Hi welcome to Health care magic forum. As you correctly guess respiridone has many side effects including weight gain. You can stop it with the doctors advise by tapering the dose. He may substitute the tablets with depo injection with 15days interval if possible, other wise some alternative medicine he may suggest.
Besides i advise some non medical procedures for her as yoga
, hearing music, reading books etc.
Avoid giving her sweets, fatty foods , flushy fruits like banana. spices, chillies, junk foods,etc. Give her more of green leafy vegetables, pulses, sprouts, milk, egg, meat, sea foods, fruits, juices, and dry fruits.
Wishing for a speedy recovery and thanks for calling.