John and Brad discuss how John lost and gained almost 16 pounds of muscle mass in less than a year. They review multiple DEXA scans over the years and how weight training and testosterone influenced John's ability to gain muscle and lose muscle. They also discuss how your bodyweight cannot tell you the whole story of what your body is made of, and how you can be wildly different in body composition at the same weight. The final message is weight training and a healthy testosterone level are critical for maintaining and gaining muscle mass.