ABSTRACT
BACKGROUND: Neck circumference (NC) has been proposed as an indicator of upper trunk adiposity and a potential indicator of metabolic risk. The objective was to evaluate NC and its correlation with body fat percentage (BF%) and other indicators of adiposity in children with normal weight, overweight, and obesity. METHODS: In a cross-sectional study, 112 children 5 to 10 years of age were included in the outpatient clinic from a public hospital. Measures of weight and height to calculate BMI (kg/m2), NC, mid-upper arm circumference, waist circumference, and tricipital skinfold thickness. Body composition measurements were performed using an electrical bioimpedance device (BIA). The relationship between anthropometric variables and BF% obtained by BIA was determined using Spearman correlation tests. Multivariate models were constructed with BF% as the dependent variable and anthropometric parameters as independent. RESULTS: In the entire group, there was a direct correlation between NC and BF% (r = 0.50, p < 0.001), but lost statistical significance in the case of normal weight. The relationship maintained its significance in subjects from the overweight and obesity groups. In multivariate models, BMI exhibited the highest correlation with BF%, followed by waist circumference and mid-upper arm circumference; for NC, the R2 value was 0.30 (p < 0.001). CONCLUSIONS: Neck circumference is useful in the screening of population groups with the advantage of not requiring any specialized instruments for its measurement other than a tape measure. BMI and waist circumference were the best indicators of general and central adiposity, respectively.
ABSTRACT
BACKGROUND: There is a possibility that excess body fat affects bone mass gain and may compromise skeletal health in obese children. The purpose of the study was to identify the relationship between bone mineral density (BMD) and body composition in normal weight, overweight and obese children. METHODS: This was a cross-sectional study of 6- to 11-year-old children who attended the hospital's outpatient clinic. They were apparently healthy and had no history of prematurity, low birth weight, or chronic diseases. Body mass index (BMI) was used to identify subjects as normal weight, overweight or obese. BMD and body composition were assessed by dual energy X-ray absorptiometry. The BMD values (total and lumbar spine) were compared between normal weight, overweight and obese children. Correlation coefficients were calculated, and multivariate models were performed. RESULTS: Forty-nine children were included: 16 with normal weight, 15 that were overweight and 18 with obesity; the mean age was 8.4 ± 1.7 years. All the participants had a normal BMD (> - 2 SD). BMD was higher in obese children and had a positive correlation with total and trunk lean mass in the three study groups (p < 0.001). In obese children, an inverse correlation of lumbar spine BMD (Z score) with total and trunk fat mass (p < 0.05) was identified. In the multivariate models (with the whole group), the total lean mass was the only significant variable that explained BMD variability. CONCLUSIONS: BMD in obese children was higher than that in normal weight children, which is explained by their greater lean mass and not by excess body fat. In obese children, a higher fat mass was related to a lower lumbar spine BMD. Lean mass had a direct correlation with BMD in the three study groups and was the most important predictor of BMD, reflecting the importance of strengthening the muscular system through performing physical activity and practicing a healthy lifestyle.