A group of volunteers aged 35 to 49 ranging from overweight to obese were all placed on a calorie restricted diet. For a period of two weeks the volunteers spent eight and a half hours in bed each night getting an average of seven hours and 25 minutes of sleep. They then spent the next fortnight being given five and a half hours in bed with an average of five hours and 14 minutes of sleep per night.
The results showed that the dieters lost the same 6.6Ib during each 14 day session irrespective of if they had a full night’s sleep or less. However, when they had adequate sleep, more than half of the weight they lost was fat with only a quarter when they cut back on sleep.
Adequate sleep also seemed to help with controlling the dieters’ hunger, with average levels of the hunger hormone ghrelin staying the same when spending eight and a half hours in bed and rising when spending five and a half hours in bed.
Study leader Plamen Penev has 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.”
He went on to say ”Obtaining adequate sleep may enhance the beneficial effects of a diet. Not getting enough sleep could defeat the desired effects.”