Atypical Anorexia Nervosa is not atypical at all! Commentary on Walsh et al. (2022).

The introduction of atypical anorexia nervosa (atypAN) as a new diagnosis in DSM-5 has advanced the field by expanding awareness that individuals of all weights can have an eating disorder. However, many clinical and research questions remain, particularly pertaining to whether atypAN and anorexia nervosa (AN) are different conditions or the same condition across the weight spectrum. In this issue of the journal, Walsh et al. describe the results of their systematic review demonstrating that the level of eating disorder-specific psychopathology is significantly higher among individuals with atypAN than among controls, and as high or higher than among individuals with AN. Levels of noneating disorder psychopathology are similar. Individuals with atypAN experience many of the medical complications associated with AN but at a lower frequency. The finding that the clinical features of atypAN are not substantially different from AN supports the possibility that atypAN and AN are the same condition. Further research on epidemiology, genetics, treatment, course and outcome is required to determine whether atypAN and AN are the same or different, but there is a need to update and refine existing terminology and diagnostic classification.