Abstract
AIM: Orthorexia Nervosa (ON) describes a pathological obsession with proper and high-quality nutrition that is necessary to research further in order to elucidate its prevalence and correlates which may bear implications for prevention and treatment. The aim of this study was to review studies that report the prevalence of ON in people who exercise, calculate an overall prevalence through a random-effects meta-analysis approach and investigate the association of ON prevalence using a random-effects meta-regression. In addition, a sub-group-analysis based on ON-instruments and a sensitivity analysis excluding students samples, were conducted. METHOD: Systematic searches were conducted in the following online databases: PubMed, Embase, Web of Science, PsychInfo, CINAHL, Google Scholar and OpenNet. The following search terms were used: Orthore* AND (prevalenc* OR incidenc* OR frequen* OR cut-off OR epidem*). A total of 613 unique hits were reviewed by two blinded authors, and 24 studies were coded and assessed for risk of bias (Holy et.al). The meta-regression included three independent variables (sex, type of sport, and sample size). RESULTS: The overall prevalence of ON in the exercising population was 55.3% (95% CI 43.2-66.8). Cochran's Q was 11,436.38 (df = 23, p < 0.0000), and the I(2) was 98.4%, indicating high heterogeneity across studies. The sensitivity showed an overall prevalence of 51.3% (95% CI 51.3-70.0). There was a significant difference in prevalence estimates based on the instruments used (Q(bet) = 33.6, df = 2, p < 0.01). DISCUSSION: The overall prevalence of ON in exercising populations was very high. The between-study disparity was large and was partly explained by the ON-instrument administered. One fourth of the studies had a moderate risk of bias. The majority of the studies did not specify relevant demographic information about the sample, and information about the type of sport was frequently missing.