The Mediating Role of Behavioural Regulations in the Relationship between Perceived Body Size Discrepancies and Physical Activity among Adult Women

Research has shown a negative relationship between perceived body size discrepancies and exercise participation among women. This might be explained from a selfdetermination theory perspective by perceived discrepancies between actual and ideal body size causing individuals to feel less autonomous in the regulation of their exercise behaviour. The aim of this study was to test the mediating role of exercise behavioural regulations in the relationship between body size discrepancies and physical activity participation. Participants were 102 women who completed measures of body size discrepancies, behavioural regulations and physical activity. Analyses showed that a reduction in more autonomous regulations mediated a negative relationship between discrepancies and physical activity. Less autonomous regulations did not play a mediating role. Thus it appears that body size discrepancies exert a negative influence on physical activity by decreasing feelings that exercise is a valued and enjoyable activity rather than by leading people to feel more externally or internally controlled in their behaviour.