in-laboratory study phases, each lasting three weeks in total.
In one phase, two weeks involved significant daily sleep restriction, meaning nighttime sleep of just four hours. The other phase involved no sleep restriction.
Throughout each phase, “we monitored all the food they had,” Somers shares. “But they could eat or order anything they wanted.”
The team found that protein intake rose by 13% and fat intake went up by 17% during the sleep restriction phase, while activity levels remained more or less constant.
Still, “the interesting thing is that when sleep restriction occurred, they only gained about a pound in weight over the study time frame, which is not a large increase,” Somers shares.
“But what really surprised us,” he adds, “is that even after sleep restriction was stopped and eating levels fell back [down], visceral fat continued to increase.
“We don’t know why this happened. We also don’t know what this might mean for people who are already obese. Or for people who struggle with insomnia that they can’t control. That will be for future research,” Somers shares.
How to weight gain
“But what we can tell already is that even for healthy people who lose sleep by choice, this is not a switch you can readily turn off once you turn it on,” he says. “And what’s really important to understand here is that catch-up sleep — after sleep loss — will not necessarily bring you back to normal.”
Somers’ advice: “If you are going to be sleep-deprived for a prolonged period you should pay particular attention to how much food you eat and what your food choices are. And be more conscientious about exercising.”
Also, since visceral fat rises even if the scale barely budges, “know that measuring your weight alone is not going to tell you if things are good or bad,” he says.
The thought was seconded by Dr. Harold Bays, medical director and president of the Louisville Metabolic and Atherosclerosis Research Center, and author of an accompanying editorial.
“Abnormal sleep patterns — especially when due to stress — are likely to worsen body fat function, increase visceral or belly fat, and worsen body composition, even without much change in body weight,” Bays adds. But the solution, he suggests, is simple: Get enough sleep.