Abstract
BACKGROUND: This study investigates how motivational regulation mediates the relationship between body image satisfaction and physical activity participation, considering sex differences. METHODS: The study used a cross-sectional design and involved 1012 participants stratified by sex of the Spanish adult population. Body image satisfaction was assessed using the Multidimensional Body Self-Relations Questionnaire (MBSRQ), motivational regulation using the Behavioural Regulation Exercise Questionnaire (BREQ-3), and total weekly minutes of moderate-vigorous PA with the International Physical Activity Questionnaire Short Form (IPAQ-SF). Structural equation modelling was used to test the hypothesised relationships. RESULTS: The findings showed that satisfaction with physical appearance and physical shape had both direct and indirect associations with moderate-vigorous PA and motivational regulation. The relationship between body image satisfaction and moderate-vigorous PA was mainly mediated by intrinsic, integrated, and introjected regulations for men and integrated, identified, and amotivated regulations for women. CONCLUSION: These findings suggest that motivational regulation may play a crucial role in the relationship between body image satisfaction and PA participation. Promoting intrinsic and integrated motivation in men and women, respectively, rather than appearance-based goals, may foster more sustainable PA. The findings can provide valuable insights for policymakers and practitioners seeking to promote healthy PA behaviour. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40359-025-03476-4.