Hi, I'll just cut right to the point. I'm a 16 year old male, I'm 5 ft and 7 inch. I currently weigh 138 pounds and have been on a long-term diet for several months now, lost roughly 40 pounds. I still have some body fat left on my stomach. I did some calculating (in case it will help you guys out) My BMR is 1667.84 and my daily calorie maintenance is 2363. Now my goal is to gain a 6 pack, good metabolism, and a toned lean body. My only problem is that I want to gain muscle, but not gain body fat back. I'm not sure of how many calories I should be taking in daily, when i work out that day or when it's a rest day? I work out 5 times a week. One day I do upper-body weight lifting, one day I do ab work, one day i do leg, and two days i do cardio. I also run on the treadmill everyday i work out at the end of the workout routine, burning 600 calories on the treadmill. On a cardio day, I burn 800 calories on the treadmill. One major question i have is if i should workout after done eating for the day? Should I try to be burning off all the calories i take in for the day, or should i just use the running as a way to burn off some of the calories I've taken in that day? How many calories should I take in to build muscle, but not take in too much? Any advice will help me out...thank you for your time and assistance.