What function does lean body mass serve?

Lean body mass plays a critical role in overall health and fitness, primarily by contributing to metabolism and supporting various functional activities. Lean body mass, which includes muscles, organs, bones, and other non-fat tissues, is metabolically active. This means that it consumes energy even when at rest, thereby influencing an individual's resting metabolic rate.

Having a higher percentage of lean body mass can enhance physical performance, improve strength, and facilitate better movement and endurance during various activities. Moreover, lean body mass supports everyday functional activities, such as lifting, carrying, and maintaining proper posture, which are essential for overall quality of life.

By contrast, the other options do not accurately reflect the significance of lean body mass. It does not decrease metabolism or reduce physical performance, nor is its primary function energy storage. In fact, its role in fitness and health is significant and cannot be overlooked.