Serotonin is an anorexient neurotransmitter. But if I am right, antidepressant drugs like SSRIs increase the amount of serotonin in the brain.
So why do antidepressants increase body mass if serotonin is an anorexient?
Edit : You can find here that antidepressants are associated with weight gain : https://www.medicalnewstoday.com/articles/319527
I also was taught that in a pharmacology class.
Edit2 : What I found is one reason is that the improvement in mood as a cause of these drugs may lead to an improvement in apetite and thus weight gain, but is this the only reason?