Antidepressants are prescribed for depression, for the most part, and most people who take them have trouble getting out of bed without them. (overstated, but that's the direction). Seems to me that most SSRIs cause weight stall, not loss. The weight loss, if any, comes because the medication allows people to get out of bed and move.

My experience is that most depression is organic, caused by imbalances in the brain, rather than situational. Situations pass and people recover naturally--imbalances don't go away on their own.