Anorexia nervosa com dangerously low body weight meets all definitional requirements for Anorexia nervosa, com BMI under 14.0 kg/m² in adults or under the 0.3rd percentile for BMI-for-age in children and adolescents. In the context of Anorexia nervosa, grave underweight status is an important prognostic factor that is associated com high risk of physical complications and substantially increased mortality.