Anorexia nervosa is an eating disorder that is mostly seen in adolescents and young women and has three characteristics 1, excessive dieting: excessive restriction of high-calorie foods, eating significantly less, not eating staple foods for many days in a row, eating only a small amount of vegetables, fruits or diet foods. Some patients will visit the hospital several times with gastrointestinal and other somatic discomfort, and there are no obvious organic abnormalities. 2, the perception of their own body shape or weight disorders: manifested as always feel fat, in the eyes of outsiders, very slim, and even some patients are thin skin and bones, but they still feel some fat, and set themselves a “ideal” weight standard is difficult to achieve, and work hard for it. Some patients, in addition to dieting, may exercise excessively, vomit after meals, use laxatives, or use enemas, etc. Especially some patients may occasionally overeat. They are more likely to take emetic induced diarrhea to stop gaining weight. 3. Significant weight loss and physiological disorders: malnutrition, physical weakness, endocrine disorders, menstrual disorders or even menopause; children who are growing in height and weight growth are limited; inattentiveness, impatience, impulsiveness and depression, etc., which have a great impact on the individual’s school, life and work.