Factor structure and psychometric properties of the German version of the Reward-based Eating Drive scale

Objective: The reward-based eating drive (RED) scales are well-established self-report scales that measure reward-related eating behavior. However, German versions of the RED has not yet been created and validated. Therefore, the aim of the present study was to develop and psychometrically evaluate a German version of the RED. Method: A German university sample (N=311 medical undergraduates) completed a survey including the RED-9 and the RED-13, as well as several related measures, to test the established factor structure using a confirmatory factor analysis. Construct validity was assessed by correlation analysis with standardized and internationally established questionnaires measuring reward-related eating. Results: The German 9-item RED (RED-9) with the 3-factor model showed the best psychometric properties in terms of fit indices with acceptable internal consistency, good item rest correlation, and good construct validity with other reward eating scales. There was also a positive association between the German RED-9 total score and BMI. Conclusions: In conclusion, the German RED-9 is a valid and reliable instrument for the assessment of reward-related eating behavior in non-pathological populations. Further research is needed to better understand associations among reward-related eating, obesity, and diabetes in the German population.