Some will increase your appetite and the other ones slow your metabolism. Your problem is probably the Effexor.....booooo Effexor. (I take it too.)
Sometimes I find that anti-psychotics make me gain more weight.
You just need to really watch what you eat and get exercise
every day.
Also, don't take Zyprexa. I gained 30 lbs in 4 weeks on that one.