Feeling peckish? Try getting a little more sleep if you want to eat less, a new study in the European Journal of Clinical Nutrition suggests. In an analysis of 11 sleep studies involving 172 participants, researchers at King’s College London found that people who were allowed only about four hours to sleep in a lab took in an average of 385 more calories the next morning than people who were granted between seven and 12 hours of shut-eye. So basically, people who sleep less eat more. Those extra calories are the equivalent of a cupcake, a serving of French fries, or—if you’re British, apparently—four and a half slices of toast. Researchers also found that sleep-deprived people were more likely to eat more fat and less protein than their well-rested counterparts.
“The main cause of obesity is an imbalance between calorie intake and expenditure and this study adds to accumulating evidence that sleep deprivation could contribute to this imbalance. So there may be some truth in the saying ‘early to bed, early to rise, makes a man healthy and wise,'" said Dr. Gerda Pot, the study’s lead author, in a King’s College of London release.
What’s the explanation? One of the studies the researchers looked at found that sleep deprivation caused people to view food as a reward, resulting in increased motivation to seek it. Another cause may be that reduced sleep causes a disruption of the internal body clock, which impacts the regulation of the hormones that control the feelings of hunger and fullness. Regardless, Pot said, the health affects of insufficient sleep are significant and its link to weight gain specifically needs to be better understood.
“Reduced sleep is one of the most common and potentially modifiable health risks in today’s society in which chronic sleep loss is becoming more common,” Pot said.
There’s more work to be done beyond this analysis to figure out what’s going on, the researchers admit. All of the sleep studies they looked at were in lab settings and only lasted between a day and two weeks. Ideally, they’d like to test people in everyday life and over longer periods of time. Currently, lead author Haya Al Khatib of King’s College London said, researchers are working on a randomized control trial looking at people who regularly don’t get enough sleep.