Secular changes in body height, body mass, and BMI among rural boys in Eastern Poland (1986–2021)

INTRODUCTIONBody height, body mass, and BMI are key indicators of physical development, reflecting the combined effects of genetic potential and environmental conditions. Secular changes in these traits are particularly pronounced in populations undergoing socio-economic transformation, including rural regions. Eastern Poland remains one of the economically weakest regions of the European Union, which may influence the somatic development of children and adolescents.STUDY AIMThis study examined long-term secular changes in body height, body mass, and BMI among rural boys aged 7–15 years from eastern Poland between 1986 and 2021.MATERIAL AND METHODSThe sample comprised 14,685 boys from five cross-sectional surveys conducted in 1986, 1996, 2006, 2016, and 2021, with sample size increasing from 1,259 to 5,599. Measurements were performed using standardized anthropometric procedures, and BMI categories were defined using Cole’s international cut-off points. Statistical analyses included one-way ANOVA with Games–Howell post hoc tests, linear regression, and chi-square tests for BMI categories.RESULTSSignificant increases were observed in all traits. Between 1986 and 2021, mean body height increased by 7.85 cm, with the largest gains among 13-, 9-, and 14-year-olds. Mean body mass rose by 5.83 kg, particularly in 14- and 15-year-olds. BMI increased by 1.21 kg/m², with the greatest changes occurring in older boys. The prevalence of overweight and obesity increased consistently across all age groups, with a marked acceleration between 2016 and 2021, while the prevalence of underweight declined slightly over the long term. Regression models confirmed systematic upward trends in all somatic traits.CONCLUSIONSThese findings indicate that although linear growth continues, the pattern of development is increasingly characterized by rising body mass and BMI, reflecting a shift toward a higher prevalence of overweight and obesity. This trend highlights the need for targeted public health monitoring and early preventive strategies in rural populations.