Does health education affect BMI? Evidence from a school-based randomised-control trial.

We examine the effects of a comprehensive school-based health education programme (introducing healthy habits in the curriculum) to combat childhood obesity in the mid-size urban city of Granollers (Catalonia, Spain). The intervention was carried out between 2006 and 2008. New anthropometric measurements were obtained in 2008, 2010 and 2012. The length of the intervention evaluation constitutes a valuable contribution to the existing literature. Data refers to 509 schoolchildren aged 6 years old from 16 schools that were randomly assigned to either the intervention group or to the control group. Our results indicate that children's BMI in the treatment group was reduced by 1.13 kg/m(2) four years after the intervention, representing on average and for an average height, a loss of 1.6 kg. We examine heterogeneity and find that most effect is driven by children coming from disadvantaged backgrounds whilst no differences were obtained differentiating by gender.