What BMI indicates a diagnosis of anorexia nervosa?

A diagnosis of anorexia nervosa typically includes specific criteria related to weight and body mass index (BMI). A BMI of ≤ 17.5 kg/m² is often referenced as a threshold for underweight status, aligning with the diagnostic criteria set forth by the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition).

In the context of anorexia nervosa, individuals usually present with significantly low body weight, which is defined as weighing less than minimally normal for their age, sex, and development. In clinical settings, practitioners use BMI as a quantifiable measure of this low weight status. The threshold of 17.5 kg/m² serves as an important indicator, as individuals with a BMI below this level are more likely to exhibit the severe weight loss and associated health risks characteristic of anorexia nervosa.

Higher BMI thresholds do not adequately capture the severity or the clinical implications of the disorder, as individuals with a BMI of 18.5 or 20 kg/m², while considered underweight, may not meet the clinical picture of anorexia nervosa where the emphasis is on more severe malnutrition. Thus, the most appropriate cutoff for diagnosing anorexia nervosa is a BMI of ≤ 17.5 kg/m