Central overweight and obesity in Polish schoolchildren aged 7-18 years: secular changes of waist circumference between 1966 and 2012

Abstract

We investigated secular trends of body mass index (BMI) and waist circumference (WC) in Polish schoolchildren examined through a period of almost 50 years. Data on height, weight and WC came from four cross-sectional surveys conducted in Poland between 1966 and 2012, covering 34,005 boys and 34,008 girls. Raw data of BMI and WC were standardized for age classes. Statistical analyses included the Kruskal-Willis test and Pearson Chi-square test. BMI and WC increased during the studied period; however, the growth was higher for WC (increase by 0.56 and 0.44 SD scores for BMI and 1.05 and 0.77 SD scores for WC in boys and girls, respectively). In boys, secular changes in BMI and WC were similar across childhood, early and late adolescence, while in girls they differed, indicating change in the type of adipose tissue distribution to a more central one in late adolescent girls.

Conclusion: During 46 years, there was a tendency to a greater increase of the fraction of individuals with central obesity than the overall one. Since abdominal fat deposit is more connected with higher health risks than subcutaneous fat pattern, probably the number of metabolic complications in Polish children and adolescents will intensify in the future. What is Known: • BMI has significant limitations related to fat distribution, while WC is a measure of central adiposity. • Greater central fat deposition increases the risk of many diseases; therefore, WC may serve as a diagnostic measure for detecting central obesity in children at risk. What is New: • In girls, changes in BMI and WC indicate change in adipose tissue distribution to a more central one in late adolescence girls. • Both general and abdominal obesity in Polish children increased significantly from 1966 to 2012, with the tendency to a greater increase of the fraction of individuals with central obesity than the overall one, implying the number of metabolic complications in Polish children and adolescents may intensify in the future.

Keywords: Central overweight; Obesity; Schoolchildren; Secular changes; Waist circumference.