What weighs more, muscle or fat?

Muscle and fat do not have any inherent weight differences, as is popularly described. Five pounds of muscle weighs the same as five pounds of fat. However, the idea trying to be explained is true - it is a matter of density. Muscle is much more dense than fat.

If a portion of muscle and a portion of fat take up the same space (that is, having the same volume), then the portion of muscle will in fact weigh more. Additionally, muscle is less lumpy in appearance than fat, and fat has a higher tendency to be located in undesirable places.