weed speeds up your metabolism, but doesnt neccesarily burn fat or calories. the smoke will burn a few calories but its the thc that speeds the metabolism rate, why do u think they give weed to cancer patients. i dont know about u ppl, but i have been smokin weed for 5 years and im skinny, and pretty much every STONER i know is skinny, coincidence, who knows. Ive seen commercials on tv that say some 2,000 calories get burned for every joints worth of smoking, but thats most likely false information, certain variables must be present for that to be so. such as the quality of the weed, amount you inhale, and the abundance of smoke. smoke in general will burn calories, but THC will speed up the metabolism rate, thus making u hungry. I feel that the rate of metabolism overpowers the munchies, so u dont really gain weight from eating in abundance. if you want to gain wait, weight lift, and excercise, its healthy for you, and you wont be a weak stick of bones.