1. the deliberate restriction of caloric intake due to a reduced appetite - often thought to be part of a drive for thinness. Anorexia may also lead an individual to over-exercise in order to lose weight and expend calories. Generally, this is associated with a psychological disorder but may also be associated with hypopituitarism. See also anorexia nervosa. 2. the loss of appetite for other human desires, for example sex.