Article

Proportional Bias between Dual-Energy X-ray Absorptiometry and Bioelectrical Impedance Analysis Varies Based on Sex in Active Adults Consuming High- and Low-Carbohydrate Diets

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Abstract

Dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) are common methods of body composition assessment, but the agreement between these methods varies. Bias between DXA and single-frequency BIA was evaluated at six different time points in 48 active male and female adults consuming standardized high- and low-carbohydrate diets. It was hypothesized that fixed and proportional biases exist between DXA and BIA, but that the extent of bias does not differ based on sex. Substantial fixed bias was present for estimates obtained by DXA and BIA, and both males and females exhibited proportional bias for fat mass and fat-free mass. The magnitude of bias was greater in females, and only females exhibited proportional bias for body fat percentage. In individuals with less fat mass, the mean difference between DXA and BIA was high, indicating that BIA underestimated fat mass relative to DXA. However, in individuals with greater fat mass, better agreement was seen. Correspondingly, the mean difference in fat-free mass estimates was greater in individuals with less fat-free mass. In some individuals with high quantities of fat mass or fat-free mass relative to the sample, the relationship between devices was reversed such that BIA overestimated fat mass and underestimated fat-free mass. The degree of disagreement between DXA and BIA varies substantially based on body size and sex such that all-encompassing statements regarding the comparability of these technologies cannot presently be made.

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... A survey of sarcopenia among 694 hospitalized patients reported rates of 45.9% and 36.7% for men and women, respectively [18], which are considerably higher than that detected in our study (8.7% and 11.3%). The large difference in rates between the studies is likely due to the different methods of muscle mass measurement. ...
... The large difference in rates between the studies is likely due to the different methods of muscle mass measurement. In the current study, bioimpedance analysis was used to measure muscle mass, while the previous study [18] used dual X-ray absorptiometry. These techniques differ significantly in consistency of results[19]. ...
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Background: Sarcopenia is an age-related decline in skeletal muscle mass, which depends on an assessment of muscle strength and muscle mass. It has been reported that the prevalence of sarcopenia in non-hospitalized elderly people was 9.0%-18.5% in the lowland plains. However, epidemiological investigations of sarcopenia in plateau regions are limited. The city of Xining in Qinghai Province (altitude 2260 m) is the sole point of access to the Qinghai-Tibet plateau. We hypothesized that the diverse ethnicities or dietary habits of the people living in the plateau may influence the prevalence of sarcopenia. Aim: To investigate the prevalence and risk factors of sarcopenia in geriatric patients from the Qinghai-Tibet plateau region. Methods: From October to December 2018, 150 hospitalized geriatric patients (72.4 ± 5.60 years) from Xining City (altitude 2260 m) in Qinghai Province were recruited. Collected data included demographics, history of fall, nutritional status, self-care ability, depression, handgrip, muscle mass, and 6-m gait speed. Sarcopenia was diagnosed based on the 2014 criteria of the Asian Working Group for Sarcopenia. Results: The overall rate of sarcopenia was 20% (8.7 and 11.3% in men and women, respectively). Binary logistic regression analysis indicated that widowhood and a history of falling were associated with sarcopenia, while higher body mass index and beef and mutton consumption were protective. Conclusion: The prevalence of sarcopenia in hospitalized geriatric patients in the Qinghai-Tibet plateau region was higher than that in the plain region and in non-hospitalized geriatric people (reported elsewhere). Specific cultural features of the region, including ethnicity, brewed tea and ghee consumption, were not significantly associated with sarcopenia. Higher body mass index and consumption of beef and mutton were protective, while patients who were widowed or with a history of falling were at increased risk.
... Prior investigations of potential sex-based differences in the agreement between DXA and BIA have yielded inconsistent results (13,15,19). In the present investigation, an influence of sex on the agreement between DXA and BIA was demonstrated for FM TOTAL only. ...
... In the present investigation, an influence of sex on the agreement between DXA and BIA was demonstrated for FM TOTAL only. The agreement of DXA and BIA has been examined in participants of varying ages (9À16, 19,69), although limited data are available concerning age-related differences in agreement. In the present investigation, age was a potentially meaningful predictor for only 3 body composition outcomes (FM LEGS , LST LEGS , and FM TRUNK ). ...
Article
Introduction/Background Few investigations have sought to explain discrepancies between dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) body composition estimates. The purpose of this analysis was to explore physiological and anthropometric predictors of discrepancies between DXA and BIA total and segmental body composition estimates. Methodology Assessments via DXA (GE® Lunar Prodigy) and single-frequency BIA (RJL Systems® Quantum V) were performed in 179 adults (103 F, 76 M, age: 33.6 ± 15.3 y; BMI: 24.9 ± 4.3 kg/m²). Potential predictor variables for differences between DXA and BIA total and segmental fat mass (FM) and lean soft tissue (LST) estimates were obtained from demographics and laboratory techniques, including DXA, BIA, bioimpedance spectroscopy, air displacement plethysmography, and 3-dimensional optical scanning. To determine meaningful predictors, Bayesian robust regression models were fit using a t-distribution and regularized hierarchical shrinkage “horseshoe” prior. Standardized model coefficients (β) were generated, and leave-one-out cross validation (LOO) was used to assess model predictive performance. Results LST hydration (i.e., total body water:LST) was a predictor of discrepancies in all FM and LST variables (|β|:0.20-0.82). Additionally, extracellular fluid percentage was a predictor for nearly all outcomes (|β|:0.19-0.40). Height influenced the agreement between whole-body estimates (|β|:0.74-0.77), while the mass, length, and composition of body segments were predictors for segmental LST estimates (|β|:0.23-3.04). Predictors of segmental FM errors were less consistent. Select sex-, race-, or age-based differences between methods were observed. The accuracy of whole-body models was superior to segmental models (LOO-adjusted R² of 0.83-0.85 for FMTOTAL and LSTTOTAL vs. 0.20-0.76 for segmental estimates). For segmental models, predictive performance decreased in the order of: appendicular lean soft tissue, LSTLEGS, LSTTRUNK and FMLEGS, FMARMS, FMTRUNK, and LSTARMS. Conclusions These findings indicate the importance of LST hydration, extracellular fluid content, and height for explaining discrepancies between DXA and BIA body composition estimates. These general findings and quantitative interpretation based on the presented data allow for a better understanding of sources of error between two popular segmental body composition techniques and facilitate interpretation of estimates from these technologies.
... The larger proportional bias in Hispanic females is also worth consideration. For example, Tinsley [20] revealed that single-frequency BIA exhibited larger proportional bias in women than men when compared with DXA. These findings are consistent with current study results, which observed larger proportional bias when using MF-BIA in Hispanic females. ...
Article
Body composition algorithms are typically validated using multi-ethnic populations without accounting for ethnicity. This might be problematic when using multi-frequency bioimpedance analysis (MF-BIA) for Hispanics. Group error (i.e., constant error [CE]), individual error (i.e., 95% limits of agreement [LOAs]), and proportional bias of MF-BIA were determined in Hispanic men and women (n = 84 and 97, respectively) when using dual energy X-ray absorptiometry (DXA) as a reference method. Due to the lack of an ethnic-specific impedance equation for Hispanics, it was hypothesized that MF-BIA would be biased when compared to DXA. For body fat percent (BF%), MF-BIA displayed similar CE±95% LOA for the sample (-3.17±5.45%), males (-3.2±5.5%), and females (-3.2±5.4%) compared to DXA. However, moderate proportional bias was present for females (r=0.48). The sample (r=0.22) and males (r=-0.04) had trivial-to-no proportional bias. Regarding fat mass (FM), MF-BIA exhibited CE±95% LOA values of -1.4±4.2 kg for the sample, -1.9±4.6 kg for males, and -0.9±3.6 kg for females. There was strong proportional bias for females (=0.68) and moderate bias for the sample (r=0.36). No proportional bias was observed for males (r=-0.02). For fat-free mass (FFM), males demonstrated the largest CE±95% LOA (1.6±4.6), compared to the sample (1.2±3.9 kg) and females (0.9±3.4 kg) when MF-BIA was compared to DXA. No proportional biases existed for the sample (r=-0.01) or males (r=-0.10). However, females exhibited a moderate, negative bias (r=-0.38). Due to the observed moderate-to-strong proportional biases within body composition estimates, the need for ethnic-specific algorithms is warranted, particularly for the Hispanic female population.
