Zoloft and most of the serotonin reuptake inhibitors available do cause weight gain....I started taking Zoloft two months ago. I noticed a gradual weight gain without a change in my diet. Then I went online and researched the topic a little bit, and realized Zoloft can cause a lot of weight gain....Paxil as well. Some doctors will decrease the Zoloft and add Topamax or Welbutrin.....this seems to help many people. You may want to ask your doctor about other alternative drugs. There are alternatives! Don't settle for Zoloft if you continue to gain weight and that is making you even more depressed!! If your doctor won't change or modify your medicine, I would maybe start looking for a new doctor. What's the point in taking an antidepressant, if its side effects CAUSE depressed feelings?