Impact of school-based nutrition and physical activity intervention on body mass index eight years after cessation of randomized controlled trial (AVall study)

Abstract

Background & aims: The prevalence of obesity and overweight among children is increasing, representing a new and pressing societal problem. Excess weight in childhood is an independent risk factor for adult obesity. Although school-based interventions are generally considered effective in the short term, few studies analyze their longterm impact. The aim of study was to assess if the effect of the intervention on body mass Index (BMI) immediately after the intervention remained eight years later (AVall Study).

Methods: In 2006-2008, an intervention for primary school children promoted healthy eating habits and physical activity in the school setting using the Investigation, Vision, Action and Change (IVAC) educational methodology, which involves children as active participants in healthy change. At baseline, parents reported their weight, height and educational level by questionnaire. Children's weight and height were measured in situ in 2006, 2008, 2010, 2012 and 2016, and levels of physical activity were assessed by questionnaire. Multilevel mixed effects linear regression was used to assess changes in BMI over time.

Results: Increases in BMI from 2006 to 2016 were 0.68 kg/m² (95% CI, 0.02, 1.34; P = 0.045) higher in the control group than in the intervention group. The prevalence of obesity and overweight combined in 2006 and 2016 was 22.2% and 27.9%, respectively, in the control group and 25.6% and 21.2% respectively, in the intervention group. Changes in BMI in the intervention group were maintained from 2006 on: at the end of the intervention in 2008, -0.4 kg/m² (P = 0.001); in 2010, -0.23 g/m² (P = 0.012); in 2012, -0.63 kg/m² (P < 0.001) and in 2016, -0.27 kg/m² (P = 0.025). The child's BMI increased by 0.52 kg/m² (P = 0.046) if the father was obese, by 1.26 kg/m² (p = 0.011) if the mother was obese, and by 2.37 kg/m² (P < 0.001) if both parents were obese. Parental education levels were not associated with childhood obesity.

Conclusions: A school-based healthy eating habits and physical activity intervention using IVAC methodology contributed to lower increases in BMI among children in primary school. Although parental BMI also influenced children's BMI, the intervention was effective.

Trial registration: ClinicalTrials.gov NCT01156805.

Keywords: Children; Dietary habits; Obesity; Overweight; Physical activity.