it can never hurt to exercise a bit. much like everyone here, i grub the hell out when i'm stoned, but i don't gain any weight. infact, i lost seven pounds in two days from not smoking - i'm not sure if that's healthy or not, but whatever. i'm sure if i had an unlimited supply of weed i'd be a fat-ass...unfortunately, i don't.

cardio is your best choice. have a good time, man.