Muscle is denser than fat, meaning it takes up less space per pound. On average, muscle tissue is about 18% denser than fat. This density difference can lead to the appearance of greater weight loss with fat loss compared to muscle gain, even when the scale shows a similar numerical change. So, while a pound of muscle and a pound of fat both weigh the same (one pound), muscle takes up less volume, contributing to a leaner and more toned physique.