The term "mesomorphic" refers to a body type characterized by a muscular and well-proportioned physique. Individuals with this body type typically have broad shoulders, a narrow waist, and a naturally athletic build. This classification is part of the somatotype theory developed by William Sheldon in the 1940s, which categorizes human bodies into three main types: ectomorphic, mesomorphic, and endomorphic. Mesomorphic individuals often find it easier to gain muscle mass and strength compared to other body types. They usually have a higher metabolism and can lose fat more efficiently. This body type is often associated with athletes and those who engage in regular physical training, making it advantageous for sports and fitness activities.