In the context of fitness, how is "lean mass" defined?

The definition of "lean mass" in the context of fitness encompasses the weight of muscles, bones, and organs, while explicitly excluding fat. This distinction is important because lean mass is a critical component of overall body composition and is often a focus in fitness assessments and training programs.

By understanding that lean mass includes not just muscle tissue but also bones and vital organs, one can appreciate the role this mass plays in metabolic processes, strength, and overall health. It reflects the body's functional capacity, which is crucial for physical performance and wellness.

In contrast, definitions that limit lean mass to just the weight of muscles and bones do not account for the contribution of organs, which also contribute significantly to body composition. Furthermore, definitions that include body water or simply reflect total weight minus fat mass can be misleading, as they do not encapsulate the broader definition of lean mass as it relates to health and fitness.