File this research as yet another reason to get more sleep: a commentary, published in the Canadian Medical Association Journal, by two obesity experts has revealed that sleep is just as important as diet and exercise in the fight to lose weight.

"Chronic sleep restriction is pervasive in modern societies, and there is robust evidence supporting the role of reduced sleep as contributing to the current obesity epidemic," Jean-Philippe Chaput, from the Children's Hospital of Eastern Ontario Research Institute in Quebec, Canada and Angelo Tremblay, from Laval University in Quebec, write in their commentary.

The pair studied several studies on obesity and sleep, and conducted two of their own. They found that overtired brains prompt people to eat more and that some hormones that regulate metabolism and appetite are unable to work properly if people have not gotten enough rest.

One study that the experts cited was published in 2010 in the Annals of Internal Medicine. Two groups of overweight adults were put on a diet that forced them to cut 680 calories a day. One group slept five and a half hours a night; the other slept eight and a half hours every night. By the end of two weeks, the group that had slept less had lost 55 percent less body fat than their counterparts, and had lost 60 percent more lean muscle mass. Researchers concluded that, when the body is tired, holding onto fat is a priority.

Chaput and Tremblay also conducted their own study with 123 adults. After 17 weeks, they were able to predict weight loss based on the amount of sleep participants had.

In another, longer study conducted over six years, they found that well-rested adults who slept for seven or eight hours a night gained, on average, 5 fewer pounds than people who slept for six hours a night or fewer.

Experts have predicted that, by 2030, half of the United States' adult population will be obese if trends continue on their current track.

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