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

The 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 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.