Development and Validation of the Test of Orthorexia Nervosa (TON-17)

Abstract

This study aims to develop and validate a new self-report questionnaire to measure orthorexia nervosa (ON). Based on a current review of the scientific literature and interviews with people at risk of orthorexia, 40 items were selected to test orthorexia nervosa (TON-40). A total sample of 767 individuals (M = 26.49, SD = 9.66, 56.98% women) participated in the study. The exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and composite construct analysis (CCA) were performed to find an appropriate model of sufficient reliability and validity and stable construction. Convergent validation was performed regarding the correlation of the TON-17 with another measure of ON (ORTO-15), eating disorders (the EAT-26 and DEAS), healthy behavior (the HBI), quality of life (the Brief WHOQOL), physical health (the GRSH), anxiety (the GAD-7), depression (the PHQ-9), and obsessive-compulsive disorder (the OCI-R). Gender, Body Mass Index (BMI), and the medical reasons for a restrictive diet were also examined. As a result of the structural analyses, the number of items was reduced from 40 to 17. The best fit indices of the TON-17 were found for the hierarchical bi-factor model, with three lower-order factors (Control of food quality, Fixation of health and healthy diet, and Disorder symptoms) and one general higher-order factor (Orthorexia). According to the 95th percentile method of estimation, the prevalence of ON was 5.5% for the TON-17 total score. The TON-17 scale and subscales showed good psychometric properties, stability, reliability, and construct validity. The TON-17 indicated a positive relationship with the ORTO-15, EAT-26, DEAS, HBI, OCI-R, GAD-7, and PHQ-9. TON-17 can be considered as a useful tool for assessing the risk of ON.

The Mediating Role of Orthorexia in the Relationship between Physical Activity and Fear of COVID-19 among University Students in Poland

“…Orthorexia was measured with a 17-item Test of Orthorexia Nervosa (TON-17) questionnaire, with a response scale ranging from 1 (totally disagree) to 5 (totally agree) [47]. All items form a general score (by addition) and can also be divided into three subscales: control of food quality (CFQ), fixation on health and healthy lifestyle (FHHL), and disorder symptoms (DS).…”

“…The prevalence of orthorexia depends on the diagnostic cut-off criteria, the instrument used, or geographic region, and ranges between 1% to 89%, as suggested by review studies [43][44][45]. However, Varga et al [45] found the average prevalence of ON to be 6.9% in the general population, while rates between 1% and 7% were estimated by using Düseldorf Orthorexia Scale (DOS ≥ 30) [46], and 5.5% using Test of Orthorexia Nervosa (TON-17 ≥ 61) [47] in the Polish sample. However, the prevalence of ON was rarely assessed among university students.…”

“…In particular, ON is positively related to eating disorders (EDs), obsessive-compulsive traits, stress, anxiety, and depressive symptoms, and negatively associated with psychological wellbeing and life satisfaction [40,52,53]. Recent studies also found correlations between ON and EDs, healthy behaviors, anxiety, obsessive-compulsive disorder (OCD), and depression [47,54].…”

Obsessed with Healthy Eating: A Systematic Review of Observational Studies Assessing Orthorexia Nervosa in Patients with Diabetes Mellitus

“…Barbanti [39] was the only study that applied the Bratman Orthorexia Test (BOT) [2]. None of the studies used the more recently developed ORTO-R [43], the Test of Orthorexia Nervosa (TON-17) [44], the Orthorexia Nervosa Inventory (ONI) [45], the Barcelona Orthorexia Scale (BOS) [46], the Düsseldorf Orthorexia Scale (DOS) [47], the Eating Habits Questionnaire (EHQ) [48], or the Teruel Orthorexia Scale [49].…”

Adventures of Clinical Psychology

“…After a structural analysis, the number of items was reduced from 40 to 17 (TON-17), including three subscale factors (Control of food quality, Fixation of health and healthy diet, and Disorder symptoms) in a hierarchical, bi-factor structure. The study demonstrates that the TON-17 scale has good psychometric properties, stability, reliability, and construct validity, and therefore it could become a promising tool for assessing the risk of orthorexia nervosa [1].…”