Quantitative assessment of infant body fat by anthropometry and total-body electrical conductivity.

Measurement of total-body electrical conductivity (TOBEC) has emerged as a rapid, safe, and reproducible method for estimation of infant total body fat (TBF). Agreement of two anthropometric methods [by Dauncey et al (1977) and Weststrate et al (1989)] with TOBEC-TBF was assessed in 435 healthy infants aged 21-365 d. Dauncey-TBF correlated with TOBEC-TBF by r2 = 0.61 and exceeded TOBEC-TBF by 0.14 +/- 0.25 kg in infants < 4 mo of age. Thereafter, TOBEC-TBF exceeded Dauncey-TBF by 0.20 +/- 0.47 kg. We modified Dauncey's method, which significantly improved the correlation to r2 = 0.75. Weststrate-TBF correlated with TOBEC-TBF by r2 = 0.87, but exceeded TOBEC-TBF by 0.5 kg. Both methods showed poor agreement with TOBEC-TBF. We conclude that both methods, although suitable for comparison of TBF between groups, cannot be used to accurately assess TBF in an individual infant.