When I started with Zyprexa I was rather underweight and I gained 30 kg (which made me a bit overweight). While tapering off and quitting Zyprexa I lost 15 kg of that weight. Now I'm on Clozapine and I have yet to gain it back.

Not sure how helpful this is, as you're not inquiring about clozapine & because you don't usually get put on clozapine if there are still other options left.. but I just wanted to put in my two cents.