Prevalence of orthorexia nervosa is less than 1 %: data from a US sample

Thomas M. Dunn, Josh Gibbs, Noelle Whitney, Amy Starosta

Orthorexia nervosa, or pathological dieting based on being "healthy," has been of growing interest. Clinical data are limited to less than a half-dozen case studies reporting instances of medical problems due to healthful eating. However, more than a dozen studies using a measure to identify orthorexia, the ORTO-15, report very high prevalence rates in non-clinical samples. Point prevalence rates are reported from 6 % to nearly 90 %. Such variability could be due to cultural issues or psychometric problems with the instrument. This study examines prevalence rate of orthorexia in a US sample. The ORTO-15 was administered to 275 US college students along with other questions regarding diet, exercise, and health. While the ORTO-15 indicated a prevalence rate of 71 %, only 20 % of the sample endorsed a dietary practice of removing a particular food type (e.g. meat) from their diet. Those who endorsed following a vegan diet had the highest (less pathological) mean ORTO-15 score. Further, when classifying participants based on their seriousness about healthy eating and whether their diet had led to impairment in everyday activities and medical problems, less than 1 % of the sample fell into such a category. As in other countries, a large proportion of a non-clinical US sample scored in the orthorexia range on the ORTO-15. However, this instrument is likely unable to distinguish between healthy eating and pathologically healthful eating. Our estimate is that orthorexia nervosa like anorexia nervosa and bulimia nervosa, is not a common condition.