Thursday, November 04, 2010

When Dieting To Lose Weight, How Much You Sleep May Be As Important As How Much You Eat

When Dieting To Lose Weight, How Much You Sleep May Be As Important As How Much You Eat

According to a new study being published in Annals of Internal Medicine, the flagship journal of the American College of Physicians, lack of sleep may hinder a dieter's ability to shed excess body fat.

Ten overweight but otherwise healthy adults on a moderate calorie-restricted diet were randomly assigned to sleep either 5.5 hours or 8.5 hours each night in a closed clinical research environment. After two weeks, researchers measured loss of fat and lean body mass. Compared to participants who slept 5.5 hours a night, the dieters that slept for 8.5 hours lost 56 percent more body fat. The dieters in the sleep restricted group had lost less fat and more lean body mass.

"These results highlight the importance of adequate sleep for maintenance of fat-free body mass when dieting to lose weight," said Plamen Penev, MD, PhD, Assistant Professor, Section of Endocrinology, at the University of Chicago and lead author of the study.

While measuring fat loss was the primary objective of the study, researchers also assessed other factors including levels of hormones that affect the appetite and weight. In addition, participants in both groups were asked to report how much hunger they experienced during the study.

"Among other hormonal effects, we found that sleep restriction caused an increase in ghrelin levels in the blood," said Dr. Penev. "Ghrelin is a hormone that has been shown to reduce energy expenditure, stimulate hunger and food intake, promote retention of fat, and increase glucose production in the body. This could explain why sleep-deprived participants also reported feeling hungrier during the study."

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