Despite sticking to his tried-and-true jogging and weight lifting routine, Mark noticed that he seemed to be losing muscle mass. Where his triceps once held his skin taut, flabbiness was starting to take over. But the real wake-up call came when he saw an older picture of himself. In the two years since the picture was taken, his pectoral areas had grown substantially—but it was all fat. When increasing his workouts didn’t help, Mark began to wonder if he had a health issue that he wasn’t aware of.