Anorexia nervosa, also known as anorexia nervosa, is a psychological eating disorder characterized by intentional dieting leading to weight loss. It often occurs in adolescence (about 85% of the cases occur between the ages of 13 and 20), and the incidence rate in females is about ten times higher than that in males. The illness can last from a few months to several years. Although some people were overweight before dieting, they continue to diet until they reach a normal weight; others need to maintain their weight due to their careers, such as singers, actors, models and athletes, who have a higher incidence rate. Anorexia also often comes from wealthier families, and other family members of the patient are more likely to have similar symptoms.