One analysis of 20 studies including 300,000 people found a 41% increased obesity risk among adults who slept fewer than 7 hours per night.
Another study found short sleep duration to be significantly associated with greater waist circumference, which is an indicator of the accumulation of belly fat
Astudy in the American Journal of Clinical Nutritionfound that when people were starved of sleep, late-night snacking increased, and they were more likely to choose high-carb snacks. In another study done at the University of Chicago, sleep-deprived participants chose snacks with twice as much fat as those who slept at least 8 hours.
Sleep deprivation makes you “metabolically groggy," University of Chicago researchers say. Within just 4 days of insufficient ZZZs, your body’s ability to process insulin -- a hormone needed to change sugar, starches, and other food into energy -- goes awry. Insulin sensitivity, the researchers found, dropped by more than 30%.
Here’s why that’s bad: When your body doesn't respond properly to insulin, your body has trouble processing fats from your bloodstream, so it ends up storing them as fat.