there are a lot of antipsychotics on the market. almost all of them are associated with at least a bit of weight gain. the higher potency older ones (haldol, prolixin, stelazine) are associated with less weight gain, while some of the newer, 'atypical' drugs, such as zyprexa and clozapine, are associated with -lots- of weight gain. dosage matters, too...there's a big difference between taking 3mgs/haldol daily and taking 20mgs/haldol daily, in all respects...including weight gain.

some doctors use metformin with antipsychotics, to reduce or prevent weight gain. often helps. a switch from, say, zyprexa to abilify or geodon or latuda might help, too. that's assuming an antipsychotic is necessary, long term, for someone. most people who end up with a label of 'schizophrenia' seem to need at least a low dose of antipsychotic, long-term, but something like 20% have a one time episode and can taper off.

one problem is that stimulants are ill advised in schizophrenia, so treatment options for the weight gain are kind of...limited. i've known of -1- person with schizophrenia who was also treated with old school diet pills to combat the weight gain, with OK results. maybe its more common now?