Exercise and Olanzapine-samidorphan

The principal hypothesis is that Olz/Sam combined with aerobic exercise will lead to less weight gain than Olz/Sam alone (historical data) when measured at 4 weeks. People with schizophrenia, schizoaffective and bipolar disorder I,II and NOS are eligible. After informed consent, patients will undergo a full medical/psychiatric screening and be assessed for a reason to switch antipsychotic medication. Eligible subjects will receive 8 weeks of open label Olz/Sam. Over the first 4 weeks of treatment, all subjects will complete 4 weeks of aerobic exercise for 2 to 4 days a week. Olanzapine will be flexibly dosed over the first 4 weeks according to investigator discretion. The Sam dose will remain fixed at 10 mg for the duration of the study. Subjects will undergo comprehensive weight, metabolic, and symptomatic assessments before and after 4 weeks of exercise, and again at study end (8 weeks). Cognitive assessments will be done at Visit 2/Baseline and study end. This is a single site study.