What is Body Composition? It is the combined percentages of fat, bone, water, and muscle in human bodies. How is it that someone can weigh the same but look smaller? The biggest myth of all is that muscle weighs more than fat. That's not true. The reason someone could look smaller and weigh more or not see the scale move at all is because muscular tissue takes up less space than fat tissue. • A pound of fat is bulky, fluffy and takes up the space of a grapefruit. • A pound of muscle is hard, den