Can smoking weed stop you from gaining weight?

Weed & weight. Marijuana increases your metabolism and may help you lose weight if you are otherwise eating healthy and exercising regularly. But it also stimulates appetite and you may feel like eating more. So if you cannot control the munchies and eat a lot of junk foods without exercising, you will gain a lot of weight.
Doubtful. Most often in medicine it would be used to help gain weight. I would not recommend using it at all but especially for this indication!