What causes weight gain using zoloft? if you eat the same & exercise, why do people gain on it? what mechanism is involved? does metabolism change?

Appetite increase: A number of psychiatric drugs, including most SSRIs (with the exception usually of fluoxetine or Prozac) cause an increase in appetite. I am not aware of evidence that they lower metabolic rate. Increasing physical activity and being more careful with eating, particularly craving-driven eating, generally helps. Drinking more water gives you a full sensation in your stomach; also carrots & celery