Bioelectrical impedance measurements at various frequencies to estimate human body compositions

Bioelectrical impedance analyses (BIA) operating at various frequencies were used to estimate body composition parameters and compared with the biochemically determined parameters by using isotopic dilution method in 22 healthy adult (30-50 years old) male human subjects. BIA instruments, operating at 50,100 KHz and 5 to 500 KHz range, were used to measure body compositions, namely total body water (TBW), fat free mass (FFM), and fat mass (FM). TBW of these subjects was also determined by deuterium dilution method. BIA methods measured at 100 KHz and using multifrequencies appear to be more accurate than at 50 KHz when compared with isotopic dilution method as standard. This accuracy could be attributed due to measurements made at higher frequencies that falls in the region where current passes through both extra- and intracellularly, thereby giving an appropriate measure of TBW. All the subjects participated in this study belong socioeconomically to the middle class and do not apparently look obese or fatty. However, the mean of their body fat, as estimated by the standard deuterium dilution method, was about 30% which is suggestive of an unapparent obesity prevailing in this class of people in Bangladesh.