a means of stress reduction lowers your body's production of cortisol.
Significance
Regular exercise training improves your body's ability to respond to daily stress including stress from exercise. If you have been exercise training, you have a lower cortisol response to exercise than an untrained person, according to William McArdle and colleagues, in their book, "Exercise Physiology, Energy, Nutrition & Human Performance." The lower the amount of cortisol you have circulating in your blood, the less you are prone to building up fat in your abdomen.
Considerations
Drink a protein and carbohydrate shake before and immediately after your weight training session. Consume a thinner solution of protein and carbohydrates during your workout. You will experience less muscle damage and a lower cortisol response compared to a carbohydrate only or protein only shake, according to a 2007 study by Jacob Baty and colleagues, published by the National Strength and Conditioning Association. This makes you less prone to abdominal fat storage.
Muscle Tissue
Cortisol prevents amino acids from entering cells, thereby reducing protein synthesis. This decreases your ability to build muscle tissue. Some strength and power athletes take glutamine supplements to reduce the effects of cortisol, enhancing protein synthesis and improving exercise recovery, according to McArdle. The more muscle you have the greater the number of calories you burn, decreasing your risks of obesity.
References
- "Health and Fitness Journal"; Cortisol Connection: Tips on Managing Stress and Weight; Len Kravits Ph.D.; Oct. 2005
- "Exercise Physiology, Energy, Nutrition & Human Performance"; William McArdle, Frank Katch and Victor Katch; 2007
- "Journal of Strength & Conditioning Research"; Effect of Carbohydrate and Protein Supplement on Resistance Performance and Hormonal Response; Jacob Batey; May 2007
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