Physical activity to prevent obesity in young children: [1]

Reilly et al entitle their article, "Physical activity to prevent obesity â[euro]¦" 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"?

Secondly, the principal outcome measure, body mass index (BMI), is an inappropriate measure of obesity for two reasons.

Studies of obesity should focus on body composition, rather than measures of body weight (BMI). We, like Reilly et al, observed no differences in weight or BMI in supervised...