Exercise will help ~a little in my experience, to keep you in shape. But the drugs will maybe give you a wolf's appetite that's extremely hard to curb. The often rotten side effects must be accepted if you want their benefits. Your choice. It's not easy to categorize what's wrong, changes take place & maybe you'll change categories? Once diagnosed it's very difficult to change the initial diagnosis, which may have been a swift affair. In the end you'll have to sort yourself out with whatever aid you will accept. Keep exercising, it will maintain your self esteem ~& may even help in other areas. Best wishes.George
You want help but you don't want to accept the help in the form of medication. Supposing you actually have bipolar, then a mood stabilizer is necessary if you actually want help. Not all of them contribute to weight gain. Also, even if a drug is associated with weight gain you can diet and exercise to keep it down.
http://en.wikipedia.org/wiki/Bipolar_disorder