Turkish Version of the New Instrument for Orthorexia Nervosa—Test of Orthorexia Nervosa (TON-17): A Validity and Reliability Study

This study aimed to adapt the Test of Orthorexia Nervosa- (TON-17) into Turkish and verify its validity and reliability. The study included 539 adults with a mean age of 30.2 ± 12.26 years. A reliability analysis was performed, along with a confirmatory factor analysis to test its construct validity. The time-invariance of the scale was examined by test–retest analysis, and its convergent validity was evaluated by a correlation analysis conducted to test the relationships between the scale and Eating Attitudes Test-26 and Obsessive Beliefs Questionnaire-9. Analyses were conducted using SPSS Version 28 and the AMOS-24 software. The Cronbach’s α internal consistency coefficient of the total scale was found to be 0.82, suggesting a strong internal consistency. The Cronbach’s α values of its factors were 0.68 for the “control of food quality”, 0.64 for the “fixation on health and a healthy diet”, and 0.73 for the “disorder symptoms”. In addition, the test–retest reliability was found to be 0.87 for the total scale, suggesting excellent reliability. Most of the fit indices (CMIN/df, RMSEA, AGFI, NFI, and TLI) of the scale were acceptable, and the GFI indicated a good model fit. This study shows that the Turkish version of TON-17, which is a new tool with a three-factor structure to evaluate orthorexia, is a valid and reliable scale.