... Tinsley and cols. (25) observed that bias magnitude was greater in women and on subjects with smaller amount of fat mass, indicating that the BIA underestimates fat mass in relation to DXA; on the other hand, in individuals with higher fat mass, the concordance was better. Recent studies showed that in both male and female with BMI < 16, BIA overestimated fat mass by 2.57 kg and for BMI > 18.5 and BMI < 40, BIA underestimated fat mass from 2.51 to 5.67 kg compared with DXA method (12). ...
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Objective To assess the utility of bioimpedance (BIA) and skinfolds thickness (SF) in body fat percentage measuring (%BF) compared to the reference method dual-energy x-ray absorptiometry (DXA) in Brazilian reproductive age women, as well as to estimate of inter- and intra-observer precision for SF. Subjects and methods 170 women aged 18-37 years with BMI between 18 and 39.9 kg/m² were selected for this cross-sectional study. Body density was evaluated through equations proposed by Jackson, Pollock and Ward (1980) (EqJPW) and Petroski (1995) (EqPET), and %BF was estimated by BIA, DXA and Siri’s formula (1961). The SF were measured by two separate observers: A and B (to determine inter-observer variability), who measured the folds at three times with 10-minute interval between them (to determine intra-observer variability – we used only observer A). Results The %BF by DXA was higher than those measured by SF and BIA (p<0.01, for all) of 90 volunteers. The Lin coefficient of agreement was considered satisfactory for %BF values obtained by EqJPW and BIA (0.55) and moderate (0.76) for sum of SF (ΣSF) values obtained by EqJPW and EqPET. No agreement was observed for the values obtained by SF (EqJPW and EqPET), BIA and DXA. Analysis of inter- and intra-observer of 59 volunteers showed that different measures of SF thickness met acceptability standards, as well as the % BF. Conclusion BIA and SF measurements may underestimate %BF compared with DXA. In addition, BIA and SF measurements are not interchangeable with DXA. However, our results suggest the equation proposed by Jackson, Pollock and Ward (three skinfolds) compared to BIA are interchangeable to quantify the %BF in Brazilian women in reproductive age. Furthermore, our results show acceptable accuracy for intra- and inter-observer skinfold measurements. Arch Endocrinol Metab. 2020;64(3):257-68
... Total and regional fat mass, relative body fat and VAT will be quantified via dual-energy X-ray absorptiometry (DXA; GE Lunar Prodigy with enCore software V.16.2). 44 45 Body regions for analysis include the trunk, legs and arms. VAT will be estimated using the built-in functionality of the enCore software. ...
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Introduction Obesity is a major health concern in postmenopausal women, and chronic low-grade inflammation contributes to the development of obesity. Cellular studies and high-fat-diet-induced obese mouse model mimicking obesity show the antiobesity effect of annatto-extracted tocotrienols (TT) with antioxidant capability. We aim to assess the safety and efficacy of TT consumption for lipid-related parameters in obese postmenopausal women. Methods and analysis Eligible obese postmenopausal women will be randomly assigned to placebo group (430 mg olive oil) and TT group (DeltaGold Tocotrienol 70%) for 24 weeks. In the present study, the primary outcome is total/regional fat mass and visceral adipose tissue. The secondary outcomes include lipid profile in serum, mRNA expression of fatty acid synthase and carnitine palmitoyltransferase 1A in fat tissue, oxylipins and endocannabinoids in plasma and adipose tissue, abundance and composition of intestinal microbiome in faeces, high-sensitivity C-reactive protein (hs-CRP) in serum and leptin in serum. Every participant will be evaluated at 0 (prior to starting intervention) and 24 weeks of intervention, except for serum lipid profile and hs-CRP at 0, 12 and 24 weeks. ‘ Intent-to-treat ’ principle is employed for data analysis. Hierarchical linear modelling is used to estimate the effects of dietary TT supplementation while properly accounting for dependency of data and identified covariates. To our knowledge, this is the first randomised, placebo-controlled, double-blinded study to determine dietary TT supplementation on an obese population. If successful, this study will guide the future efficacy TT interventions and TT can be implemented as an alternative for obese population in antiobesity management. Ethics and dissemination This study has been approved by the Bioethics Committee of the Texas Tech University Health Sciences Center, Lubbock. An informed consent form will be signed by a participant before enrolling in the study. The results from this trial will be actively disseminated through academic conference presentation and peer-reviewed journals. Trial registration number NCT03705845 .
... Data were screened for outliers and normal distribution with skewness or kurtosis >2 indicating non-normal distribution (29) . (30,31) . The mean differences in BF % and FFM (i.e. ...
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The purpose of the current study was two-fold: 1) to develop a new dual energy X-ray absorptiometry (DXA)-derived body volume (BV) equation with the GE-Lunar prodigy while utilizing underwater weighing (UWW) as a criterion; and 2) cross-validate the novel DXA-derived BV equation (4C-DXANICKERSON), Wilson DXA-derived BV equation (4C-DXAWILSON), and ADP-derived BV (4C-ADP) in Hispanic adults. Methods: 191 Hispanic adults (18-45yrs) participated in the current study. The development sample consisted of 120 females and males (50% females) whereas the cross-validation sample comprised of 41 females and 30 males (n=71). Criterion body fat percentage (BF%) and fat-free mass (FFM) were determined using a four-compartment (4C) model with UWW as a criterion for BV (4C-UWW). 4C-DXANICKERSON, 4C-DXAWILSON, and 4C-ADP were compared against 4C-UWW in the cross-validation sample. Results: 4C-DXANICKERSON, 4C-DXAWILSON, and 4C-ADP all produced similar validity statistics when compared to 4C-UWW in Hispanic males (all p>0.05). 4C-DXANICKERSON also yielded similar BF% and FFM values as 4C-UWW when evaluating the mean differences (CE) in Hispanic females (CE=-0.79% and 0.38kg; p=0.060 and 0.174, respectively). However, 4C-DXAWILSON produced significantly different BF% and FFM values (CE=3.22% and -2.20kg, respectively; both p<0.001). Additionally, 4C-DXAWILSON yielded significant proportional bias when estimating BF% (p<0.001) whereas 4C-ADP produced significant proportional bias for BF% and FFM (both p<0.05) when evaluated in Hispanic females. Conclusions: Current study findings demonstrate that 4C-DXANICKERSON is a valid measure of BV in Hispanics and is recommended for use in clinics where DXA is the main body composition assessment technique.
... The individual predictive accuracy was evaluated using the 95% limits of agreement (LOA), which were established using the methods of Bland and Altman [30]. Linear regression analysis was performed to test for proportional bias between methods [31]. Additionally, equivalence testing was performed [32]. ...
