RESUMO
BACKGROUND: In 2012, the prevalence of obesity and overweight statuses among children in Spain was 9% and 26%, respectively. Concerns about childhood obesity have increased over the past few years, as obesity developed during childhood can persist throughout an individual's lifetime (cohort effect). This study aims to develop a better understanding of the factors influencing the prevalence of obesity in Spain. METHODS: Microdata from the 2012 National Health Survey are used, and the methodological framework is based on the estimation of a sample selection model. RESULTS: Results suggest that the prevalence of obesity increases among children who live in households of a lower socio-economic status and households in which parents are obese. Lower levels of childhood physical activity are positively related to the probability of being obese. Finally, there exists a positive relationship between children's body mass index and an inappropriate intake of fresh fruits, fish, pasta and rice, legumes, sweets and soft drinks. CONCLUSIONS: The methodological framework used in this study is flexible enough to be used in traditional longitudinal studies. Children's and households' lifestyles play a pivotal role in the prevalence of obesity. Policies should be oriented toward changing lifestyles, which would require more multidisciplinary research in the future to reduce childhood obesity.