Suggest Treatment For Weight Gain After Hysterectomy

Hi! I am 8 mos post complete hysterectomy and have gained about 40 pounds. I am on estratest and 150 mg of effexor to rid my hot flashes. It seems no matter how little calories I consume (1200 cal each day) I can not lose any weight! Can you pls tell me what I need to do to get back to being fit? Would weight watchers help? I just turned 40, 5'7",188lbs...please help me. Thank you in advance!