Dieters can improve their chances of losing weight by ensuring they have a good night's sleep, according to research published yesterday.
An adequate night's sleep not only increases fat loss for a dieter but can help control feelings of hunger, a study has shown. The University of Chicago research, published in the Annals of Internal Medicine, studied people aged 35 to 49 – ranging from overweight to obese – who were placed on a calorie-restricted diet.
The volunteers underwent a fortnight where they spent eight and a half hours in bed a night getting an average of seven hours and 25 minutes of sleep. They then spent another fortnight being given five and a half hours in bed, with an average of five hours and 14 minutes sleep a night.
The study found that the dieters lost the same amount, 6.6lb, or around 3kg, during each 14-day session, if they had a full night's sleep or less. But when they had adequate sleep, more than half of the weight they lost was fat compared with only a quarter when they cut back on sleep.
Adequate sleep also helped control the dieters' hunger, the study showed. Average levels of ghrelin, a hormone that triggers hunger and reduces energy expenditure, did not change when the subjects spent eight and a half hours in bed. When they spent five and a half hours in bed, ghrelin levels in the dieters rose over the two weeks.
The volunteers followed a balanced diet, with their calorie intake restricted to 90 per cent of what each person needed to maintain his or her weight without exercise. The number of calories they consumed over both fortnights – about 1,450 per day – stayed the same. They spent their waking hours engaged in home or office-like work or leisure activities.
Plamen Penev, study director at the University of Chicago, 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."
The researchers also suggested that the tightly-controlled circumstances of the study may have masked some of sleep's benefits for dieters as the study subjects did not have access to extra calories.
Dr Penev said this may have helped them to stick with their lower calorie meal plans despite increased hunger. He added: "Obtaining adequate sleep may enhance the beneficial effects of a diet. Not getting enough sleep could defeat the desired effects."
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