It is important to compare the dynamics of weight gain between short-term and long-term studies. Unfortunately, both short-term and long-term data are available only for some antipsychotics, and this narrowed our comparison (Table 2). In our short-term, retrospective EOS study, adolescents gained an average of 3.6 kg on risperidone, 4.4 kg on olanzapine, and 2.1 kg on clozapine during a 6-week treatment period.25 These results are very similar to those described in a 6-week, open-label study by Fleischhaker et al who reported an average weight gain of 2.8 kg for risperidone, 4.6 kg for olanzapine, and 2.5 kg for clozapine.24 Weight gain reported from other 6-week studies include: