I have this problem as sometimes I have to write at night through the night and it sets off my poor eating habits. I am very, very disciplined in my eating even counting calories daily. Yet when I stay up even one night a week to write through the night, I do have weight gain and it screws up my eating cycle that next day and often days to follow even with a regimented workout schedule. It is critical if one wants to maintain weight or lose it that they sleep atleast 7-8 hours a night if this is what works for their body. (and eat and workout appropriately for body size and need.)