Validation of Bioelectric Impedance Analysis for the Assessment of Body Composition in Young Adult Thai Women

Abstract

Obesity imposes high risks of metabolic diseases that become a major health concern in many countries. An accurate assessment of body composition is, therefore, required in the evaluation of body fatness of the population and hence in preventing the diseases. Bioelectric impedance analysis (BIA) has great potential in the assessment of body composition of population in field studies. However, BIA is sex, age, and ethnic specific. Currently, a prediction equation for Thais is still not available. In addition, the influences of alterations in body fluids during menstrual cycle in women on BIA are in controversy. This study attempted to establish a BIA equation for young adult Thai women (age 18-29 years) using the body density determined by an underwater weighing as a criterion method and to re-evaluate the effect of menstruation on BIA. Results showed that BIA values were not significantly changed in different phases of menstrual cycle. For the women with percentage body fat (%BF) less than 30%, Lohman’s equation for BIA of the women at the same age range was acceptable. On the other hand, body weight and resistance were the main attributes of BIA for overweight and obese women with %BF greater than 30%. A prediction BIA equation for this population is fat-free mass = 0.61 body weight - 0.003 resistance + 0.66. The coefficient of correlation (r), multiple regression (R²), and standard error of estimate (SEE) are, respectively, 0.98, 0.97, and 0.92.