The Associations Between Self-Perceived Actual and Ideal Body Sizes and Physical Activity Among Early Adolescents

This study examined the association between self-perceived actual and ideal body sizes and objectively assessed moderate-to-vigorous physical activity (MVPA) among adolescents, controlling for puberty, fat mass index, and sex. A secondary objective was to explore the association between objectively assessed fat mass index and MVPA.

Participants were 438 early adolescents (Mage = 11.61, SD = 0.92). Participants selected body sizes that represented their self-perceived actual and ideal bodies. Participants then wore an accelerometer for 1 week to assess MVPA. Polynomial regression analysis with response surface methods was used to explore MVPA in relation to the discrepancy and agreement (ie, no discrepancy) between self-perceived actual and ideal body sizes.

When self-perceived actual and ideal body sizes were in agreement and represented smaller and larger bodies, MVPA was low. Participants with similar self-perceived actual and ideal bodies in the middle of the body-size spectrum demonstrated the highest levels of MVPA. The direction and degree of the discrepancy between self-perceived actual and ideal bodies were not significantly associated with MVPA. Fat mass index was significantly and negatively associated with MVPA.

These findings may inform physical activity promotion programs and provide methodological contributions to the study of how body image and MVPA are related.