You want to lose weight the right way in long term? That means not cheating out of it by taking drugs or medications. Especially marijuana, it might screw up your whole mentality. Have you been reading any of the scientific studies on marijuana? Well, you'll see that there's not much point in marijuana. You don't want to suffer the possible effects of it after you're done with it.
Lose weight healthily by:
-Running whenever you have time at a stable pace.
-Cutting down the calories and junk food.
-Exercise more (aerobic) (Wiifit? Biking? Swimming? Hitting the gym?)
-Eat healthy foods!
Stay legal, and stay true. Don't do marijuana, and do things the right way. Have fun with biking! That's good exercise, and hey, that'll burn quite some calories if you stay with it and not cheat on your diet.