Fat-free mass , or muscle mass, is the main determinant of how many calories you burn. So, consider a body composition measurementto get a better idea of your energy needs. In this, the first of two blogs, we will focus on the bulking phase of bodybuilding. A cutting post will be featured in part two of Bodybuilding 101. "And because your cardio is timed, your weight sessions are timed, and everything is around the clock, my time management is pretty good now."