By Marygrace Taylor
Skimp on sleep and your belly may bulge: Not getting enough shuteye can actually mess with your metabolism, new research in the journal Obesity found.
After logging just four hours of sleep a night for five straight nights, people’s resting metabolic rates—the number of calories your body burns while you’re at rest—slowed down by nearly 3 percent.
That equates to burning 42 fewer calories, or the equivalent of a miniature Snickers.
The reason why isn’t totally clear, but researchers think it could have to do with homeostasis—basically, your body’s mission to keep everything in balance.
Since you’re awake longer the day of your short sleep, your body compensates by burning fewer calories the following day, says lead study author Andrea Spaeth, Ph.D., a postdoctoral fellow at the University of Pennsylvania’s Perelman School of Medicine
The result is you’re likely to consume more calories than you need, due to the combination of your slowed metabolism and the increased temptation to eat junk when you’re sleepy.
In fact, one of Spaeth’s earlier studies found that people scarf down as many as 500 more calories following nights when they didn’t get enough sleep, possibly because sleep deprivation revs up hormones that make you feel hungry and dulls hormones that make you feel full.
“Overall, you’re in a positive energy balance, which leads to weight gain over time,” Spaeth says.
The good news, though, is that the effects of your crappy sleep habits can be reversed pretty quickly. After just one 12-hour recovery snooze session, the people in Spaeth’s study returned to their normal metabolisms.