I know add meds like ritalin and adderal promote weight loss. Not sure about bipolar meds. My appetite has been fluctuating a lot on Lamictal. I used to have a very poor appetite, or at least I couldn't eat very much at one time. Now I seem to go a day without realizing that I haven't eaten, then a day where I can't get enough of this glorious thing called food!
I never really weighed myself much before, but I've started to keep track of it. So far no change.