<s>[INST] 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. [/INST] 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. </s>