I've been on Prozac since I was in 4th grade and I'm 22 now. I gained weight even though the side effect is weight loss, but I didn't gain weight until I was a senior in high school so I think it's due to my birth control and not playing sports anymore, not the Prozac. but who knows. Anyways I've lost 20lbs, SSRI doesn't seem to affect my weight loss. Good luck!