Clozapine's effects on body weight and resting metabolic rate: a case series.

The purpose of this pilot study is to determine if an association exists between clozapine-associated weight gain and resting metabolic rate (RMR). In doing so, we used a "pretest-posttest" single group design in which we measured resting metabolic rate and total body weight prior to implementing clozapine therapy and then again approximately 1 month after initiating clozapine therapy. The results of three patients treated with clozapine revealed an inverse relationship between resting metabolic rate and total body weight. Resting metabolic rates were notably reduced by 10.3-16.0% whereas total body weights had increased between 2.9 and 9 kg. To our knowledge, this is the first documentation of an antipsychotic medication being associated with the reduction in resting metabolic rate.