GENDER DIFFERENCES IN FAT MASS OF 5-7-YEAR OLD CHILDREN

OBJECTIVE: Studying gender differences in fat mass and distribution in a homogeneous group of children. DESIGN: Crosssectional study. SUBJEC TS: 610 children aged 5-7 y in Kiel, Germany. METHODS: Anthropometric measures, bioelectrical impedance analysis (BIA). RESULTS: Although bo ys had increased body weights (P<0.05), body mass indexes (BMI's) (P<0 .001) and waist/hip ratios (WHRs) (P<0.001), the %fat mass as assessed by BIA (P<0.05) was increased in girls. Although the increased BMI in boys was independent of the percentile used, gender differences (that is, lower values for boys than for girls at the same age) in WHR, the sum of four skinfolds and %fat were seen up to the 90th percentile. B y contrast, above the 90th percentile there were no differences in ski nfold thickness and %fat between boys and girls. Studying 42 BMI-match ed pairs (boys and girls) also showed that the %fat estimated by BIA ( P<0.001) was increased in girls. Plotting the average of %fat as obtai ned from skinfold- and BAI-measurements against the difference between data obtained by the use of the two methods shows that BIA %fat overe stimates skinfold %fat at low or normal percent fat mass (that is, up to 20%) in both genders. By contrast, at increased fat mass, BIA %fat seems to underestimate skinfold %fat in both genders. CONCLUSIONS: Gen der differences in fat mass and fat distribution are obvious in childr en aged 5-7 y. These differences are independent of gender differences in body weight. However, the nutritional state has an influence and g ender differences cannot be detected in overweight and obese children. Our data also suggest that a children-specific formula used to calcul ate %fat from skinfold measurements is inappropriate.