I just started taking phentermine 30mg. My average calorie intake on it is 800 a day. Im not trying to be that drastic but it kills my appetite(which I guess is the point) Im going to the gym 3-5 times a week. Running, eliptical, and twice a week the bodypump weight class. Weight is coming off but I dont want to loose muscle I want to loose fat. How do i know which im loosing. Do I need to force myself to a higher calorie diet. 1000 or 1200? Or will be ok as long as Im working out? Any Advice.