Bioelectrical Impedance Analysis accurately predicts fat-free mass in healthy Asian individuals with varying body fat levels.
Standing foot-to-foot 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 %).
AdvertisementA 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 disease, asthma 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 24.0±4.1 kg/m2 (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 DXA & 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.
Reference:Shien Wu et. al. Predicting body composition using foot-to-foot bioelectrical impedance analysis in healthy Asian individuals. Nutrition Journal 2015, 14:52