Diagnostic criteria: restriction of energy intake relative to requirements, leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health. Significantly low weight is defined as a weight that is less than minimally normal or, for children and adolescents, less than that minimally expected. In partial remission: after full criteria for anorexia nervosa were previously met, Criterion a (low body weight) has not been met for a sustained period, but either. Criterion b (intense fear of gaining weight or becoming fat or behavior that interferes with weight gain) or criterion c (disturbances in self-perception of weight and shape) is still met. The level of severity may be increased to reflect clinical symptoms, the degree of functional disability, and the need for supervision: mild: bmi 17, moderate: bmi 16 16. 99, severe: bmi 15 15. 99, extreme: bmi < 15.