Changes in BMI and the prevalence of overweight and obesity in children and adolescents (11-15 years) from Kraków (Poland) during COVID-19 pandemic.

In March 2020, the spread of the new coronavirus SARS-CoV-2, triggered a pandemic of acute respiratory distress syndrome among people. The aim of the study was to evaluate the changes in BMI and in the prevalence of overweight and obesity in children and adolescents (11-15-year-olds) from Kraków (Poland) during the COVID-19 pandemic. Two cross-sectional studies were performed in 2020 and 2022 in randomly selected elementary schools in 4 districts of Kraków. The study group was 1572 children between the ages of 11-15 years. BMI (Body Mass Index) was calculated. Participants were grouped using Cole's cut-off points. The statistical significance of differences between the groups was estimated using the two-way ANOVA and Chi² test. An increase in the prevalence of underweight and normal weight was observed in both sexes. In girls a decrease in the prevalence of obesity was noted, while in boys, the same tendency was present in some age groups. In girls, a decrease in the prevalence of overweight and in the average BMI was noted; in boys the trend was the opposite. The observed results may be correlated with changes in body composition and restrictions resulting from the lockdown caused by the COVID-19 pandemic.