London - Forget arduous gym sessions and endless calorie counting.
There may be a much more relaxing way to slim, research suggests - grabbing some extra shut-eye.
A “sleep diet” could be the best solution if you have a genetic tendency to pile on the pounds, scientists claim.
Sleeping for fewer than seven hours a night appears to “encourage” the genes that cause weight gain, while getting more than nine hours suppresses them, they concluded.
They made the discovery in a study of more than 1,000 pairs of twins, both identical and non-identical.
Only identical twins share exactly the same genes, so the differences between them allowed scientists to establish whether weight gain was inherited or due to environmental factors. For those who slept for fewer than seven hours a night, 70 percent of differences in weight were down to genes, the study showed.
But for those who averaged more than nine hours of sleep, only 32 percent of the variations were genetic.
Dr Nathaniel Watson, who led the US study, said: “The results suggest that shorter sleep provides a more permissive environment for the expression of obesity related genes.
“Or it may be that extended sleep is protective by suppressing expression of obesity genes.”
The findings have been published in the journal Sleep. In their paper, the scientists from the University of Washington suggested that a lack of sleep in hectic modern lifestyles may contribute to obesity. They said the average amount of sleep we get each night has fallen by an hour and a half over the past century.
They wrote: “Modern society with its ubiquitous technology often can cause misalignment between sleep need and sleep actualisation. Evidence is mounting that chronically reduced sleep times are associated with obesity.”
Lack of sleep may influence weight by affecting hormones and metabolism, they said.
Last year scientists at the University of Warwick reported that a lack of sleep could cause high blood pressure in women, but did not affect men.
Women who slept for five hours or fewer were twice as likely to have high blood pressure than those who slept for seven. - Daily Mail