Just one other thing to throw into the mix is that lean body mass tends to correspond with a higher BMR (basal metabolic rate), therefore comparing someone weighing 200 lbs that is flabby vs. fit, the fit person burns more energy at rest while not working out resulting in an increase in calories burned throughout the day. Keep in mind that working out is a great way to burn calories, but truthfully is only a drop in the bucket when compared to the amount of energy your body burns on a daily basis just to keep itself running.