Weight gain induced by haloperidol, risperidon... [Schizophr Res. 2008] - PubMed - NCBI

So here is a study on haldol, risperidone and zyprexa---these are people receiving initial meds so what happens is people on haldol gain maybe a little less the first 3 months but by the end of a year people on all three meds have gained 20 pounds. So I have seen meta-analysis of haldol suggesting lower weight gain but haldol is not a first line treatment and according to my pdoc you pretty much gain all the weight you're going to in the first year then its stable after that so trials where people have already been on APs for a year really aren't valid for this kind of comparison IMO.