People who are attempting to lose weight could find that they are hindering their progress by not getting enough sleep.
A recent research project published in the Annals of American Medicine has suggested that the effect of a calorie-reduced diet can be changed by sleep patterns.
In the study, a group of overweight, non-smoking adults were split into two groups.
The first group was given 8.5 hours of night time sleep opportunity, while the second group had just 5.5 hours to sleep at night.
Lowering the amount of sleep decreased the proportion of weight loss as fat by 55 per cent and increased the loss of fat-free body mass by 60 per cent.
Dr Plamen Penev, one of the authors of the study and an assistant professor of medicine at the University of Chicago Medical Centre, commented: "The loss of lean body mass is an unwanted side-effect of all weight loss diets.
"This side effect was increased by sleep reduction in our study."