For the last few months my doctor had me on Citalopram HBr (Celexa) 40mg. It made me extremely tired and It felt like I became immune to it. So Today I was prescribed (Zoloft) Sertraline HCL 50mg. I haven't made the switch yet i have to gradually move into it i cuting the pills in half. So I actually would not have taken my first half pill of this until next Thursday. So I don't know how much help I am right now. Through the Celexa I actually lost weight. It makes you so drained and exhausted your actually forget to eat. I'm 18, 5/3, and was 99lbs before I started any antidepressants. Today I'm 93lbs. I've only started months ago. So if I were you I would just be worried about weight loss. You're small like me so you won't gain anything. Just remember to make yourself eat, because I eat like a cow and still lose weight! It's for severe depression so regardless to if your depression has caused weight loss or loss of appetite or not has nothing to do with it. Its all about your symptoms, your situation, how long you've been undergoing it, etc. Everyone is different so my outcome could be totally different than yours since we're medicated for simular but very different reasons. Hope this helps!