Resting Metabolic Rate (RMR) is the single greatest determining factor of Calorie expenditure. Simply put, the more muscle you have (not to be confused with muscle mass) the more calories you burn. While physical activity such as exercise is important, the activity itself is short-term relative to the course of a 24-hour period. Knowing your RMR will also tell you the minimum number of Calories you need to consume support basic body function.
RMR Calculator
