The Regulation of Eating Behavior Scale (REBS) is one of the most popular measures to assess why people regulate their eating behaviors. However, few studies have examined its psychometric properties and problems with discriminant validity have been identified in previous research. The present study (re)examined the factor structure and criterion-related validity of the REBS using confirmatory factor analysis (CFA), exploratory structural equation modeling (ESEM), and bifactor (S-1) modeling in a sample of middle-aged women (N = 1447). We also examined longitudinal measurement invariance in a subsample of participants (n = 803) who responded to the survey 5 years later. The bifactor S-1 ESEM provided an excellent fit to the data and the factor loading pattern showed a well-defined global self-determination factor anchored in intrinsic motivation with decreasing contribution from the other items on the continuum. Relations between the global and specific motivation factors, food habits, binge eating, and BMI provided evidence of criterion-related validity. Longitudinal measurement invariance across time was also verified. Our results support the idea that the global factor represent a general quantity of self-determination rather than relative self-determination.