Abstract
Atypical anorexia nervosa (atypical AN) appears to be a heterogeneous disorder under the current diagnostic system. Though the body mass index (BMI) cutoff point of 18.5 kg/m2 is a criterion that distinguishes atypical AN from AN, the cutoff may not be universally applicable as the norms for BMI vary and can be affected by several factors, including cross-country differences and social determinants. It is unfortunate that we do not yet have reliable or widely available criteria other than BMI for the diagnosis of atypical AN. Additional relevant markers of atypical AN are needed in future diagnostic systems.