The lack of sleep predisposes you to weight gain and obesity by ...
1. changing the way you metabolize carbs and glucose
2. Increase your appetite
3. Lower your metabolism.
Poor glucose metabolism will increase hunger through impaired insulin signaling. Impaired insulin signaling turn, drives hunger. Thus, the mechanism of weight gain, sleep deprivation seems to be impaired glucose metabolism.
In summary, the sleep deprivation-regulates hormones that control the appetite and insulin sensitivity.
Rule of Thumb: sleep deprivation results in impaired glucose metabolism. you can combat this by increasing the main types of fats and restricting sugar processed.