Body composition differs from body weight as it focuses on the ratio of fat to lean mass in the body. Body weight alone does not differentiate between muscle, fat, and other components, potentially misleading assessments of health and fitness. A person with a higher proportion of muscle might weigh more but have a healthier body composition compared to someone with higher body fat versus lean mass. Understanding body composition helps tailor fitness and nutrition plans to improve overall health and ensure individuals maintain a healthy weight relative to their composition.