Weight gain isn't associated with all antipsychotics. In fact, abilify, rexulti, latuda, ect... have a low risk of weight gain. Sedation is common, but I have not experienced it on rexulti.

Other medicines would depend on what condition you're trying to treat. If it is a bipolar type disorder then there are mood stabilizers or a depressive type then there are atypical antidepressants like Wellbutrin.