I think they mean other antipsychotic medicines. There are quite a few that are less likely to have weight gain.
In terms of other forms to help your issue, eating healthy whole foods are important but many supplements can help. I say help, I’m not sure about meds free. Depends on your condition but you can google about supplements for mental illness.
Julie Rucklidge is a good one to look up. Inositol is one that I take, it helps with depression but I don’t seem to find I can get off meds, it just helps.

If your doc means something other than antipsychotics I’d also be interested in knowing