Analysis accurately predicts fat-free mass in healthy Asian individuals with
varying body fat levels.
Bioelectrical Impedance Analysis (BIA) is a convenient and safe method in
predicting body composition. The result was published in 2015 issue of
Nutrition Journal, emanated from the study that used standing foot to foot BIA
for predicting fat-free mass (FFM) in healthy Asian population. The regression
model developed was tested for predicting FFM in people having differing body
fat percentages (BF %).
A study of 554
Taiwanese subjects (males: 297; females: 257; aged 16 to 75 years; mean: 32.8
▒14.8 years; mean weight: 39 to 125.5 kg and BMI 15.9 - 43.1kg/m2; mean BMI
24.0 ▒4.1 kg/m2)
were recruited in the study. The subjects were required to fill health
questionnaire that involved personal background information, physical
characteristics and health status. These subjects were tested for 48 hours
without alcohol, no diuretic agents for 7 days
and no strenuous physical activity for 24 hours. No testing for female subjects
was done during their menstruation cycle and no history of endocrine,
nutritional or growth disorders, chronic illness like blood pressure, liver
or electronic device insertion was reported.
During body measurement by using DXA (dual energy X-ray absorptiometry) system
any kind of metallic objects was removed. The body measurement included
measuring of total body fat
fat-free soft tissue and bone mineral content and foot to foot impedance was
done post DXA measurements. The BIA measurement was done using impedance
measurement device. The within day and between day estimates coefficient of
variation (CV) were calculated in all subjects.
The subjects were
divided into two groups G1 & G2 based on BF%. Root mean square error (RMSE)
and pure error (PE) was used for testing accuracy of FFM predictive model by
BIA. All analysis was done using SPSS for windows and Medcalc. Statistical
significance was set up to p<0.05 for all tests.
Results of the study
showed BMIs for G1 and G2 as 23.9▒4.1 kg/m2
(range 16.0-43.1) and
(range 16.2-42.9) respectively. The subjects were
also further subdivided into five different subgroups by 10% body fat
intervals. CV of within day and between day estimates of impedance in 10
subjects was 0.3%-0.8% and 0.9%-1.7% respectively. The correlation coefficients
of different BF% DXA
subgroups were seen from 0.89-0.94. Subgroups
(female: BF% DXA
> 40% and male: BF% DXA > 30%) showed largest
bias ▒ SD of FFM DXA
& FFM BIA
with bias ▒ SD of -2.0
▒ 2.9 kg and 2.1 ▒ 3.2 kg respectively. Subgroups showing smallest bias ▒ SD of
& FFM BIA
was female (bias ▒ SD 0.0 ▒ 3.0 kg)
and male (0.0 ▒ 3.2kg) respectively.
In addition, the study
also demonstrated that irrespective of standing or supine position, there was
only 1% reduction in the foot-to-foot impedance measurement that occurred over
a three minute period. Predictors of regression model were calculated on basis
of height 2
/impedance, sex, weight and age. The correlation
coefficient of FFMDXA
was 0.92, whereas standardized coefficient β
was 0.43. The prediction model that was developed using G1 and G2 data was
further validated using RMSE of 2.31kg (bias ▒ SD: -0.01 ▒ 3.22) and 2.18 kg
(bias ▒ SD: 0.05 ▒ 3.12) respectively.
In summary, no
significant difference was seen in the predictive value of FFM by using this
model from FFM DXA
among subgroups of different BF% values and
sexes. The correlation coefficient was 0.87 in females, whereas 0.89 in males.
The results showed that FFM predictive model based on BIA estimates is an
effective method to assess FFM in healthy subjects having different BF% values.
Further, FFM predictive model based on standing foot to foot can be
appropriately used to predict FFM in both males and females healthy Asian
subjects having different BF% values.
Wu et. al. Predicting body composition using foot-to-foot bioelectrical
impedance analysis in healthy Asian individuals. Nutrition Journal 2015, 14:52