Article
The validity of dual-energy x-ray absorptiometry (DXA) and multifrequency bioelectrical impedance analysis (MFBIA) for detecting changes in fat mass (FM), fat-free mass (FFM), and body fat percentage (BF%) was evaluated, as compared to a rapid 4-component (4C) model, in 31 females completing 8 weeks of resistance training. Analyses were performed in all participants (ALL) and in subgroups that gained FFM but lost FM (R subgroup) or gained both FFM and FM (G subgroup). It was hypothesized that methods would comparably detect changes in ALL, but discrepancies would occur in subgroup analysis. Changes in body composition did not significantly differ between 4C, DXA, and MFBIA. Equivalence testing indicated that similar changes were detected by DXA and MFBIA, compared to 4C, for ΔFFM in all analyses and ΔBF% in ALL and R subgroup. ΔFM was equivalent to 4C only in R subgroup for DXA and G subgroup for MFBIA. For ΔFM and ΔBF%, DXA and MFBIA produced similar magnitude errors in ALL. However, DXA exhibited lower error in R subgroup, whereas MFBIA exhibited lower error in G subgroup. For ΔFFM, DXA and MFBIA exhibited relatively similar errors in ALL and R subgroup, although MFBIA displayed proportional bias and weaker correlations with 4C than DXA. In G subgroup, MFBIA exhibited lower errors and a higher correlation with 4C ΔFFM than DXA. Although both DXA and MFBIA may have utility for estimating body composition changes during FFM accretion, DXA may be superior during simultaneous FM loss, whereas MFBIA may produce lower error during simultaneous FM gain.
... Research in other populations, such as athletes, has demonstrated varied agreement between DXA and BIA, which could vary based on body size and player position [16,17,19]. In the present study, we did not observe proportional bias at the wholebody level within the entire sample, unlike several prior studies [12,14,30]. However, proportional bias for FM LEGS and FM ARMS were observed, with opposite directions of bias for each segment. ...
Article
Background & aims: Segmental estimates add specificity to body composition evaluation and could potentially have greater health and function implications than whole-body estimates alone. The aim of this study was to quantify the level of agreement between total and segmental fat mass (FM) and lean soft tissue (LST) estimates from dual-energy x-ray absorptiometry (DXA) and single-frequency bioelectrical impedance analysis (SFBIA). Methods: Assessments via DXA (GE® Lunar Prodigy) and SFBIA (RJL Systems® Quantum V) were performed in 179 adults (103 F, 76 M; 30% racial/ethnic minorities). Total and segmental FM and LST estimates were compared in the entire sample, females, and males using null hypothesis significance testing (NHST; via paired-samples t-tests), equivalence testing with 5% equivalence regions, Bland-Altman analysis with linear regression, and additional error metrics. Results: In females and the entire sample, all LST variables except LSTARMS exhibited equivalence between methods, despite statistically significant differences via NHST for most variables. In males, only estimates of LSTTOTAL and appendicular lean soft tissue (ALST) were equivalent between methods. LST variables exhibited minimal proportional bias. All FM variables failed to exhibit equivalence, and most FM variables were underestimated by SFBIA. The magnitude of relative errors for FM generally appeared larger in males than females. Proportional bias was observed for FMLEGS and FMARMS, as well as FMTOTAL in females only. ALST estimates were equivalent between DXA and SFBIA in all analyses, did not differ between methods based on NHST, exhibited relatively low errors, and displayed no proportional bias. Conclusions: In the context of the present study, DXA and SFBIA LST estimates appear to exhibit better overall agreement than FM estimates. Additionally, overall agreement between SFBIA and DXA may be superior in females as compared to males. The relatively strong agreement between ALST estimates indicates potential utility of SFBIA for clinical applications, such as evaluation of sarcopenia. Further investigation into the explanatory physiological (e.g. hydration) and anthropometric (e.g. segment lengths, circumferences, and volumes) variables predicting individual discrepancies between DXA and BIA is warranted.
... Simultaneous determination of lung volume was completed with the oxygen dilution technique via a nitrogen analyzer (Vacu-Med Statistical analyses. The validity of 3C-Field, 3C-DXA SR , 3C-DXA W and DXA were based on the evaluation of predicted values versus 4C-Criterion by calculating the constant error (CE), r value, standard error of estimate (SEE), total error (TE), and proportional bias (28,29). The mean differences in FFM, FM, and BF% (i.e., CE) among the modified 3C models and DXA were compared with the 4C-Criterion (e.g., 3C-Field-4C-Criterion) and analyzed using dependent t-tests (SPSS version 24) with the Bonferroni-adjusted alpha level (P e 0.0125). ...
Article
Modified laboratory- and field-based multicompartment models have been found valid for estimating body composition. However, the comparability between these models is unknown. Purpose: This study determined the validity of field and laboratory three-compartment (3C) models in healthy adults. Methods: One hundred twenty participants (63 men and 57 women; age, 22 ± 5 yr; BMI, 24.9 ± 3.9 kg·m) participated in this study. A criterion four-compartment model (4C-Criterion) was determined with underwater weighing for body volume (BV), bioimpedance spectroscopy for total body water (TBW), and dual-energy X-ray absorptiometry (DXA) for bone mineral content. Modified laboratory-based 3C models were determined using bioimpedance spectroscopy for TBW and two separate DXA BV equations (3C-DXASR and 3C-DXAW) whereas a field-based 3C model (3C-Field) was obtained using single-frequency bioimpedance analysis for TBW and skinfold-derived BV. In addition, a stand-alone DXA assessment was evaluated. Results: The effect size of the mean differences when compared to the 4C-Criterion were trivial to small for all modified 3C models and DXA when estimating fat mass, fat-free mass, and body fat percentage. The standard error of estimate and 95% limits of agreement for all modified 3C models and DXA were similar and considered acceptable. However, 3C-Field produced the lowest total error values and 3C-DXASR produced slightly lower total error values than 3C-DXAW and DXA. Conclusions: The present study found that all modified 3C models and DXA exhibited acceptable errors. When performed by expert personnel, a field-based 3C model appears to be a viable alternative to laboratory-derived models in healthy adults.
... The method of Bland-Altman [18] was used to identify the 95% limits of agreement of the BF% for the prediction models (4C-DXA1 and 4C-DXA2) and 4C-ADP. Linear regression was utilized to evaluate proportional bias between 4C-ADP and the prediction models using the procedures described by Tinsley [19]. ...
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The purpose of this investigation was to determine the validity of 4-compartment (4C) model body fat percent (BF%) estimates when using dual energy x-ray absorptiometry (DXA) derived body volume (BV) equations (4C-DXA1 and 4C-DXA2) in adults with varying body mass index (BMI) and waist circumference (WC) classifications. Each model was compared to a criterion 4C model with air-displacement plethysmography (ADP) generated BV (4C-ADP). Participants were categorized as normal weight (n = 40; NW = BMI<25.0kg/m²); overweight (n = 40; OWBMI = BMI≥25.0 kg/m²); and overweight with at-risk WC (n = 35; OWBMI+WC = BMI≥25.0 kg/m² and WC≥88.0cm for women and 102.0cm for men). 4C-DXA1 produced lower BF% than that derived using the 4C-ADP in NW (CE = -3.0%; p<0.001) while 4C-DXA2 was significantly higher (CE = 4.8%; p<0.001). The SEE and 95% limits of agreement (LOA) were lower for 4C-DXA2 (1.24% and ±2.5%, respectively) than 4C-DXA1 (2.59% and ±5.0%, respectively) and proportional bias was present for both (p<0.05). 4C-DXA1 BF% was not significant in OWBMI (CE = -0.5%; p = 0.112) whereas 4C-DXA2 was higher (CE = 4.5%; p<0.001). The SEE and 95% LOA were lower for 4C-DXA2 (1.20% and ±2.9%, respectively) than 4C-DXA1 (1.92% and ±3.9%, respectively) in OWBMI. Proportional bias was present for 4C-DXA1 (p = 0.007), but not 4C-DXA2 (p = 0.832). 4C-DXA1 and 4C-DXA2 produced significantly higher BF% in OWBMI+WC (CE = 2.2 and 2.3%, respectively; both p<0.001). The SEE and 95% LOA remained lower for 4C-DXA2 (1.15% and ±2.5%, respectively) than 4C-DXA1 (1.84% and ±3.8%, respectively). There was proportional bias for 4C-DXA2 (p = 0.020), but not 4C-DXA1 (p = 0.183) in OWBMI+WC. Only one prediction model (i.e., 4C-DXA1 in OWBMI+WC) revealed valid estimates of BF%. Practitioners are encouraged to use criteria for both BMI and WC when utilizing DXA-derived BV in 4C-models for normal and overweight populations.
