You'll start stuffing yourself silly
Even if you're not conscious of the tendency, you probably start grabbing greasy, sugary food -- and a lot of it -- when you're short on sleep. In fact, the American Heart Association quantified this chow-down to the tune of an extra 549 calories a day in a group of individuals sleeping roughly an hour and 20 minutes less than the group that maintained a normal level of sleep.
The kicker is that even if you're aware that sleep could screw with your eating habits, you may not be able to outsmart your hormones, which are basically responsible for the food fest. Dr. Caroline Apovian, the director of the Nutrition and Weight Management Center at the Boston Medical Center, explains, "When we do not receive sufficient sleep, our ghrelin (hunger) levels are up all day, and our leptin (satiety) levels are low. In addition, sleep interferes with our impulse control. Despite our best efforts to follow a healthy eating plan, the combination of high ghrelin and low impulse control will lead to overeating. Your cortisol (stress) levels will be high the day following a sleepless night as well, which also prompts overeating, especially on sugary and fatty foods."
So yeah, if you let this go on long enough, all those days, weeks, months, and years of extra calorie, fat, and sugar intake don't add up to a happy, healthy body.