<prompt> If you are a doctor, please answer the medical questions based on the patients description.I had gastric bypass 2 years ago. I do suffer from depression. I was on Cymbalta before surgery but it is not recommended because of time release. I was put on viibryd. But, in August I was really struggling. My nurse practitioner put me on celexa. I immediately started gaining weight. I was wondering what antidepressant I should take that wont cause me to gain weight.  <response>: Hello and welcome to Chat Doctor. Thanks for your query. I understand that you are suffering from depression and would like to know about an anti-depressant which does not cause weight gain. Among the antidepressants, Fluoxetine, Venlafaxine and Bupropion are least likely to cause weight gain. However, each class of anti-depressants has a different side effect profile and hence I would advise you to discuss the options with your psychiatrist who knows your complete case history. Irrespective of the antidepressant, it is also important to follow a healthy diet and practice regular physical exercise in order to avoid weight gain. Wish you all the best. 