When you're short of sleep, it affects your metabolism - your basic life systems have to work harder because they didn't get to rest as long as they wanted, so your body stores more fat to prepare for that mode of functioning. And guess where that fat is stored - belly!

Also, the hormones released for functioning during sleep-deprived days are ones that trigger appetite and, specifically, carb cravings! So in addition to the emotional likelihood that being tired makes it harder to tell yourself the right things and make the hard right choices about eating, your physiology is working against you, too!
I always make sure to go to bed on time, if not early, the night before my weekly weigh-in so that while I sleep, all that muscle building and fat burning can make an extra difference!
