Parental TV-viewing time was associated with Portuguese children's TV-viewing time. The numbers of TVs in the household and electronic games equipment access were also associated with TV- and combined other media-viewing/usage time.

Objectives Childhood obesity is a public health concern in Portugal. Socio‐demographic and behavioral factors are highly associated with obesity but are not clearly understood. This article aims to update the prevalence of overweight and obesity in Portuguese children and to explore the influence and risks of socio‐demographic factors and behavioral factors. Methods A cross‐sectional study of Portuguese children aged 3–10 years from all 18 mainland districts took place between March 2009 and January 2010. The sample was composed by 17,136 children, 3–10 years of age (8,455 boys; 8,681 girls). Height, weight, and other anthropometric measurements were obtained by trained technicians. Body mass index (BMI) was calculated along with other anthropometric variables. Data analyses took place between April and September 2012. The overweight/obesity classification was established by age‐and sex‐specific BMI cut‐off points as defined by the International obesity task force (IOTF). Parents completed questionnaires about socio‐demographic and behavioral characteristics of the family. Results Almost 28% of the Portuguese children were overweight or obese (19.7% overweight; 8.2% obese). Prevalence was greater in girls than in boys. Logistic regression models found that the odds of childhood obesity were significantly affected by biological, socio‐demographic, and behavioral factors. Conclusions The protective factors against childhood overweight/obesity in this sample of Portuguese children are: (i) being male; (ii) having been breastfeed; (iii) having been born from mothers who did not smoke during pregnancy; (iv) engaging in little sedentary behaviors (TV, PC, and playing electronic games); (iv) performing at least 1 h of moderate physical activity every day; and (v) having parents with higher educational levels who also have their BMI within the healthy ranges. Am. J. Hum. Biol. 25:733–742, 2013. © 2013 Wiley Periodicals, Inc.