Lean body mass refers to the weight of everything in the body except fat, including muscles, bones, and organs. It is essential for overall health, as it contributes to a higher metabolic rate, better physical performance, and improved strength. Maintaining a healthy level of lean body mass helps support weight management and reduces the risk of chronic diseases. It is particularly important as individuals age, as muscle mass typically declines, leading to increased fat accumulation. Strategies such as regular strength training and balanced nutrition can help sustain lean body mass over time.