Validation of the inflexible eating questionnaire in a large sample of Chinese adolescents: psychometric properties and gender-related differential item functioning

Purpose: The aim of this study was to provide preliminary psychometric evidence for the Chinese version of the Inflexible Eating Questionnaire (C-IEQ) among a large sample of Chinese adolescents. Methods: For testing the psychometric properties of the C-IEQ, a total of 2241 (M_age = 13.91 years; 46.4% boys) adolescents from mainland China responded to the survey. Confirmatory factor analysis (CFA) was used to examine the factor structure of the C-IEQ. Measurement invariance by gender was examined by both multi-group CFA and differential item functioning (DIF). Convergent validity of the C-IEQ was assessed via examining the correlations between the C-IEQ scores and theoretically related constructs (e.g., orthorexia nervosa symptomatology, eating disorder symptomatology, and body image inflexibility). Results: The unidimensional structure with correlated errors of the C-IEQ showed good model fit (χ² = 1674.05, df = 44, p < 0.001; CFI = 0.93; TLI = 0.91; RMSEA = 0.13; SRMR = 0.06). The C-IEQ had an adequate internal consistency (α = 0.89) and demonstrated strong measurement invariance across genders. Moreover, the scores of the C-IEQ showed significant correlations with theoretically correlated constructs: orthorexia nervosa symptomatology (girls; r = 0.53 p < 0.001, boys; r = 0.45 p < 0.001), eating disorder symptomatology (girls; r = 0.32 p < 0.001, boys; r = 0.25 p < 0.001) body image inflexibility (girls; r = 0.41 p < 0.001, boys; r = 0.36 p < 0.001), suggesting good convergent validity of the C-IEQ. Conclusion: The C-IEQ showed good psychometric properties in a sample of Chinese adolescents and can be used in future studies to assess eating-specific psychological inflexibility among Chinese adolescents. Level of evidence: Level V, cross-sectional descriptive study.