While it's true that some antidepressants/antipsyhotics have "weight gain" listed as a side effect, the reason it happens is because these medications affect your brain's ability to detect when you are full. While you won't always feel like you're starving (like patients who suffer from Prader-Willi Syndrome), you will feel the need to eat more than usual. This is STILL not an excuse! CICO still applies. Careful monitoring of your daily caloric intake will prevent weight gain. Eating whole foods that are rich in fibre will also help. Weight gain due to these medications can also be negated by exercising. Studies have shown that exercise can be as effective, or even morso, than antidepressants for patients suffering mild to moderate depression. PS. Sorry I don't have a legitimate source for the weight-gain information. This information is based on my own personal experiences with antidepressants, plus information given to me by my aunt who is a pharmacist.