Changes in height, weight, BMI and in the prevalence of obesity among 9-to 11-year-old affluent Portuguese schoolboys, between 1960 and 2000

Background: There is a lack of detailed series of growth data that can be used to analyse secular trends in growth and obesity of Portuguese children. Aim: The purpose of this study was to examine the secular trend in height, weight, BMI and in the prevalence of obesity (including overweight), during the last four decades, in a sample of high socio-economic status Portuguese boys. Subjects and methods: All candidates (9-11 years) to a military boarding school (Colegio Militar) in Lisbon, Portugal, examined between 1962 and 2006 were the subjects of this study. Records of height and weight measured during medical examination were obtained (n=3176). Body mass index (kg m-2) (BMI) was calculated and the International Obesity Taskforce (IOTF) cut-offs were used to define overweight and obesity. Results: The data obtained provide evidence for accelerating rates of overweight and obesity in affluent Portuguese boys, concomitant with a greater secular increase in mean weight, compared to that of height. Obesity (including overweight) more than doubled in the group of 9-year-olds (highest prevalence of 47.3% in 2000) and tripled in the group of 10- and 11-year-olds with greatest changes occurring between 1990 and 2000. Conclusion: The results suggest that a high family income does not necessarily translate into more informed choices about healthy foods and lifestyles, with a strong influence in the prevalence of obesity. This pattern of association between socio-economic status and obesity may reflect a late socio-economic transition of Portugal, compared to that of other high-income countries.