Predictors of weight status in school-aged children: a prospective cohort study

BACKGROUND/OBJECTIVES: To prospectively investigate the predictors of overweight/obesity and of body mass index (BMI) change in schoolchildren. SUBJECTS/METHODS: A cohort of 2755 Irish children (53.7% girls), aged 6-10 years at baseline, participating in the Childhood Obesity Surveillance Initiative were included. Height and weight were objectively measured and BMI was calculated. Overweight/obesity were defined according to the International Obesity Task Force cut-offs. Prevalence of overweight/obesity at baseline and follow-up, incidence of overweight/obesity and changes in BMI over time were computed. Lifestyle indicators were parentally reported with a questionnaire. Predictors of overweight/obesity were investigated by multivariate mixed logistic regression models. RESULTS: Baseline BMI (OR = 6.46, 95% CI = 4.56-9.17) and school socioeconomic level (OR = 2.12, 95% CI = 1.16-3.86) were associated with higher risk of becoming overweight/obese. Children with no savoury snacks consumption (OR = 0.22, 95% CI = 0.07-0.69), or with frequent sports/dancing clubs attendance (OR = 0.41, 95% CI = 0.19-0.88) had lower odds of overweight/obesity at follow-up. Poor fruit intake was associated with higher risk of overweight/obesity (OR = 2.16, 95% CI = 1.23-3.78). CONCLUSIONS: Initial BMI was the main predictor of subsequent overweight/obesity in schoolchildren, followed, to a lesser extent, by school socioeconomic status. Although lifestyle behaviours appeared to have lower effect as compared with prior BMI, children with healthier lifestyle behaviours were at reduced risk of overweight/obesity at follow-up. Programmes that aim at preventing the onset of overweight and obesity need to be a priority given the existing difficulties to reverse this condition later in life.