This is objectively false. Schizoaffective disorders, bipolar disorder, and most other serious mental illnesses are not treated with diet and exercise, nor is bad diet or poor exercise the cause of serious mental illnesses.
I said CAN be treated. Whether or not mental illnesses are COMMONLY treated that way is another argument. It is a fact that all serious mental illnesses are greatly influenced by diet and exercise, including Schizoaffective disorders and bipolar disorder
