To determine whether similar gender differences in body fat could be detected in prepubertal as in pubertal children, bioelectrical impendance measurement (BIA) was performed in 221 healthy children in Croatia. Height and weight were also measured and body mass index (BMI) was calculated. Two hundred and twenty one children (117 girls and 104 boys) aged 7-10 years (prepubertal) and 15-17 years (pubertal) were rcruited from local schools. Pubertal girls were at least 2 years postmenarchal, had regular menstrual cycles and Tanner stage 4 or 5. Pubertal boys had also Tanner stage 4 or 5. Detailed characteristics of studied children were presented on Table. Age Height Weight BMI Body fat (yrs.) (cm) (kg) (kg/m2) (%) Prepubertal girls (N=59) 8.6+/-0.9 137.5+/-7.9 32.6+/-6.8 17.2+/-2.5 24.7+/-5.4 Prepubertal boys (N=54) 8.6+/-1.0 137.1+/-7.3 33.1+/-8.1 17.5+/-3.1 18.3+/-7.8 Pubertal girls (N=58) 16.1+/-0.7 165.4+/-6.3 60.8+/-7.6 22.2+/-2.3 31.2+/-5.7 Pubertal boys (N=50) 16.2+/-0.6 178.7+/-5.9 72.1+/-9.4 32.6+/-2.9 16.2+/-6.9 Prepubertal girls and boys did not differ in anthropometric variables but girls had approximately 40% more body fat than boys what represents statistically significant difference (p<0.01). In pubertal children, significant differences were evident in all measured variables between boys and girls (p<0.01) except in BMI. Percentage of body fat was significantly greater (93%) in pubertal girls than in boys. Pubertal gisrls had approxamately 26% more body than prepubertal girls (p<0.01). Pubertal boys had less body fat (13%) than prepubertal boys but the difference was not significant. BMI was significantly greater in pubertal children, but without any differences between genders regardless of age. In conclusion, significant gender differences in body fatness are evident well before puberty and get even greater after the onset of puberty. BMI is not a reliable measure of body fatness in children.

Kliničke medicinske znanosti