You Don't Sleep Enough
Sleep doesn't just recharge your mental and physical batteries; it helps your body maintain proper levels of appetite-regulating hormones. Score too little shuteye, and your system will pump out more ghrelin, a hormone that makes you feel hungry. Meanwhile, levels of leptin, a hormone that promotes feelings of fullness, will take a hit, says Moon. Burning the midnight oil every once in a while probably won't affect your love handles. But consistently not sleeping a good seven or eight hours nightly can, even if you don't feel exhausted.