Body fat and fat-free mass measured by bioelectric impedance spectroscopy and dual-energy X-ray absorptiometry in obese and non-obese adults

Abstract

The aim of the present study was to compare body fat mass (FM) and fat-free mass (FFM) estimates by bioelectric impedance spectroscopy (BIS), with respective estimates by dual-energy X-ray absorptiometry (DXA), in obese and non-obese subjects. Body composition was measured in ninety-three obese and non-obese men and women by BIS device, BodyScout (Fresenius Kabi, Bad Homburg, Germany) and DXA device, Lunar iDXA (GE Healthcare, Madison, WI, USA). Mean difference between the methods was analysed by t tests, and Bland-Altman plots were generated to further examine the differences between the methods. Mean difference between the estimates by DXA and BIS (D DXA2BIS and Bland -Altman 95 % limits of agreement) were as follows: FM 4·1 (2 2·9, 11·2) kg and 4·5 (2 2·9, 11·8) %, FFM 2 4·1 (2 11·2, 2·9) kg and 2 4·5 (211·9, 2·9) %, indicating large inter-individual variation and statistically significant underestimation of FM and overestimation of FFM by BIS, as compared to DXA. The underestimation of FMkg (FM measured in kg) and overestimation of FFMkg (FFM measured in kg) were more pronounced in men than in women, and the underestimation of FM% (FM measured in percent) and overestimation of FFM% (FFM measured in percent) were more pronounced in normal weight (BMI ¼ 20·0-24·9 kg/m 2 ) than in overweight and obese (BMI $25·0 kg/m 2 ) subjects. BIS may be suitable for classification of a population into groups according to FM and FFM. However, the large inter-individual variation suggests that this BIS device with the proprietary software is insufficient for estimation of single individual body FM and FFM.

Disparate Body Composition Outcomes for Underwater Weighing, Dual-Energy X-Ray Absorptiometry, and Two Bioelectrical Impedance Devices in Overweight Young Adults

“…While the SF-BIA was found to significantly underestimate %BF relative to mean DXA outcomes, SF-BIA results were significantly correlated with HW (p < 0.05, r = 0.902), lending credence to their veracity. This outcome builds agreement with other projects investigating BCA in obese individuals; these researchers, which have previously warned that DXA and SF-BIA devices cannot be used interchangeably in light of the additive variability encompassed by these methods [38][39][40].…”

Accumulating Data to Optimally Predict Obesity Treatment (ADOPT): Recommendations from the Biological Domain

“…BIS has also been reported to correlate better with FM than BMI and with visceral and/or intraabdominal fat (measured by MRI) than waist circumference or WHR . Overall, BIS has been reported to explain 80% to 90% of the variance in FM and visceral fat and 50% to 55% of the variance in intraabdominal fat by DXA and/or MRI . Despite the advantages of BIS, it has been reported to underestimate FM and overestimate FFM, especially in males , and BIS can be less reliable when the hydration status of FM and FFM are uncertain (e.g., in children, individuals with edema, and postbariatric surgery patients).…”

“…Overall, BIS has been reported to explain 80% to 90% of the variance in FM and visceral fat and 50% to 55% of the variance in intraabdominal fat by DXA and/or MRI . Despite the advantages of BIS, it has been reported to underestimate FM and overestimate FFM, especially in males , and BIS can be less reliable when the hydration status of FM and FFM are uncertain (e.g., in children, individuals with edema, and postbariatric surgery patients). In addition, there are multiple BIS systems available that have not been crossvalidated.…”

“…During dynamic periods of weight change (EI ≠ EE), measuring EI is more difficult. Self‐reported EI measures have been shown to be inaccurate but changes in EI (recommended) during such periods can be mathematically modeled with measures of EE and body composition dynamics . This model has recently been validated against the intake‐balance method in a 2‐year calorie‐restriction experiment in 140 people of varying age and BMI , and it requires only baseline anthropometric and demographic information along with repeated body weight measurements over the course of the intervention.…”

Application of bioelectrical impedance to sports science

“…This method was used by Lukaski et al 24) and Baumgartner et al 25) to estimate FFM and %FAT. Several studies revealed that FFM or %FAT could also be accurately predicted in various people using the BIA methods 26) . Additionally, with multi-frequency BIA, it is possible to estimate extracellular water and intracellular water compartments, along with TBW.…”