Natural History
The onset of anorexia nervosa often follows new life situations in which the patient feels inadequate or unable to cope. Such changes may be biological, such as the onset of puberty; psychological, such as the stages of adolescence; or social, such as entering high school or college. The onset of anorexia nervosa may also follow the breakup of a relationship or the death of a relative or friend.

Typically, anorexia nervosa begins in individuals who are at normal weight or are slightly to moderately overweight. Dieting is initially supported, even actively encouraged, by family and friends as well as, in many cases, by dance teachers and sports coaches. The patient is thus praised for the initial weight loss and takes pleasure in the achievement. Once the original weight reduction goal is attained, however, a new one is immediately set. Ostensibly, this is for “insurance” to offset future weight gains, but weight loss in the pursuit of thinness soon becomes an objective in itself.

Patients usually come to medical attention not because of weight loss but because of complaints such as amenorrhea, edema, constipation, or abdominal pain. They may complain of specific “food allergies” and ask for aids in dieting such as diet pills or diuretics. Patients may also present as medical emergencies, since the complications of dieting or vomiting, such as dehydration and fluid and electrolyte imbalance, may be severe. The patient may be brought in by parents, who become worried when weight loss is extreme or are alarmed by bizarre eating habits and personality changes.

The course of anorexia nervosa is variable. There may be a single episode with complete recovery, or multiple episodes spanning many years. A single episode may also be chronic and unremitting. Complete or partial recovery may occur spontaneously in some cases or may follow treatment. Both single episodes and fluctuating courses may progress to death.