Changes of BMI and Fat Mass and Nutritional Behaviors in Children Between 10 and 14 Years of Age

Background/Objectives: Unhealthy nutritional behaviors and excess body weight constitute a serious challenge for public health in children and adolescents. The aim of this study was to examine changes in body mass index (BMI), body fat mass (FM) and nutritional behaviors in the same group of children during a 4-year observation between 10th and 14th years of age. Methods: BMI and FM using bioelectrical impedance were assessed. To assess nutritional behavior, a questionnaire was used. The study was done in the group of 250 children, starting from the age of 10 and finishing at the age of 14. The measurements were done in the year 2017 and 2021. The results were compared and analysed. Results: The excessive BMI (overweight and obesity) was more often in girls (28.29%) than boys (23.63%), while normal body weight was more often in boys (65.76%) than girls (60.96%). Between the initial and final assessment, percentage of children with normal body mass decreased from 65.65% to 61.07%. Excessive BMI (overweight and obesity) increased from 27.09% to 29.50% in girls, and from 21.26% to 26.00% in boys. The mean percentage of FM was higher in girls than boys (23.17% vs. 16.20%, respectively). The mean FM decreased from 17.80% to 14.60% in boys and increased from 21.77% to 24.57% in girls. The poor nutritional behaviors were observed in 20.35% of children, more often in boys (22.25%) than girls (18.50%). Between the initial and final assessment, an increase in the mean consumption of fruit, whole grain bread, milk was noted. These were products that should be consumed more often in a healthy diet. However, the consumption of products that should be limited in a healthy diet as fried flour dishes, fried meat dishes, fatty cheeses, butter, fast food, sweets, and carbonated drinks, also increased. Boys more often than girls consumed red meat and poultry meat, eggs, butter, and fast food while girls more often than boys consumed fruit, vegetables, yoghurts, cottage cheese, wholemeal bread, fruit, and sweets. Conclusions: Children usually showed moderate nutritional behavior. With age, in the evaluated group unfavorable nutritional behaviors and excessive body weight share increased. A higher overweight and obesity share and a higher body fat content were more often in girls than boys. Although girls’ nutritional behaviors were more healthy, they were at a higher risk of excessive body weight. Increasing the promotion of healthy nutritional behaviors and elevated physical activity to decrease overweight and obesity in children and adolescents is highly recommended.