Weight Loss - Ghrelin and Cortisol Hormones

Sleep Away the Pounds: Optimize Your Sleep and Reset Your Metabolism for Maximum Weight Loss
by Cherie Calbom, John Calbom

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Ghrelin: The Appetite-Stimulating Hormone

In the last few years, research has begun pointing to an array of diet and lifestyle factors (sleep deprivation is one of the primary ones) that modify the body's production of the hormone ghrelin - the appetite-stimulating hormone that gives people the munchies. Researchers have found that a spike in ghrelin after a short night of sleep can lead to indiscriminate and sometimes out-of-control eating patterns. For example, a sleep study conducted by Dr. Van Cauter found that individuals with the biggest hormonal changes craved the most fattening foods, including ice cream, cakes, candy, pasta, bread, and salty snacks such as potato chips. There were no cravings for fruits and vegetables.

Dubbed ghrelin, after a Hindu word for "growth," this twenty-eight-amino-acid peptide reflects a complex interplay of chemical signals that scientists are now beginning to unravel. Ghrelin was discovered as the peptide hormone that potently stimulates the release of growth hormone from the anterior pituitary gland. It was determined that ghrelin, along with several other hormones, has significant appetite-stimulating effects.

Secreted by epithelial cells in the stomach and the upper part of the small intestine, ghrelin acts on the brain. In both rodents and humans, ghrelin increases hunger through its action on the hypothalamic feeding centers. Humans injected with ghrelin reported sensations of intense hunger; in one study, when turned loose at a buffet, they ate 30 percent more food than they would normally.

Ghrelin appears to suppress fat utilization in adipose (fat) tissue. This may explain why dieters who lose weight and then try to keep it off make more ghrelin than they did before dieting. It's as if their bodies are fighting to regain the lost fat, researchers reported in the New England Journal of Medicine. In short, their bodies seem to be trying to hold on to fat stores in case there is another "famine."

The featured players in appetite suppression and ghrelin management include insulin, which is made in the pancreas (a lack of insulin increases a rodent's call to eat), and leptin, manufactured by fat cells. These two hormones turn down the dial on ghrelin production and help control appetite when your diet is high on plenty of refreshing sleep.

Cortisol: The Hormone that Affects Metabolism and Belly Fat

Sleep loss affects the hormones of the hypothalamic-pituitary-adrenal (HPA) axis. In a natural rhythm with the sleep-wake cycle, cortisol, one of these HPA axis hormones, is released at various times throughout the day and night. It is commonly released in response to physical or emotional stress, in effect prolonging the body's fight-or-flight response. When we are deprived of sleep, cortisol is released at an increased level, which makes us feel hungry even if we're full. As a result, people who continue to lose sleep on a regular basis will tend to experience hunger even when they have had an adequate amount of food.

Cortisol also raises blood sugar and insulin levels, which causes an increase in fat deposition, especially on the belly. The increase in blood sugar then stimulates a further increase in insulin, which sets off a whole scenario of problems discussed earlier. In addition, it causes fluid retention, muscle weakness, memory loss, and high blood pressure. It also has detrimental effects on other aspects of our endocrine system, such as thyroid gland function, which governs our metabolism. (A slow metabolism causes us to gain weight.)

According to a study published in the Lancet, sleep deprivation causes an elevation of stress hormone levels in the evening as well as a heightened stress response throughout the day. Normally, levels of cortisol should decrease at night, increase as morning approaches, and peak around the time the sun rises as part of the body's physiological response to awakening, preparing it to face the day alert and energized. Without realizing it, some people are stuck in a hyperalert state all night with cortisol levels high throughout the night; consequently, they sleep lightly or awaken constantly. Others are "off cycle," with cortisol peaking in the night followed by low cortisol levels in the morning. These people often awaken during the night and are unable to return to sleep, sometimes for hours, if at all, and are tired and groggy in the morning and hungry throughout the day.

Oversecretion or a disrupted secretion of cortisol can drastically interfere with slow-wave delta sleep, which occurs primarily when cortisol levels are decreasing. Wakefulness and Stage 1 sleep are associated with increased plasma cortisol concentrations, which are meant to rise only in the morning. When cortisol is out of balance, it can contribute to insomnia and also the tendency to awaken often during the night, and to feel unrefreshed even after getting a full night's sleep.

Adequate and refreshing sleep effectively reduces cortisol. When hormones such as cortisol are balanced and secreted in the proper cycle, we should sleep well all night and awaken refreshed and restored physically, mentally, and emotionally.

Copyright © 2007 by Cherie Calbom and John Calbom

About the Author

Cherie Calbom is known to millions of fans as "The Juice Lady," and her infomercials are world-renowned. A registered nutritionist, Cherie Calbom has become one of America's foremost celebrity experts on "drinking your vitamins." Her previous books, Juicing for High Level Wellness and Vibrant Good Looks (Crown, 1999), and Juice Lady's Guide to Juicing for Life (Avery, 1992).

John Calbom, MA, is director of Trinity Retreat House and vice president of Trinity Wellness Institute. He is a behavioral medicine specialist, organizational development consultant, Eastern Orthodox priest, and coauthor of The Complete Cancer Cleanse.