Site Search

Cortisol: How it interfere's with fat loss and what to do about it (Part II)

By Doug Jackson, M.Ed.,CSCS

This article is Part II in a 3-part series about how the stress hormone cortisol affects fat loss in exercisers.

While I don't intend to turn this article into a scientific review of stress, I believe it's important to cover some basics. When we delve into the physiology of the stress response, we find that there are three pathways of long-term stress response: the thyroxine axis, the vasopressin axis and the adrenocorticotropic axis (ACTH axis). The ACTH axis has been focused on most heavily. ACTH stimulates the adrenal glands to release corticoids including cortisol, costicosterone and cortisone.

Cortisol has been studied most extensively. Shawn Talbot, Ph.D., and author of The Cortisol Connection, states, 'Over the long-term, elevated cortisol may be as detrimental to overall health as elevated cholesterol or elevated blood sugar.' High cortisol levels have been linked to a lowered testosterone: cortisol ratio, a prime marker of anabolic status and the ability to recover from exercise and build muscle. Further, as cortisol continues to increase, chances for muscle atrophy, impaired immunity, vitamin depletion and increased blood pressure occur. While so-called 'cortisol blocking' supplements have been largely hype, controlling cortisol is important for people who want to remain in optimum health.

Cortisol and Obesity: As stress heightens, cortisol is released. While cortisol has beneficial effects on the body, the constantly high levels of it are problematic. According to the book Fat Wars, stress increases carbohydrate cravings due to the neurotransmitters NPY and serotonin. Thus, stress-related eating may increase caloric intake and increase body fat.

However, even when caloric increases are considered, cortisol still tends to promote the storage of fat, specifically to the abdominal area where it can quickly be utilized for the fight or flight response. Scientists have found an increased level of activity of the enzyme 11b hydroxysteroid dehydrogenase type 1 (11b HSD-1) in abdominal fat that they believe is the cause of the correlation between cortisol and abdominal fat. A recent study by Roland Rosmond and Per Bjourntorp found that stress-related cortisol secretion in men is strongly associated with abnormalities in glucose, insulin and lipid metabolism as well as abdominal obesity.

Exercise and Cortisol: According to Andrew Fry, Ph.D., many people continue to increase both volume and intensity of exercise as they progress, although the body cannot adapt to this over a long period of time. Fry also states, as intensity of exercise goes up, exercise volume must go down, and vice versa. According to Fry, the testosterone: cortisol ratio, which is a marker of an individual's anabolic status and recover ability, decreases as exercise volume increases.

During intensive strength training, the type of training used to transform bodies, the body enters a catabolic state where there is a net protein breakdown in the body. During this time, ACTH and cortisol are released to decrease muscle inflammation and to begin breaking down amino acids for the process of protein synthesis after exercise. While this is a natural and necessary response, excessive cortisol has been associated with overtraining syndrome.

Nutrition, Cortisol and Recovery Ability: Nutrition has a powerful effect on recover ability. In a day where low-carbohydrate diets are popular, it's important to realize how carbohydrate depletion impacts exercise response and recovery. When examining nutrition and stress response, we must look at a couple of different factors: total caloric balance and exercise nutrition. Cortisol is increased in a linear fashion as we drop below caloric balance. Thus, as people decrease their caloric intake to lose weight, cortisol tends to rise. Cortisol is also increased on low-carbohydrate diets when blood sugar levels drop too low.

During exercise, the body will breakdown an increased amount of muscle proteins as fuel if there is an inadequate supply of carbohydrates. However, it has been found that consuming a carbohydrate beverage during exercise attenuates the rise in cortisol levels and limits the amount of exercise-related immunosuppression.

Lack of Sleep and Cortisol: Current research indicates that sleep deprivation can lead to an elevation in cortisol and is harmful to carbohydrate metabolism; changes which increase the chance of obesity. According to Michael Thorpy, Ph.D., and director of the Sleep Wake Disorders Center at Montefiore Medical Center in New York, "Sleep loss is associated with striking alterations in hormone levels that regulate appetite and may be a contributing factor to obesity. Anyone making a commitment to losing weight should probably consider a parallel commitment to get more sleep."

Now that you have a solid understanding of the science behind stress physiology, cortisol, sleep, and nutrition, in Part Three, I'll put it all together for you, make some conclusions, and give you my recommendations for how to proceed.

About the Author:

Doug Jackson, M.Ed., CSCS, is the author of Fitness Now and Forever and the co-author of Family Fit Plan. He also operates a fitness consulting business in Weston, Florida. To receive his Ten Secrets to your Best Year Ever mini-course, visit www.PersonalFitnessAdvantage.com.