I have no direct experience with either of these types of meds, but I've experienced a lot of weight gain from a tricyclic antidepressant. Those change your metabolism, not your appetite, so you gain weight while eating the same amount.

Unfortunately, exercise didn't help me - it's true generally for women that we can't lose fat from exercise alone. Dieting helped to a point, but I had to restrict my calories so severely it was affecting my ability to concentrate. I didn't lose the weight for good until I got off the med (and then, it came off not only without trying, but without my even being aware of it until I'd already dropped 7# and someone else pointed it out).

Can you ask your doctor to try something else? Or have you already exhausted most of your options?