Body image flexibility and exercise motivation: A two-sample replication study.

Body image flexibility - defined as one's ability to accept positive and negative body-related experiences - is theorized to promote adaptive motivational and behavioural outcomes. To date, there is a dearth of literature examining how body image flexibility is related to exercise motivation, a key predictor of exercise behaviour. The purpose of this study was to examine prospective within- and between-person associations between body image flexibility and autonomous and controlled exercise motivation in two independent samples. In Study 1 (N = 204) and Study 2 (N = 165), university students completed online surveys once a week for three weeks. Findings were consistent across studies, whereby during weeks when participants experienced higher than usual body image flexibility, they reported lower levels of controlled motivation (bs = -0.13 to -0.09, ps < .001). Further, participants with higher average levels of body image flexibility reported lower average scores of controlled motivation (bs = -0.30 to -0.27, ps< .001). Body image flexibility was not associated with autonomous motivation in either study. The findings provide novel insights on the relationship between body image flexibility and exercise motivation and identify body image flexibility as a potential modifiable factor that may be associated with lower controlled exercise motivation in daily life.