What is anorexia nervosa?

Anorexia nervosa is an eating disorder marked by an intense fear of gaining weight, a refusal to maintain a healthy weight, and a distorted body image. People with anorexia nervosa have an abnormal loss of appetite for food, try to avoid eating, and eat as little as possible.

This answer is based on source information from National Cancer Institute.

Anorexia (or anorexia nervosa) is an eating disorder centered around an obsessive fear of weight gain. Anorexia involves self-starvation and excessive weight loss. Although anorexia is a psychological disorder, the physical consequences are serious and sometimes life-threatening.

Anorexia nervosa is an eating disorder in which preoccupation with dieting and thinness leads to excessive weight loss. If you suffer from this disease, you may not acknowledge that weight loss or restricted eating is a problem, and you may "feel fat" even when you're emaciated. Women with anorexia intentionally starve themselves or exercise excessively in a relentless pursuit to be thin, losing more than 15% of their normal body weight. Roughly half of all women suffering from anorexia never return to their pre-anorexic health, and about 20% remain chronically ill. The death rate for anorexia is among the highest of any psychiatric illness. The deaths are about evenly divided between suicide and medical complications related to starvation