Depression and weight gain

Patient: Hello there. I have gained over a stone in weight sine taking anti depressents. I was on wellbutrin and then moved back to the UK. after a very stressful and overwhelming time my new doctor changed to mirtazapin. I did not work well on this. Very tired and weight gain (6 kgs). I went back and he has put me on 75mg of effexor. Less sedation which is great but my weight is increasing. This in turn makes me depressed ! – especially as I exercise and really really watch what I eat. He denies its the tablets – I think it must be. I have been doing weightwatchers and am saddened to see the weight increase. Help.!