... Ling et al (15) reported similar proportional bias for InBody 720 and DXA in women (i.e., underestimation at lower FM and overestimation at higher FM). Proportional bias for BIA and DXA has also been found in adults after consuming high-and low-carbohydrate diets (22). For example, Tinsley (22) revealed Table 5 Comparison Other explanations for the systematic and proportional bias observed in the current investigation should also be discussed. ...
Article
Background: Bioelectrical impedance analysis has evolved over the years to include the use of multiple frequencies and impedance measurements to improve the accuracy and reliability of body composition estimates. The purpose of this investigation was to evaluate the reliability of the InBody230, InBody720, and InBody770 to measure body fat percent (BF%), fat mass (FM), and fat-free mass (FFM) in the general population and to compare results to dual-energy X-ray absorptiometry (DXA). Methods: A total of 31 males and 36 females participated in 2 d of testing separated by 24-72 h. Each visit consisted of a DXA scan, and analysis with the InBody230, InBody720, and InBody770. Results: All 3 bioelectrical impedance devices (InBody230, InBody720, and InBody770) were reliable in men and women as indicated by high intraclass correlation coefficients for BF% (≥0.98), FM (≥0.98), and FFM (≥0.99) and low standard error of measurement for BF% (0.77%-0.99%), FM (0.54-0.87 kg), and FFM (0.58-0.84 kg) and minimum difference for BF% (2.12%-2.73%), FM (1.49-2.39 kg), and FFM (1.60-2.32 kg), respectively. When examining the agreement between the 3 InBody analyzers with DXA, systematic bias (underestimation of BF% and FM and overestimation of FFM) was present for all comparisons (p < 0.05) while proportional bias was present for FM in women and FFM in men. However, there was small individual error for all comparisons as indicated by the standard error of estimate and 95% limits of agreement. Conclusion: The InBody analyzers produce small individual error, which suggest these methods can be used as a surrogate when DXA is not available; however, practitioners should be aware of the systematic bias for all comparisons and proportional bias for FM in women and FFM in men. Furthermore, findings revealed that the research grade models, InBody720 and InBody770, added minimal benefit over the portable InBody230 when assessing BF%, FM, and FFM.
... The 95% LOA indicate the individual predictive accuracy of a method based on a 95% confidence interval. Linear regression was utilized to evaluate proportional bias between the reference method and alternative methods (i.e., varying discrepancies between reference and alternative methods based on RMR values) as previously described (Tinsley 2017). Additionally, stepwise linear regression was utilized to develop RMR prediction equations from relevant variables (i.e., BW, FFM, age, sex, and height). ...
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Estimation of resting metabolic rate (RMR) is an important step for prescribing an individual’s energy intake. The purpose of this study was to evaluate the validity of portable indirect calorimeters and RMR prediction equations in muscular physique athletes. Twenty-seven males (n = 17; body mass index (BMI): 28.8 ± 2.0 kg/m²; body fat: 12.5% ± 2.7%) and females (n = 10; BMI: 22.8 ± 1.6 kg/m²; body fat: 19.2% ± 3.4%) were evaluated. The reference RMR value was obtained from the ParvoMedics TrueOne 2400 indirect calorimeter, and the Cosmed Fitmate and Breezing Metabolism Tracker provided additional RMR estimates. Existing RMR prediction equations based on body weight (BW) or dual-energy X-ray absorptiometry fat-free mass (FFM) were also evaluated. Errors in RMR estimates were assessed using validity statistics, including t tests with Bonferroni correction, linear regression, and calculation of the standard error of the estimate, total error, and 95% limits of agreement. Additionally, new prediction equations based on BW (RMR (kcal/day) = 24.8 × BW (kg) + 10) and FFM (RMR (kcal/day) = 25.9 × FFM (kg) + 284) were developed using stepwise linear regression and evaluated using leave-one-out cross-validation. Nearly all existing BW- and FFM-based prediction equations, as well as the Breezing Tracker, did not exhibit acceptable validity and typically underestimated RMR. The ten Haaf and Weijs (PLoS ONE, 9: e1084602014 (2014)) and Cunningham (1980) (Am. J. Clin. Nutr. 33: 2372–2374 (1980)) FFM-based equations may produce acceptable RMR estimates, although the Cosmed Fitmate and newly developed BW- and FFM-based equations may be most suitable for RMR estimation in male and female physique athletes. Future research should provide additional external cross-validation of the newly developed equations to refine the ability to predict RMR in physique athletes.
... The individual accuracy of models was evaluated using the 95% LOA, which were calculated using the methods of Bland and Altman (3). Linear regression analysis was performed to test for proportional bias (30). A statistically significant (p # 0.05) model coefficient indicated the presence of proportional bias between models, and the size of regression coefficients was evaluated based on the associated magnitude of impact on body composition estimates. ...
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Graybeal, AJ, Moore, ML, Cruz, MR, and Tinsley, GM. Body composition assessment in male and female bodybuilders: a 4-compartment model comparison of dual-energy x-ray absorptiometry and impedance-based devices. J Strength Cond Res XX(X): 000-000, 2018-The purpose of this study was to examine the group and individual accuracy of body composition estimates obtained from multicompartment models, dual-energy x-ray absorptiometry (DXA), and several impedance-based devices in male and female bodybuilders. Twenty-seven male (n = 17; 4-compartment [4C] model fat-free mass index [FFMI]: 25.1 ± 1.8 kg·m; 4C body fat: 11.8 ± 4.4%) and female (n = 10; 4C FFMI: 18.3 ± 1.4 kg·m; 4C body fat: 19.7 ± 4.9%) bodybuilders underwent duplicate assessments using DXA, bioimpedance spectroscopy (BIS), electrical impedance myography (EIM), and 3 bioelectrical impedance analysis (BIA) devices. In addition to utilizing standard output, multicompartment models were generated. For each method, body fat %, FFM, and fat mass were compared with the reference 4C model for the evaluation of group and individual errors. The 3-compartment model with a BIS body water estimate produced the lowest standard error of the estimate, total error (TE), and 95% limits of agreement (LOA) for all variables, although some alternative methods had lower constant error (CE). In general, multicompartment models with BIS or multifrequency BIA body water estimates produced more accurate body composition estimates than single assessment techniques (i.e., DXA, BIS, EIM, and BIA). Single assessment techniques produced low CE and TE for some body composition variables. However, proportional bias was observed for DXA and BIS. All single assessment techniques produced LOA large enough to make the utility of these methods questionable in individual athletes. Appropriate caution should be used when interpreting and utilizing body composition estimates in muscular physique athletes, particularly at the individual level.
... prior to body composition testing has limited implications on testing results [13]. Similarly, Tinsley [24] recently observed that acute food intake of high-and low-carbohydrate content does not largely affect fixed and proportional bias of BIA and DXA. Lastly, previous research has used similar fasting and hydration protocols as that of the current study [25,26]. ...
