BMI in the BMJ

Reilly et al entitle their article, “Physical activity to prevent obesity …” and conclude, “Alternative interventions [to physical activity] to prevent obesity in young children are required.”1 The emphasis on a lack of impact of physical activity on obesity is unfortunate for four reasons.

Firstly, the independent variable was not successfully manipulated: the intervention failed to generate differences in physical activity or sedentary behaviour between groups. Why would one expect a “physical activity intervention” which has no impact on physical activity to alter energy balance or “obesity”? …