Anorexia nervosa is a condition that actively causes significant weight loss by means of dieting, etc., significant weight loss of more than 15% of the normal average weight loss, or failure to achieve the desired standard of somatic growth before puberty, with delayed or stopped development. Most of those who present with this problem are teenage girls, but also young girls, and these patients are generally more fragile and perfection-seeking. Its incidence is higher in modern society, especially in developed countries, and the incidence in China is increasing. Anorexia nervosa has biological factors, but psychosocial factors play a large role in the development of the problem. The onset of the disease is directly related to psychological factors such as the pursuit of a slim body, family disagreements, stressful studies, and serious illness or death of important relatives. For those who want to make themselves slim, they initially try to achieve the goal through dieting, and they often avoid their families to take some measures to make themselves lose weight, such as eating very little, skipping breakfast, not eating meat, sometimes deliberately creating vomiting, taking laxatives, and excessive exercise. But over time, it causes anorexia and cannot extricate itself. About 50% of children have periodic gluttony and overeating during anorexia, and try to induce vomiting after eating; for children with severe psychological stimulation or psychological burden, depression causes loss of appetite and anorexia. The child eats less, refuses to eat, and induces vomiting, thus losing weight quickly, losing weight, and losing energy, but even so, some patients still think they are not thin enough and feel fat. Long-term anorexia not only leads to malnutrition, metabolic and endocrine disorders, but also leads to many physical and mental disorders, such as disorders of water and electrolyte balance, poor resistance, anxiety, irritability, insomnia, inattention, compulsive thinking and abnormal behavior; delayed growth and even cessation due to endocrine disorders, amenorrhea in post-pubertal girls, etc. The course of anorexia nervosa is long, and some patients can remit on their own, but if it continues for a long time, the consequences are serious and difficult to treat, and the mortality rate of serious cases is high, reported to be 6-20%, so it should be detected and treated early. In the diagnosis, we should first exclude eating disorders caused by other diseases, and in treatment, doctors should take medication and psychotherapy according to specific conditions, such as medication with antidepressants and antipsychotic drugs, psychotherapy with supportive therapy, positive reinforcement method, family psychotherapy, etc. In severe cases, nutrition therapy is needed in conjunction with a nutritionist.