Getting too little sleep might prevent dieters from losing body fat, according to a small US 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.
"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. Penev said it was also unclear how well these findings from a tightly controlled sleep-lab setting might fit the "real world." A number of studies have found self-described "short sleepers" -- typically defined as those who get less than 6 hours of sleep each night -- tend to weigh more or gain more weight over time than people who get more sleep. Lab studies have suggested sleep loss may alter people`s levels of the "hunger hormones" leptin and ghrelin. Leptin is secreted by fat cells; low blood levels of the hormone promote hunger, while increases tell the brain that body is full and encourage calorie burning. Ghrelin is secreted by the stomach to boost appetite. Penev`s study found that under sleep-restricted condition, participants reported greater hunger during the day compared with the 8-hour sleep condition even though they consumed the same number of calories during both periods. They also had higher blood levels of acylated ghrelin, one form of the appetite-boosting hormone. Penev said there wsa no one-size-fits-all prescription for sleep and more studies are needed in real-world settings.Bureau Report
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