Different techniques for body composition assessment

Abstract

The inter-relationships and alter nativity of body composition variables derived from simple anthropometry [BMI and Skin Folds (SFs) prediction equations] and Bioelectrical Impedance Analysis (BIA) with dual energy x-ray (DXA) of healthy sixty nine children (37 boys and 32 girls) aged 9.24±1.73 years old were evaluated. The children recruited from public schools in Giza governorate. All of them had BMI ranged between 15th and 85th percentile and were assessed for body composition [percentage body fat (%BF), fat free mass (FFM; kilograms) and body fat mass (BFM; kilograms)] using Slaughter Skin Folds (SFs) prediction equations, BIA and DXA. Repeated ANOVA showed significant differences among the three methods used for the studied variables (p<0.001). In general, Slaughter and BIA are significantly underestimated measured %BF. There is a high correlation between the BMI and both the estimated %BF and BFM (r = 0.67-0.91 for boys and r = 0.87 to 0.97 for the girls). Partial correlation among the estimated % BF derived from the three different methods in both genders revealed a high significant correlations between the estimated %BF derived from DXA and Slaughter equations (r = 0.76 for boys and 0.97 for girls). While the correlation between the estimated %BF derived from DXA and BIA was 0.77 for boys in contrast to girls where it is low significant correlation (r = 0.387). Results suggest that BIA has limited utility in estimating body composition, where as BMI and SFs seem to be more useful in estimating body composition. In conclusion all methods are significantly under estimated body fatness as determined by DXA and the various methods are not interchangeable.