Dieters need a good night's sleep to fight fat: study

Mon Oct 4, 2010 9:06pm EDT
 
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NEW YORK (Reuters Life!) - Getting too little sleep might prevent dieters from losing body fat, according to a small U.S. study.

The study, published in the Annals of Internal Medicine, adds to evidence that sleep habits play a role in weight regulation and suggest people embarking on a weight-loss plan may want to make sure they are catching enough shut-eye each night.

The study included 10 overweight men and women who lived in a sleep lab for two separate two-week periods.

During both periods they followed the same calorie-restricted diet but for one period, the participants slept for 8.5 hours per night, while during the other they got 5.5 hours.

Researchers from the University of Chicago found the dieters lost the same amount of weight under both conditions -- just under 7 pounds, on average. But during the sleep-restricted period, they mainly lost muscle rather than fat.

When participants got 8.5 hours of sleep, more than half of their weight loss came from shedding fat.

But when they got 5.5 hours of sleep, only one-quarter of their weight loss came from fat -- translating to a 55 percent reduction in fat loss. The majority of their weight loss came from lean body tissue, which refers to muscle and any other body tissue that is not fat.

"So they lost the same amount of weight, but the composition was different," said researcher Dr. Plamen Penev, an assistant professor of medicine at the University of Chicago. Penev said successful dieters always shed a certain amount of muscle but wanted to limit that loss in favor of shedding fat.

The study, however, has a number of limitations. Besides its small size, it also looked only at short-term weight loss. More research is needed to see how sleep duration might affect dieters' body composition over time, Penev said.   Continued...

 
<p>Two audience members watch the 2007 "Farm Aid" concert in New York in this September 9, 2007 file photo. REUTERS/Lucas Jackson/Files</p>