Lean body mass is a term often used in the fitness and medical communities to refer to the amount of non-fat tissue in the body. It includes muscle, bones, organs, and other tissues that are not fat. Your lean body mass makes up the majority of your total body weight. Lean body mass can be affected by many factors, including age, diet, activity level, and genetics. It is also often used as a measure of fitness and health. A high lean body mass indicates that a person has a lot of muscle and is generally in good health. A low lean body mass may mean a person needs to gain muscle or lose fat. Different ways to measure lean body mass include the of use skinfold calipers, bioelectrical impedance analysis, and dual-energy x-ray absorptiometry. There is also a lean body mass (LBM) formula to calculate your approximate LBM faster. The equation is LBM = body weight - (body fat % x body weight). For example, a 200 lb man with 20% body fat has 160 lbs of lean body mass. The average person