Differences in calculated body fat percentage estimated from published equations based on bioelectric impedance analysis in healthy young South African adults

Abstract

Adult overweight and obesity, in addition to the intake of saturated fat and total serum cholesterol mustbe monitored as biological risk factors for non-communicable diseases (NCDs). Bioelectric impedance analysis (BIA)provides data on body fat for use in epidemiological settings. However, optimized equations should be used to calculatepercentage body fat (%BF). The purpose of this study was to assess the differences between %BF calculated usingdifferent published BIA equations and %BF measured by BIA in young South African adults.Design and methods: In this observational study, differences in calculated %BF were assessed, with different BIAequations retrieved from the literature used in 1128 healthy young adults aged 20-30 years. The %BF (measured by BIA)was compared between equations, between Black and White men and women, respectively.Results: The results showed statistically significant differences in the %BF calculated from published BIA equations whenused in young South African adults (χ² = 946, χ² = 2528, χ² = 2088, respectively, p < 0.0001). In Black and White men andwomen, respectively, %BF levels were significantly higher when calculated by equations, than when measured by BIA(p < 0.0001).Conclusion: There seem to be large discrepancies in estimating %BF by BIA equations and these values cannot be usedinterchangeably for young South African adults. A South African age, ethnicity and sex-specific BIA equation needs to bedeveloped to accurately estimate %BF in young South African adults