London: Are you dieting to shed those extra kilos? Be sure that you don't skip a full night's sleep as it may halve your fat loss, scientists say.
Researchers at the Chicago University found that dieters who cut back on their sleep failed to shed the amount of fat they should otherwise would have lost by adopting a strict eating practice.
According to the researchers, skipping on sleep boosts the production of a hormone called ghrelin that suppresses physical activity and fat-burning processes in the body while increasing hunger.
Professor Plamen Penev of Chicago University, who led the study, said: "If your goal is to lose fat, skipping sleep is like poking sticks in your bicycle wheels."
"Cutting back on sleep, a behaviour that is ubiquitous in modern society, appears to compromise efforts to lose fat through dieting. In our study it reduced fat loss by 55 per cent," Professor Penev was quoted as saying by the Telegraph.
For their study, Penev and colleagues recruited 10 overweight but healthy volunteers for four weeks. For the first fortnight they were allowed to sleep for up to 8.5 hours, and for the second two weeks for up to 5.5 hours.
In the event they slept on average for seven hours 24 minutes in the first part and five hours and 14 minutes in the second.
They found that while both groups lost about 6.5 pounds (3kg) over the course of the experiment, the well-rested group lost more weight from fat than the sleep deprived group.
Detailing their findings in the journal Annals of Internal Medicine, the researchers said that higher levels of ghrelin have been shown to "reduce energy expenditure, stimulate hunger and food intake, promote retention of fat, and increase hepatic glucose production to support the availability of fuel to glucose dependent tissues".
“In our experiment, sleep retention was accompanied by a similar pattern of increased hunger and ... reduced oxidation of fat," they wrote.
During the study, the volunteers were placed on a strict diet of about 1,450 calories a day, or about 90 per cent of the amount needed to maintain a steady weight.
The academics predicted that had the dieters had access to extra food in the study - and so been able to act on their sharper hunger pangs during the sleep-restricted period - the differences in fat loss would have been even greater.
Professor Penev concluded that people "should not ignore the way they sleep when going on a diet".
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