Sarcopenia is the degenerative loss of skeletal muscle mass, quality, and strength associated with aging.
Cachexia or wasting syndrome is loss of weight, muscle atrophy, fatigue, weakness, and significant loss of appetite in someone who is not actively trying to lose weight. Anorexia nervosa is an eating disorder characterized by immoderate food restriction and irrational fear of gaining weight, as well as a distorted body self-perception.
Neuromuscular disease encompasses many disorders and ailments that impair the function of tissue. Neuromuscular disease may directly affect muscle tissue or be a consequence of diseases of the nervous system which consequently alter innervations of muscle tissue.