If you're struggling to lose weight, scientists say you might want to assess your sleeping habits.
Researchers from the Eastern Ontario Research Institute and Laval University in Canada say a good night's sleep could be just as important as diet and exercise.
They say seven hours' shut-eye is the minimum adults should be getting if they want to improve their odds of losing weight on a diet.
Recent research found lack of sleep prompts hormones in our brains to increase our appetite and make us eat more.
Now the Canadian scientists are calling for medical practitioners to address people's sleep habits alongside their diet and exercise levels.
"The solution to weight loss is not as simple as 'eat less, move more, sleep more,'" Dr Jean-Phillippe Chaput and Dr Angelo Tremblay wrote in the Canadian Medical Association Journal.
"However, an accumulating body of evidence suggests that sleeping habits should not be overlooked when prescribing a weight-reduction program to a patient with obesity. Sleep should be included as part of the lifestyle package that traditionally has focused on diet and physical activity."
One experiment found people who changed their sleep habits from six hours to between seven and eight hours put on 2.4kg less after six years.
Another study got one group of people to sleep for five hours a night and another to sleep for eight-and-a-half hours a night for two weeks while consuming a low fat diet.
The researchers found those with less sleep burnt muscle and stored their fat, while those who clocked eight hours' sleep lost 55 percent more body fat and 60 percent more muscle over the fortnight.