What Is Body Composition? - Overweight Versus Overfat
What is body composition? It is used to evaluate the percentages of fat, muscle and bone in our bodies. Muscle tissue takes up less space in our body than fat tissue does, therefore our body composition, as well as our body weight, determines how lean we actually are.
Because of this you can have two people who are both the same height and same weight that can look completely different from each other, that's because they have a totally different body composition.