In this article we review the empirical literature on weight gain associated 
with neuroleptic drug use. Weight gain, which appears to be associated with an 
increase in appetite, is variable but likely to be larger initially and then 
plateau. Clozapine and low-potency phenothiazines are associated with the 
largest gains and molindone with weight loss, but the mechanism is not known. 
Amantadine and fenfluramine may reverse weight gain to some degree. Dietary fat 
seems to play an important role in obesity, and research is needed to increase 
the data base and elucidate possible mechanisms. Studies are also needed to 
evaluate preventive strategies and to determine which drugs are least likely to 
produce weight gain as well as which drugs could be added to a neuroleptic 
regimen to control weight.