Progress in research on orthorexia nervosa is still hampered by the use of the ORTO–15 and its modifications

The ORTO–15 is an unreliable and invalid measure for orthorexic symptomatology. Revisions of this scale by removing items or changing scoring procedures do not solve these problems and do not contribute to consistent literature that increases knowledge about ON. As the ORTO–15 and its modifications are still the most often used measures in studies on ON, it seems necessary to reiterate the recommendations made earlier by others: neither the ORTO–15 nor its other versions should be used in studies on ON. Instead, alternative measures that have been developed in the past 10 years should be preferred.