Anorexia nervosa (usually just called anorexia) is an eating disorder.
People with anorexia think that they are fat, or desperately fear becoming fat even if they are very skinny. To try to lose weight, anorexics do not eat enough. When they do eat, they do not eat the amount of food their body needs, in an effort to avoid gaining weight. This causes them to lose too much weight too quickly. This is very harmful to a person's body. There are various treatments for anorexia. One example is the Maudsley Method. This type of treatment is for patients who are 18 or younger. Two thirds of adolescent anorexia patients are 'recovered' at the end of this treatment.
Anorexia nervosa Facts for Kids. Kiddle Encyclopedia.