I'm on Prozac for my Anxiety and for the first week I didn't lose weight then the next week I lost 6 pounds. I think your body has to get used to it and its also Important to take your meds at the same time each day. I one time took my meds at night instead of morning (I forgot to take them) and it made me either hold water or not lose. (Who can tell the difference?) Well that's my two cents worth