Eat some healthier food. Try to prepare for the munch session BEFORE you smoke - and put the crisps, chocolate and fatty food in a room that you KNOW you wont be arsed to go to when baked.
At the moment, Im really loving them juicy fruits - you know, the kind where you bite into it and all the juice dribbles down yer chin. Or, you could always get stoned down the park, then when the munchies hit ya go down to the chippy or something. At least youll be doing some sort of exercise to burn off some of the calories.