I was on Lithium in the past and only gained about
15-20lbs, but losing even an ounce was next to impossible. I changed my diet and even exercised regularly, but could not get the weight off. Unfortunately, the rx is known to make people gain weight, as Serafena suggested you should probably bring your concerns up with your pdoc. There are other mood stabilizers that are weight neutral. Please let us know what you decide.