Orthorexia is a recent construct describing an unhealthy and extreme concern for healthy food. To date, its relationship with other eating disorders (EDs) remains unclear, and little is known about the development of this condition. Current literature suggests that a thorough knowledge about nutrition and alimentation, as in the case of experts in the field of dietetics, could foster the development of orthorexic tendencies. The aim of this study was to compare orthorexia between ED patients, student dietitians and general population.