Sertraline and weight gain?

I am taking sertraline at the moment and easing myself off propranolol. I have GAD and depression, and recently had a relapse. I have also been referred back to a counselor, and am awaiting the appointment. I am worried about weight gain on sertraline, as half of my battle with anxiety and depression was about my image and weight. I don't know what to tell the doctor, do i tell him i am worried about this? I feel in such a rut at the minute, after finally starting to feel better, i feel worse!!!