The term "asthenic" refers to a body type characterized by a slim, delicate build and low muscle mass. Individuals with an asthenic physique often have narrow shoulders, a thin frame, and long limbs. This body type is one of the three somatotypes identified by William Sheldon, alongside endomorphic and mesomorphic types. Asthenic individuals may have a higher metabolism and may find it challenging to gain weight or muscle. This body type is often associated with certain health conditions, as a lower body fat percentage can impact overall energy levels and physical endurance. Understanding body types can help in tailoring fitness and nutrition plans.