Definition and diagnostic criteria for orthorexia nervosa: a narrative review of the literature.

Aim: In some cases, detrimental consequences on health are generated by self-imposed dietary rules intended to promote health. The pursuit of an "extreme dietary purity" due to an exaggerated focus on food may lead to a disordered eating behavior called "orthorexia nervosa" (ON). ON raises a growing interest, but at present there is no universally shared definition of ON, the diagnostic criteria are under debate, and the psychometric instruments used in the literature revealed some flaws. This narrative review of the literature aims at assessing state of the art in ON definition, diagnostic criteria and related psychometric instruments and provides research propositions and framework for future analysis.

Methods: The authors collected articles through a search into Pubmed/Medline, Scopus, Embase and Google Scholar (last access on 07 August 2018), using "orthorexia", "orthorexia nervosa" and "obsessive healthy eating" as search terms, and filled three tables including narrative articles (English), clinical trials (English), and articles in languages different from English. The data extrapolated from the revised studies were collected and compared. In particular, for each study, the diagnostic criteria considered, the specific psychometric instrument used, the results and the conclusions of the survey were analyzed.

Results: The terms employed by the different authors to define ON were fixation, obsession and concern/preoccupation. Several adjectives emphasized these expressions (e.g. exaggerated/excessive, unhealthy, compulsive, pathological, rigid, extreme, maniacal). The suitable food and the diet were defined in different ways. Most of the papers did not set the diagnostic criteria. In some cases, an attempt to use DSM (edition IV or 5) criteria for anorexia nervosa, or avoidant/restrictive food intake disorder, or body dysmorphic disorder, was done. Specific diagnostic criteria proposed by the authors were used in few studies. All these studies indicated as primary diagnostic criteria: (a) obsessional or pathological preoccupation with healthy nutrition; (b) emotional consequences (e.g. distress, anxieties) of non-adherence to self-imposed nutritional rules; (c) psychosocial impairments in relevant areas of life as well as malnutrition and weight loss. The ORTO-15 and the Orthorexia Self-Test developed by Bratman were the most used psychometric tools.

Conclusions: The present review synopsizes the literature on the definition of ON, proposed diagnostic criteria and psychometric instruments used to assess ON attitudes and behaviors. This work represents a necessary starting point to allow a further progression of the studies on the possible new syndrome and to overcome the criticisms that have affected both research and clinical activity until now.

Level Of Evidence: Level V, narrative review.