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Background Most young adults and adolescents in the United Arab Emirates (UAE) do not meet the established internationally recommended physical activity levels per day. The Arab Teen Lifestyle Study (ATLS) physical activity questionnaire has been recommended for measuring self-reported physical activity of Arab adolescents and young adults (aged 14 years to mid-twenties). The first version of the ATLS has been validated with accelerometers and pedometers (r ≤ 0.30). The revised version of the questionnaire (ATLS-2, 2021) needs further validation. The aim of this study was to validate the self-reported subjective sedentary and physical activity time of the ATLS-2 (revised version) physical activity questionnaire with that of Fibion accelerometer-measured data. Methods In this cross-sectional study, 131 healthy adolescents and young adults (aged 20.47 ± 2.16 [mean ± SD] years (range 14–25 years), body mass index 23.09 ± 4.45 (kg/m²) completed the ATLS-2 and wore the Fibion accelerometer for a maximum of 7 days. Participants (n = 131; 81% non-UAE Arabs (n = 106), 13% Asians (n = 17) and 6% Emiratis (n = 8)) with valid ATLS-2 data without missing scores and Fibion data of minimum 10 h/day for at least 3 weekdays and 1 weekend day were analyzed. Concurrent validity between the two methods was assessed by the Spearman rho correlation and Bland-Altman plots. Results The questionnaire underestimated sedentary and physical activity time compared to the accelerometer data. Only negligible to weak correlations (r ≤ 0.12; p > 0.05) were found for sitting, walking, cycling, moderate intensity activity, high intensity activity and total activity time. In addition, a proportional/systematic bias was evident in the plots for all but two (walking and moderate intensity activity time) of the outcome measures of interest. Conclusions Overall, self-reported ATLS-2 sedentary and physical activity time had low correlation and agreement with objective Fibion accelerometer measurements in adolescents and young adults in the UAE. Therefore, sedentary and physical activity assessment for these groups should not be limited to self-reported measures.
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[Purpose] This study aimed to evaluate the differences between predicted resting energy expenditure (REE), using fat-free mass (FFM)-based prediction equations, and measured REE in Korean male collegiate soccer players. [Methods] Fifteen male collegiate soccer players (18-21 years) participated in this study. The REE measurements were conducted using the Douglas bag method. Body composition was measured by dual-energy X-ray absorptiometry (DXA). The differences between the measured REE and predicted REE, using the five FFM-based REE equations were analyzed using the t-test, calculation of errors, regression analysis, and the Bland-Altman method. [Results] The Cunningham (1980) and ten Haaf and Weijs (2014) equations showed significantly overestimated REE (1,808 ± 99 kcal/d, p <0.01; 1,838 ± 103 kcal/d, p <0.01; respectively), but the Owen (1988), Taguchi (2011), and Kim (2015) equations’ estimations were not significantly different from the measured REE (1,589 ± 106 kcal/d, 1,640 ± 124 kcal/d, and 1,622 ± 68 kcal/d, respectively). The Taguchi equation gave the best prediction of REE with the lowest constant error (-6 ± 125) and effect size (-0.05), and a non-significant proportional bias (p = 0.95). [Conclusion] The Taguchi equation is recommended for predicting REE in Korean collegiate soccer players. The selection process of a REE-prediction equation must take into consideration the target population’s characteristics. Future studies are recommended to evaluate the validity of the different FFM-based REE-prediction equations in various Korean athletes.
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Obesity is a health problem known to increase the morbidity and mortality of individuals. Although widely used, body mass index is not considered a good parameter to assess harmful levels of body fat, since is not a good predictor of mortality. Several new methods have been proposed over the years, such as the waist-to-hip radio. Nevertheless, the predictive ability of this method is still inconclusive. This study presents two new evaluation methods (bioelectrical impedance and dual energy x-ray) and assesses the accuracy of both. We evaluated 30 obese patients. The measurements were taken in the morning after a minimum period of 4 h of fasting, with an interval of 10 min between assessments. There was an improvement in the evaluative capacity of BIA in relation to DXA, when compared to previous studies. This led to an equivalence in the evaluative capacity of both formats for assessing body composition.
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Background and aims Smartphone applications (e.g., Google Fit) may be a good alternative tool for accelerometers in estimating energy expenditure of physical activities because they are affordable, easy to use, and freely downloadable on smartphones. We aimed to determine the concurrent validity of the Fibion and Google Fit for measuring energy expenditure of functional tasks in healthy individuals. Methods In this cross-sectional study, 28 healthy individuals (21.25 ± 1.84 years) performed certain tasks (lying, standing, 6-min walk test, treadmill walking, stair climbing and cycling) for ∼90 min, while wearing a Fibion accelerometer on their thigh and having the Google Fit application in a smartphone placed in their trouser pocket. Concurrent validity between the energy expenditure data of the Google Fit and Fibion was assessed using the Spearman rho correlation coefficient (data were not normally distributed), Bland-Altman plots and linear regression. Results Neither energy expenditure for the whole duration nor for the tasks, except sitting + treadmill walking (r = 0.419, p = 0.027), showed significant correlations between the Google Fit and Fibion measurements. A proportional bias was evident for almost all comparisons. Conclusions The Google Fit did not provide valid energy expenditure measurements compared to the Fibion for most of the investigated tasks in healthy individuals.
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BACKGROUND: During weight gain, most of the excess adipose tissue accumulates in the trunk. This alters the body shape and makes collection of anthropometric measurements, especially waist circumference (WC), difficult. OBJECTIVE: To evaluate the sensitivity and applicability of additional abdominal measurements in order to assess body composition of obese women. METHODS: A total of 30 women between 20 and 50 years of age and BMI above 30 kg/m² were assessed. Three WC measurements, were performed: at the umbilical scar designated as WC1 and at 8 and 16 cm above the umbilical scar, designated as WC2, and WC3 respectively. The correlation (r) between these anthropometric measurements and their sum was assessed against the parameters fat mass (FM), free fat mass (FFM), body fat percentage (%BF), and trunk fat percentage (%TF), obtained by total and trunk segmental bioelectric impedance analysis (BIA) as well as by the golden standard total and trunk dual energy X-ray absorptiometry (DXA). RESULTS: The measurements WC1, WC2, WC3, and their sum correlated strongly and moderately with the parameters FM, FFM, and %BF in total BIA and in both total DXA and trunk DXA. CONCLUSION: The results demonstrated a robust correlation between the sum of the three WC measurements and total and trunk DXA in obese women suggesting that such measurements may be a good indicator of body and trunk fat in women, actually superior to BIA results. The use of these three measurements may be an alternative for the assessment of body and trunk fat, in those cases in which the body shape due to adipose tissue trunk accumulation makes accurate classical measurement (WC1) difficult.
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The purpose of this study was to compare body fat estimates and fat-free mass (FFM) characteristics produced by multi-compartment models when utilizing either dual energy X-ray absorptiometry (DXA) or single-frequency bioelectrical impedance analysis (SF-BIA) for bone mineral content (BMC) in a sample of physically active adults. Body fat percentage (BF%) was estimated with five-compartment (5C), four-compartment (4C), three-compartment (3C), two-compartment (2C) models and DXA. The 5C-Wang with DXA for BMC (i.e., 5C-WangDXA) was the criterion. 5C-Wang using SF-BIA for BMC (i.e., 5C-WangBIA), 4C-WangDXA (DXA for BMC), 4C-WangBIA (BIA for BMC), and 3C-Siri all produced similar values as the 5C-WangDXA (r > 0.99; total error (TE) < 0.83%; standard error of estimate < 0.67%; 95% limits of agreement (LOAs) < ±1.35%). The 2C models (2C-Pace, 2C-Siri, and 2C-Brozek) and DXA each prodcued similar SEEs and 95% LOAs (2.13-3.12% and ±4.15-6.14%, respectively). Furthermore, 3C-LohmanDXA (UWW for body volume [BV] and DXA for BMC) and 3C-LohmanBIA (UWW for BV and SF-BIA for BMC) produced the largest 95% LOAs (±5.94-8.63%). The FFM characteristics (i.e., FFM density, water/FFM, mineral/FFM, and protein/FFM) for 5C-WangDXA and 5C-WangBIA were each compared to the “reference body” cadavers of Brozek et al. 5C-WangBIA FFM density differed significantly from the “reference body” in women (1.103 ± 0.007 g/cm3; p<0.001), but no differences were observed for 5C-WangDXA or either 5C model in men. Moreover, water/FFM, and mineral/FFM were significantly lower in men and women when comparing 5C-WangDXA and 5C-WangBIA to the “reference body,” whereas protein/FFM was significantly higher (all p ≤ 0.001). 3C-LohmanBIA and 3C-LohmanDXA produced similar error as 2C models and DXA and are therefore not recommended multi-compartment models. Although more advanced multi-compartment models (e.g., 4C-Wang and 5C-Wang) can utilize BIA-derived BMC with minimal impact on body fat estimates, the increased accuracy of these models over 3C-Siri is minimal.
