Background. Bioimpedance analysis (BIA) is often used for the assessment of relative body fat (%BF). The accuracy of the test depends on prediction equation used, which respects the group of population, body composition, age and gender of the individual. The requirement to construct a specific prediction equation for obese population with more than 30% body fat was suggested. The objective of the study was to evaluate the validity of bioimpedance analysis and to develop population-specific prediction equation for obese women. Methods and Results. Relative body fat were measured in set of 63 obese women by means of 3 methods:t etrapolar bioimpedance analysis, bipedal bioimpedance analysis and dual energy X-ray absorbtiometry (DEXA). Significant differences were found among mean values of %BF measured by methods above (39,9%, 42,2% and 48,7%, respectively). Significant correlation between results obtained by tetrapolar BIA and by DEXA method was noticed (R=0,73). New specific prediction equation was developed for measuring %BF of obese women by tetrapolar BIA. No good agreement between bipedal BIA and DEXA method was found. Conclusions. By using the new prediction equation, measurement of the relative body fat in obese women by tetrapolar bioimpedance analysis was comparable with the reference DEXA method.

        Key words: bioimpedance analysis, prediction equation, body fat.