Update date: 2010/10/05 15:14 (Reuters New York, 4th)

According to a small U.S. study, people who are trying to lose weight may find it harder to shed body fat if they don't get enough sleep.

The study, published in the "Annals of Internal Medicine," adds evidence to the close relationship between sleep habits and weight control. It also suggests that people on a weight loss plan might want to ensure they get enough sleep each night.

Ten overweight men and women participated in the study, each spending two separate two-week periods living in a sleep laboratory.

During both periods, the participants followed a calorie-restricted diet. In one period, they slept 8.5 hours each night, while in the other, they slept only 5.5 hours.

Researchers from the University of Chicago found that participants lost roughly the same amount of weight—an average of under 7 pounds—during both periods. However, during the sleep-restricted period, they primarily lost muscle rather than body fat.

When participants slept 8.5 hours, more than half of the weight they lost was body fat.

But when they slept only 5.5 hours, only a quarter of the weight lost was fat. Most of the weight loss came from lean tissue, such as muscle.

However, the study has some limitations. Besides its small scale, it only observed short-term weight loss. Central News Agency (Translation)

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