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Background: Bioelectrical Impedance Analysis (BIA) is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM) estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17-24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA) as a reference method. Student's t-test (for paired sample), linear regression analysis, and Bland-Altman method were used to test the validity of the BIA equations. Results: Predictive BIA equations showed significant differences in FFM compared to DXA (p < 0.05) and large limits of agreement by Bland-Altman. Predictive BIA equations explained 68% to 88% of FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Conclusion: Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.
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Background: Sarcopenia is a common geriatric syndrome associated with serious adverse health outcomes. The European Working Group on Sarcopenia in Older People (EWGSOP) suggests different methods for case finding for sarcopenia. However, data comparing the different methodological options are scarce for geriatric inpatients. Methods: On the basis of the recommendations of the EWGSOP sixty geriatric inpatients underwent measurement of gait speed, hand grip strength and muscle mass by both, dual X-ray absorptiometry (DXA) and bioimpedance analysis (BIA). By linear regression analysis and Bland-Altman plots muscle mass measurements of DXA and BIA were compared. Outcomes of the DXA- and BIA-based approaches for classifying participants as having normal or reduced muscle mass and sarcopenia according to the EWGSOP case finding algorithm were compared by raw agreement and kappa statistics. Finally, on the hypothetical assumption that the DXA-based approach can be set as reference, the performance of the BIA-based approach is illustrated. Results: Muscle mass measured by BIA was highly correlated to DXA (r > 0.9), but BIA systematically overestimated muscle mass. The mean difference between DXA and BIA was -1.30 kg (p < 0.001) for appendicular and -2.33 kg (p < 0.001) for total muscle mass. The raw agreement between the DXA- and BIA-based approaches for classifying participants as having normal or reduced muscle mass was at best 80 % depending on the BIA cut-offs used. Functional prescreening according to the sarcopenia case finding algorithm of the EWGSOP reduced the need for muscle mass measurement by 37 %, but only marginally changed the agreement between the DXA- and BIA-based approaches. Conclusion: Clinicians should be aware that in geriatric inpatients the BIA-based approaches resulted in highly different subgroups of sarcopenic/non-sarcopenic subjects compared to the DXA-based approach following the EWGSOP case finding algorithm. In this pilot-study the BIA-based approach misclassified nearly 1 out of 6 patients if the DXA-based approach is taken as reference.
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We aimed to assess the agreement of a commercially available bioelectrical impedance analysis (BIA) device in measuring changes in fat, lean and bone mass over a 10-week lifestyle intervention, with dual energy X-ray absorptiometry (DXA) as reference. A sample of 136 volunteers (18-66 years) underwent a physical activity intervention to enhance lean mass and reduce fat mass. BIA (Tanita BC545) and DXA (Hologic Explorer) measures of whole-body composition were taken at baseline and at the end of the intervention. After an average of 74 ± 18 days intervention, DXA showed significant changes in 2 of 3 outcome variables: reduced fat mass of 0.802 ± 1.092 kg (P < 0.001), increased lean mass of 0.477 ± 0.966 kg (P < 0.001); minor non-significant increase of 0.007 ± 0.041 kg of bone mass (P = 0.052). The respective changes in BIA measures were a significant reduction of 0.486 ± 1.539 kg fat (P < 0.001), but non-significant increases of 0.084 ± 1.201 kg lean mass (P = 0.425), and 0.014 ± 0.091 kg bone (P = 0.074). Significant, but moderately weak, correlations were seen in absolute mass changes between DXA and BIA: 0.511 (fat), 0.362 (lean) and 0.172 (bone). Compared to DXA, BIA demonstrated mediocre agreement to changes in fat mass, but poor agreement to lean mass changes. BIA significantly underestimated the magnitude of changes in fat and lean mass compared to DXA.
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The aim of this study is to investigate the effect of a 3-day high-carbohydrate diet (≥75% of total calories) on body composition using dual-energy X-ray absorptiometry (DXA). Twenty non-obese young men (age 22.7 ± 2.6 years, BMI 23.5 ± 2.1 kg/m(2)) completed the study. Two DXA tests were performed for the measurement of total body weight, body mass index (BMI), body fat percentage as well as total, appendicular and central lean body mass (LBM) before and after a high-carbohydrate diet for 3 days. In addition, the participants completed a food diary during the 3-day high-carbohydrate diet to determine the mean percentage of carbohydrates consumed from total kilocalories. The mean percentage of carbohydrate intake over 3 days was 83.7 ± 8.4%. Our results showed a significant increase in total body weight, BMI as well as total and appendicular LBM after the high-carbohydrate diet (p < 0.01). In addition, we observed a strong tendency for lower body fat percentage values after the intervention (p = 0.05). No significant difference was observed for central LBM. These results indicate that the effect of an acute high carbohydrate diet seems to affect body composition values using DXA, such as total LBM. This study may lead to the need of standardizing a diet prior to using DXA. © 2015 S. Karger AG, Basel.
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The aim of the present study was to analyse the agreement of bioelectrical impedance analysis (BIA) compared with dual-energy X-ray absorptiometry (DXA) and MRI in estimating body fat, skeletal muscle and visceral fat during a 12-month weight loss intervention. A total of nineteen obese adults (twelve females, seven males) aged 20·2-48·6 years, mean BMI 34·6 (se 0·6) kg/m2, participated in the study. Body fat, skeletal muscle and visceral fat index were measured by BIA (Omron BF-500; Omron Medizintechnik) and compared with DXA (body fat and skeletal muscle) at baseline, 5 and 12 months, and with MRI (visceral fat) at baseline and 5 months. The subjects lost 8·9 (se 1·8) kg (9·0 (se 1·7) %) of body weight during the 12-month intervention. BIA, as compared to DXA, accurately assessed loss of fat (7·0 (se 1·5) v. 7·0 (se 1·4) kg, P = 0·94) and muscle (1·0 (se 0·2) v. 1·4 (se 0·3) kg, P = 0·18). While body fat was similar by the two methods, skeletal muscle was underestimated by 1-2 kg using BIA at each time point. Compared to MRI, BIA overestimated visceral fat, especially in males. BIA and DXA showed high correlations for kg fat, both cross-sectionally and longitudinally (r 0·91-0·99). BIA, compared with DXA and MRI, detected kg muscle and visceral fat more accurately cross-sectionally (r 0·77-0·87 and r 0·40-0·78, respectively) than their changes longitudinally (r 0·24-0·61 and r 0·46, respectively). BIA is at its best when assessing the amount or changes in fat mass. It is a useful method for measuring skeletal muscle, but limited in its ability to measure visceral fat.
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Dual-energy x-ray absorptiometry (DXA) is becoming a popular tool to measure body composition in athletes, owing to its ease of operation and comprehensive analysis of body composition. This study represents the first systematic investigation of the reliability of DXA measurements of body composition in trained individuals and includes measurements of daily variability as well as the specific effect of the intake of a meal. Physically active young adults (15 females, 16 males) underwent five whole-body DXA scans during a 2-d period: in the morning after an overnight fast, ~5 min later after repositioning on the scanning bed, ~8 h later after usual daily activities, and the next morning before and ~30 min after consumption of a simple breakfast. Magnitudes of typical (standard) errors of measurement and changes in the mean of DXA measures were assessed by standardization. Repositioning produced trivial typical errors for whole-body composition, whereas regional body composition showed substantial errors. Daily activities and consumption of breakfast generally produced a substantial increase in the typical error and mean of DXA estimates of total and regional lean mass and associated body mass. Having a standardized scanning protocol and fasted subjects is the most practical way to minimize measurement errors. Future studies involving DXA in measuring body composition should report their scanning and analysis protocol with their associated typical errors of measurement so that the level of reliability can be assessed.
