Betta Blockers and weight gain

I have been on Propranolol (Inderal), a Betta Blocker, for close to 2 years. For an irregular heart beat. I noticed after being on it for about a month that I was gaining weight, even though I have always been very careful to watch my weight. The weight gain continued. If I diet, really hard, the best I can do is not gain any more. Doctors are useless, in my opinion, I mentioned it afew times with no real response. Has this happened to anyone else????? Is there anything I can do about it????