Body image, BMI, and physical activity in girls and boys aged 14–16 years

•Examined body image, body mass index, and physical activity in 3249 girls and boys.•More positive body image was associated with higher physical activity.•Positive body image is predictor of physical activity regardless of body mass index.

The aim of this study was to investigate the relationship between body image, body mass index (BMI), and physical activity in adolescents. The study included 1702 girls and 1547 boys aged 14–16 years. Moderate-to-vigorous physical activity (MVPA) was evaluated by the Physical Activity Screening Measure. Body image was assessed using the Feelings and Attitudes Towards the Body Scale, and participants’ BMI was determined based on measured height and weight. Compared to boys, girls reported more negative body image (p < .05). The results of the three-way hierarchical regression revealed that body image was a statistically significant positive predictor of MVPA for adolescents, regardless of BMI. Additionally, body image was a stronger predictor of MVPA in boys than in girls. These findings suggest that body image, rather than BMI, is important in undertaking physical activity in adolescents and should be considered when preparing programs aimed at improving physical activity.