Behavior of a New Equation using Bio- Impedancemetry to Predict Body Fat in Chilean Adults

Abstract

SummaryThe electrical Bioimpedance (BIA) methodology to determine body fat percentage (% FM) uses prediction equations developed in specific populations; which when applied in a population other than the one that have been generated, show an inaccurate behavior and its validity is questionable. The objective of this research was to analyze the behavior of a new equation to predict body fat mass from Bioimpedance in Chilean adults over a wide range of age and body mass index [1]. A cross-sectional analytical study was carried out on adult volunteers of sexes, aged 18-64 years and BMI of 18.5-34.9 kg/ m2. The % FM was estimated using BODYSTAT -QuadScan 4000 multifrequency BIA equipment; which was compared with the % FM determined by the new equation, through the statistical analyzes of Student's t and Pearson's R. Statistical tests indicate that there are no significant differences in the% FM estimated by both methods. The average body fat estimated by the formula inserted in the BIA equipment was 26.09 ± 8.84 % FM and the average when using the new formula of 25.89 ± 8.21 % FM. Nevertheless; the formula inserted in the electrical bioimpedance equipment would tend to overestimate the percentage of body fat in male subjects and to underestimate it in females. It is indispensable to submit the equation of Schifferli and collaborators to a validation process in an independent sample, in order to definitively determine its behavior against the reference method used in its formulation. This research can only suggest differences in fat estimation with respect to a BIA equipment currently available in the market.

Agreement and bias in the estimation of fat free mass using bioelectrical impedance analysis and a resistance and reactance- based formula for the Mexican adults: A study from Merida, Yucatan

“…The previous study (Schifferli et al 2011) developed prediction equation for BIA-based FFM, taking DEXA as the criterion or reference method. BIA overestimated PBF in men and underestimated in women compared to the corresponding values obtained using the prediction formula (Schifferli Castro and Zuniga 2017). Therefore, it is evident that BIA-based estimates of FFM may be different in men and women and vary with the levels of BMI and body fatness.…”

“…They also reviewed the literature to justify that ADP was a reliable and valid method and as good as hydrostatic weighing for the evaluation of body composition characteristics. Till date, the prediction formula developed by Macias et al ( 2007) is a reliable one that is available in Mexico to estimate FFM of adult individuals from the resistance and reactance values obtained through BIA and the article has been cited by many authors stating the usefulness of the formula (Balas-Nakash et al 2010;Caicedo-Eraso et al 2019;Lu et al 2016;Mbada et al 2015;Schifferli et al 2011;Schifferli Castro and Zuniga 2017;Wada and Tekin 2007). This raised my interest to use the same formula for Mexican adults (Macias et al 2007) and to find the agreement and bias between the estimated values of FFM (BIA-based and resistance and reactance-based) in a sample of adults from Merida, Yucatan, Mexico.…”