Accuracy in Percent Body Fat from Skinfold Prediction Equations Vary Among Young, Middle-Age, and Older Male and Female Caucasians

Skinfold prediction equations (SF-PE) are used to estimate percent body fat (%BF), but it's unclear which SF-PE are most accurate among different age/sex groups. The purpose was to assess accuracy of estimating %BF from SF-PE in young, middle-age, and older male and female adults, and compare %BF from SF-PE to Inbody770 (IB770), a selected bioelectrical-impedance criterion reference. Two hundred two healthy males (n=96) and females (n=106) had %BF assessed from 12 SF-PE for females, 13 SF-PE for males, and IB770. Repeated measures 1-way ANOVAs (p < 0.01) were employed for three age groups for both males and females, and Bland-Altman plots were employed to evaluate the agreement between IB770 and SF-PE. Based both on statistical assessment and the Bland-Altman plots, similarity, agreement, and accuracy observed in %BF between IB770 and SF-PE were determined. From these assessments and plots, the following SF-PE are recommended to estimate %BF in young males (YM), middle-age males (MM), older males (OM), young females (YF), middle-age females (MF), and older females (OF) (%BF between IB770 and SF-PE shown): 1) YM: IB770 = 16.2%; Durnin 1974 (DW) = 16.3%; Williams 1992 (W) = 16.2%; Lean 1996 (L) = 16.6% ; 2) MM: IB770 = 19.7%; W = 19.7%; DW = 22.3%; 3) OM: IB770 = 24.4%; DW = 25.3%; W = 22.4%; 4) YF: IB770 = 24.9%; Jackson 1985 (JP3b) = 23.8%; 5) MF: IB770 = 25.2%; Jackson 1980 = 25.0%; JP3b = 26.1%; and 6) OF: IB770 = 36.6%; Peterson 2003 = 36.2%. Given that SF-PE either underestimated, overestimated, or accurately estimated %BF compared to IB770, this emphasizes the importance of using SF-PE that are appropriate for different age/sex groups and provide as accurate as possible estimates of %BF. Assessing %BF accurately is important given excessive %BF increases cardiometabolic disease risk.