Body-Shape Concerns, Eating Regulation, and Mediterranean Diet Adherence in a Romanian Convenience Sample: A Cross-Sectional Self-Determination Theory Perspective

Autonomous motivation may support healthy eating, whereas body-shape concerns may fuel controlled eating regulation; the two had not been examined jointly with Mediterranean diet adherence in Romanian adults. In this cross-sectional study, a convenience sample of 224 predominantly female (87.1%), university-educated Romanian adults completed the Body Shape Questionnaire-16B (BSQ-16B), the Regulation of Eating Behaviors Scale (REBS), and a Romanian-adapted 14-item Mediterranean Diet Adherence Screener (MEDAS). The theory-derived expectations were not preregistered. Fit of the six-factor REBS structure improved substantially when cross-loadings between adjacent regulations were allowed, though discriminant validity remained limited; a bifactor analysis supported the BSQ-16B total score. BSQ-16B scores were associated with introjected (β = 0.65) and controlled regulation (β = 0.54) but not with autonomous styles or adherence (ρ = −0.03). Autonomous motivation was associated with adherence after adjustment (b = 0.63 points per standard deviation; 95% confidence interval 0.31–0.94), as was physical activity; in an exploratory subscale model, integrated regulation showed the strongest unique association. Body-shape concerns were coupled with internal pressure but showed little evidence of an association with MEDAS-assessed adherence, whereas autonomous regulation emerged as a relevant correlate. The findings are consistent with, but do not test, autonomy-supportive counseling.