Yeah just because weed speeds up your heart rate doesn't mean you are burning calories. To burn calories you have to atleast spend 20 minutes doing some sort of aerobic exercise. Whether it be sex, jogging, running, jump rope. Something. You may even burn calories at work if you have a very physical job. But Weed slows down everything in your body except your heart rate. And you also eat. So no you don't lose weight from smoking pot. If anything you may gain weight. Doubtful but if you smoke every day all the time and you give into the munchies every time you feel them then I would say you would put on a few pounds. I have found that drinking water when I feel the munchies comming on helps curb my appetite. Water also helps you lose weight. It also tricks your brain if you aren't actually hungry into thinking that your belly is full. Not to mention it helps cotton mouth.