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To investigate the effect of a breakfast meal on bioelectrical impedance (BI). Three separate interventions. A university based study. Young, healthy volunteers recruited from staff. Twenty-nine subjects (11 men, 18 women), ten subjects (two men and eight women) and 13 subjects (2 men and 11 women) completed the first, second and third protocol, respectively. Total body BI (protocol 1) or both total body BI and segmental BI (namely arm, leg or torso BI); (protocol 3) was measured in the fasting state and for up to 5 h after the consumption of a breakfast meal containing 28% energy from fat. In the second protocol, total body BI was measured in the same way on two occasions after subjects consumed isocaloric meals containing either 28% energy or 4% energy from fat. Consumption of a 2300 kJ meal was followed by a significant (P = 0.0002) decrease in BI (95% confidence intervals 12.5 and 35.3), a change which occurred 2 h after the meal and continued until 5 h, irrespective of meal fat content. The fall in total body BI was accounted for primarily by a fall in the BI of the limbs, with virtually no contribution from the torso. To ensure consistency in the interpretation of BI for body composition analysis, it is important that measurements are made in the fasting state.
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The ability of modified alternate-day fasting (ADF; ie, consuming 25% of energy needs on the fast day and ad libitum food intake on the following day) to facilitate weight loss and lower vascular disease risk in obese individuals remains unknown. This study examined the effects of ADF that is administered under controlled compared with self-implemented conditions on body weight and coronary artery disease (CAD) risk indicators in obese adults. Sixteen obese subjects (12 women, 4 men) completed a 10-wk trial, which consisted of 3 phases: 1) a 2-wk control phase, 2) a 4-wk weight loss/ADF controlled food intake phase, and 3) a 4-wk weight loss/ADF self-selected food intake phase. Dietary adherence remained high throughout the controlled food intake phase (days adherent: 86%) and the self-selected food intake phase (days adherent: 89%). The rate of weight loss remained constant during controlled food intake (0.67 +/- 0.1 kg/wk) and self-selected food intake phases (0.68 +/- 0.1 kg/wk). Body weight decreased (P < 0.001) by 5.6 +/- 1.0 kg (5.8 +/- 1.1%) after 8 wk of diet. Percentage body fat decreased (P < 0.01) from 45 +/- 2% to 42 +/- 2%. Total cholesterol, LDL cholesterol, and triacylglycerol concentrations decreased (P < 0.01) by 21 +/- 4%, 25 +/- 10%, and 32 +/- 6%, respectively, after 8 wk of ADF, whereas HDL cholesterol remained unchanged. Systolic blood pressure decreased (P < 0.05) from 124 +/- 5 to 116 +/- 3 mm Hg. These findings suggest that ADF is a viable diet option to help obese individuals lose weight and decrease CAD risk. This trial was registered at clinicaltrials.gov as UIC-004-2009.
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To evaluate the influence of hydration status on the estimation of body composition using dual-energy X-ray absorptiometry (DXA), six normal volunteers and seven patients on maintenance haemodialysis were investigated using two different DXA machines (Lunar DPX, Hologic QDR 1000/W). Normal volunteers were studied (Hologic QDR 1000/W) before and 1 h after ingestion of breakfast, lunch and dinner (drinking various amounts of liquids at each meal, 0.5-2.4 kg). Whereas bone mineral content and body fat mass did not change, lean body mass of the trunk increased as a consequence of the meals. Conversely in patients on haemodialysis (Lunar DPX), lean body mass decreased in all segments of the body as a consequence of removal of 0.9-4.4 kg of salt-containing fluid by haemodialysis (trunk 61%, legs 30%, arms 5.5% and rest of the body 3.5%), whereas bone mineral content and body fat mass remained unchanged. However, this finding(s) did not hold true in one particular patient with bilateral hip prostheses. Measurement of body composition in eight normal volunteers on the same day with both machines showed similar results for lean and fat mass, whereas bone mineral content was found to be 17% higher using the Lunar DPX. In summary, in centres where both machines are available, follow-up of one individual patient should always be performed using the same equipment. In addition, hydration status and food intake must be taken into account when repetitive measurements of lean body mass are performed in the same patient.
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Supercompensated muscle glycogen can be achieved by using several carbohydrate (CHO)-loading protocols. This study compared the effectiveness of two "modified" CHO-loading protocols. Additionally, we determined the effect of light cycle training on muscle glycogen. Subjects completed a depletion (D, n = 15) or nondepletion (ND, n = 10) CHO-loading protocol. After a 2-day adaptation period in a metabolic ward, the D group performed a 120-min cycle exercise at 65% peak oxygen uptake (VO2 peak) followed by 1-min sprints at 120% VO2 peak to exhaustion. The ND group performed only 20-min cycle exercise at 65% VO2 peak. For the next 6 days, both groups ate the same high-CHO diets and performed 20-min daily cycle exercise at 65% VO2 peak followed by a CHO beverage (105 g of CHO). Muscle glycogen concentrations of the vastus lateralis were measured daily with 13C magnetic resonance spectroscopy. On the morning of day 5, muscle glycogen concentrations had increased 1.45 (D) and 1.24 (ND) times baseline (P < 0.001) but did not differ significantly between groups. However, on day 7, muscle glycogen of the D group was significantly greater (p < 0.01) than that of the ND group (130 +/- 7 vs. 104 +/- 5 mmol/l). Daily cycle exercise decreased muscle glycogen by 10 +/- 2 (D) and 14 +/- 5 mmol/l (ND), but muscle glycogen was equal to or greater than preexercise values 24 h later. In conclusion, a CHO-loading protocol that begins with a glycogen-depleting exercise results in significantly greater muscle glycogen that persists longer than a CHO-loading protocol using only an exercise taper. Daily exercise at 65% VO2 peak for 20 min can be performed throughout the CHO-loading protocol without negatively affecting muscle glycogen supercompensation.
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Background/objectives: We evaluated the agreement of air displacement plethysmography (ADP) and bioelectrical impedance analysis (BIA) with dual-energy X-ray absorptiometry (DXA) for the assessment of percent fat mass (%FM) in morbidly obese women. Subjects/methods: Fifty-seven women aged 19-55 years and with a body mass index (BMI) ranging from 37.3 to 55.2 kg/m(2) were studied. Values of %FM were obtained directly from ADP and DXA, whereas for BIA we estimated fat-free mass (FFM) from an equation for morbidly obese subjects and calculated %FM as (weight-FFM)/weight. Results: The mean (s.d.) difference between ADP and DXA for the assessment of %FM was -2.4% (3.3%) with limits of agreement (LOA) from -8.8% to 4.1%. The mean (s.d.) difference between BIA and DXA for the assessment of %FM was 1.7% (3.3%) with LOA from -4.9% to 8.2%. Conclusion: ADP-DXA and BIA-DXA are not interchangeable methods for the assessment of body composition in morbidly obese women.
Article
Purpose: To examine the effects of acute pre-assessment diets on body composition estimates obtained by dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). Methods: In a counterbalanced design, 48 males and females were provided with two one-day diets: high-carbohydrate diet (9 g CHO/kg) and very low-carbohydrate diet (1 to 1.5 g CHO/kg). For each condition, body composition was assessed in the morning after an overnight fast, in the afternoon after feeding, and the following morning after a second overnight fast. Results: Acute food ingestion, regardless of macronutrient content, altered DXA and BIA body composition estimates, and both sexes responded similarly. DXA total and regional lean soft tissue estimates increased up to 1.7% and 3% on average in response to feeding, with individual increases of over 4.5% and 9%. DXA total and trunk fat mass estimates decreased by up to 3% on average. All DXA-derived measures of body composition returned to baseline values after the second overnight fast. Impedance measured by BIA decreased by 4.4% in response to feeding, leading to a 2% increase in total body water and fat-free mass, with individual increases up to 4.5%. BIA fat mass estimates decreased 1.4 to 2.4%, with individual decreases of up to 10%. Unlike DXA, most BIA-derived estimates did not return to baseline values after a second overnight fast. Conclusion: Acute food and fluid intake can artificially influence body composition estimates, regardless of macronutrient content. An overnight fast is likely sufficient pre-assessment dietary control for DXA and possibly sufficient for BIA.
