Body composition refers to the relative amounts of fat and muscle in the body, differing from weight alone, which does not account for these differences. Two individuals may weigh the same, but their composition can significantly influence health and fitness levels. A higher percentage of muscle mass typically correlates with improved metabolism and overall strength, while higher fat percentages can increase health risks. Measuring body composition, often using tools like bioelectrical impedance or dual-energy X-ray absorptiometry, provides a clearer picture of fitness and helps guide weight management strategies.