Secular trends in underweight, overweight, and physical fitness of girls and boys aged 16–18 in eastern Poland from 2006 to 2016–2021

Introduction: Significant changes in the nutrition and physical fitness of children and adolescents have been observed in many countries around the world. The purpose of this study is to determine the changes in the prevalence of underweight, normal BMI, and overweight, as well as in the physical fitness of girls and boys from eastern Poland. Materials and methods: The study was conducted over the years 2006–2021. BMI was calculated, and physical fitness was assessed using the EUROFIT test. The results were statistically analyzed. Results: Minor changes in underweight were observed, and even a re-duction in its prevalence among girls was noted. However, a significant increase in the frequency of overweight was identified. Meanwhile, a decrease in the level of physical fitness in both girls and boys was recorded. These changes, however, were not uniform across all fitness abilities. Conclusions: The systematic decline in physical fitness among the examined girls and boys, particularly in cardiovascular-respiratory endurance, underscores the necessity for continued regular monitoring of the health of children and adolescents.