New Skinfold-thickness Equation for Predicting Percentage Body Fat in Chinese Obese Children

Objective: To validate existing skinfold thickness predicting equations and to develop an equation for estimating body fat composition in obese Chinese children. Design: Cross-sectional study. Subjects: One hundred and thirty-eight Chinese obese children, 37 girls and 101 boys with mean age and body mass index (BMI) of 11.9 years (SD 2.7) and 29.7 Kg/m(2) (SD 4.8) respectively, referred for medical assessment were recruited. Measurements and methods: All subjects underwent physical examination and anthropometric measurement. Total percentage of body fat (%FM) was measured by dual-energy X-ray absorptiometry (DEXA) scan (%FM-DEXA). Three skinfold-thickness predicting equations for estimating %FM (%FM-SF) were compared with the measured %FM-DEXA. Results: The mean male and female percentage body fat measured by DEXA were 36.6% (SD 6.8) and 39.0%, (SD 4.2) respectively. There was significant gender difference in %FM-DEXA (p=0.05). The Durnin & Rahaman equation (%FM-DR-SF) best predicted %FM in,iris with a mean difference of %FM-DEXA-DR-SF of 0.76% (SD 4.0) but overestimated %FM in boys with a mean difference of -1.01% (SD 5.7). Lohman equation was the best in estimating %FM in boys. The mean differences of %FM-DEXA-L-SF were -0.94% (SD 5.62) and -2.58%, (SD 4.5) for boys and girls respectively. The gender difference as documented by DEXA was only demonstrated by the Lohman equation. Slaughter equation overestimated %FM in both genders. The mean differences %FM-DEXA-Sla-SF was -8.1% (SD 8.6%) in boys and -5.2% (SD 5.28%) in girls. A new predicting equation was derived for local use. Conclusion: Existing equations are inaccurate in estimating percentage of body fat in obese Chinese children. A specific equation based oil skinfold thickness was derived for estimation of %FM in obese Chinese children.