One of the three classic body types in somatotype theory, describing a naturally muscular, powerful build with broad shoulders, narrow waist, and efficient muscle gain. Mesomorphs tend to carry moderate body fat and respond quickly to strength training, making the type common among athletes in power sports. The classification, developed by William Sheldon, also attempted to link physique to temperament, claims modern science does not support. In sports nutrition, body type informs general expectations about training response and energy needs, but individual assessment matters far more than category. The mesomorph ideal influences fitness culture’s image of the athletic body.