Article
The aim of this study was to compare total and segmental body composition results between BIA and DXA scan and to test the reproducibility of BIA in obese adolescents. We hypothesized that BIA offers an accurate and reproducible method to assess body composition in adolescents with obesity. Whole-body and segmental body composition were assessed by bio-impedance analysis (BIA-Tanita MC-780) and dual x-ray absorptiometry (DXA, Hologic) among 138 (110 girls and 28 boys) obese adolescents (Tanner stage 3-5) aged 14 ± 1.5 years old. The BIA analysis was replicated on three identical occasions in 32 participants to test the reproducibility of the methods. Whole body fat mass percentage was significantly higher using the BIA method compared with DXA-FM% (40.6 ± 7.8 vs. 38.8 ± 4.9 %, p < 0.001), which represents a 4.8% overestimation of the BIA technic compared with DXA. Similarly, Fat Mass expressed in kg is overestimated by 2.8% using BIA (35.8 ± 11.7 kg) compared with the DXA measure (34.3 ± 8.7 kg) (p < 0.001) and Fat-Free Mass is underestimated by -6.1% using BIA (p < 0.001). Except for the right arm and leg percentage of fat mass, all the segmental measures of body composition are significantly different between the two methods. ICC and Lin coefficients showed great agreement and concordance between both methods in assessing whole-body body composition. ICC between the three BIA measures ranged from 0.99 to 1 for body weight, body fat and FFM. BIA offers an acceptable and reproducible alternative to assess body composition in obese adolescents, with however a loss of correlation between BIA and DXA with increasing body fat; its validity remains uncertain for segmental analysis among obese youth.
Article
AimThe purpose of the present study was to examine the agreement of segmental multifrequency bioelectrical impedance analysis (SMF-BIA) for the assessment of whole-body and appendicular fat mass (FM) and lean soft tissue mass (LSTM) compared with dual-energy X-ray absorptiometry (DXA) in a community-dwelling Japanese older population.Methods The study population included 551 community-dwelling Japanese older adults (241 men and 310 women) aged between 65 and 87 years. Agreement between SMF-BIA and DXA for whole-body and appendicular body composition was assessed using simple linear regression and Bland–Altman analysis.ResultsHigh coefficients of determination (R2) were observed for whole-body FM (R2 = 0.91, standard error of estimate [SEE] = 1.4 kg in men and R2 = 0.94, SEE = 1.2 kg in women) between SMF-BIA and DXA. The R2 coefficient for whole-body LSTM was higher in men (R2 = 0.88, SEE = 1.9 kg) than in women (R2 = 0.83, SEE = 1.5 kg). There was systematic bias with overestimation of whole-body FM and underestimation of whole-body LSTM by SMF-BIA. Proportional bias was noted for measurement of whole-body FM and LSTM in both men and women, but there was no proportional bias between the two methods for measurement of appendicular LSTM (r = 0.05, P = 0.428 and r = −0.10, P = 0.070 for men and women, respectively).ConclusionSMF-BIA is a good alternative for estimating the whole-body and appendicular FM and LSTM in a community-dwelling Japanese older population, although it overestimated FM and underestimated LSTM when validated against DXA. Geriatr Gerontol Int 2014; ●●: ●●–●●.
Article
Background Bioelectric impedance analysis (BIA) is commonly used in research to assess body composition. However, studies that validate the accuracy of BIA exclusively in post-menopausal women are lacking. The main purpose of the present study was to evaluate the agreement of multi-frequency (MF)-BIA and single-frequency (SF)-BIA with dual-energy X-ray absorptiometry (DXA) in the estimation of fat mass (FM) and fat-free mass (FFM) among post-menopausal women with variation in body mass index (BMI) and physical activity (PA).MethodsFM and FFM were estimated by BIA and DXA in 146 post-menopausal women with a mean (SD) age of 62.8 (5.2) years. PA was determined by an accelerometer.ResultsThe mean (SD) difference between MF-BIA and DXA was −1.8 (1.8) kg (P = 0.08) and 1.3 (1.8) kg (P = 0.01) for FM and FFM, respectively. SF-BIA provided a significantly lower estimate of FM [−2.0 (2.2) kg; P = 0.04] and a higher estimate of FFM [1.8 (2.4) kg; P < 0.01] compared to DXA. MF-BIA provided significantly better estimates of FM and FFM with narrower limits of agreement than SF-BIA in obese and insufficiently active subjects. In other BMI and PA groups, both BIA devices showed a similar deviation from DXA.ConclusionsBIA tends to underestimate FM and overestimate FFM relative to DXA. MF-BIA appears to be a more appropriate method for the assessment of body composition than SF-BIA in post-menopausal woman with BMI >30 kg/m2 and in those who are insufficiently active.
Article
Background/objective: We aimed to examine the accuracy of segmental multi-frequency bioelectrical impedance analysis (SMF-BIA) for the assessment of whole-body and appendicular fat mass (FM) and lean soft tissue mass (LM) in frail older women, using dual-energy X-ray absorptiometry (DXA) as a reference method. Subjects/methods: All 129 community-dwelling Japanese frail older women with a mean age of 80.9 years (range, 75-89 years) from the Frailty Intervention Trial were recruited. The agreements between SMF-BIA and DXA for whole-body and appendicular body composition were assessed using simple linear regression and Bland-Altman analysis. Results: High coefficients of determination (R(2)) for whole-body FM (R(2)=0.94, s.e. of estimate (SEE)=1.2 kg), whole-body LM (R(2)=0.85, SEE=1.4 kg), and appendicular FM (R(2)=0.82, SEE=1.1 kg) were observed between SMF-BIA and DXA. The R(2) coefficient for appendicular LM was moderate (R(2)=0.76, SEE=0.8 kg). Bland-Altman plots demonstrated that there was systematic (constant) bias (that is, DXA minus SMF-BIA) with overestimation of whole-body FM (bias=-1.2 kg, 95% confidence interval (CI)=-1.5 to -0.1) and underestimation of whole-body LM (bias=2.1 kg, 95% CI=1.8-2.3) by SMF-BIA. Similar, the appendicular measurements also demonstrated systematic bias with overestimation of appendicular FM (bias=-0.3 kg, 95% CI=-0.5 to -0.1) and underestimation of whole-body LM (bias=1.5 kg, 95% CI=1.4-1.7) by SMF-BIA. In addition, the individual level accuracy demonstrated a non-proportional bias for whole-body LM (r=0.08, P=0.338) and appendicular FM (r=0.07, P=0.413). Conclusions: SMF-BIA had acceptable accuracy for the estimation of whole-body and appendicular FM and LM in frail older women, although SMF-BIA underestimated LM and overestimated FM relative to DXA.
Article
Methods of analysis used in the comparison of two methods of measurement are reviewed. The use of correlation, regression and the difference between means is criticized. A simple parametric approach is proposed based on analysis of variance and simple graphical methods.
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To evaluate measurements of human body composition using dual energy X-ray absorptiometry and to assess its precision and variations within and between observers as well as the influence of food and fluid intake. Experimental study. District hospital, Denmark. 17 volunteers, 12 male and 5 female. Repeated scans under standard conditions. Precision, variations within and between observers, and influence of the degree of hydration. The repeatability coefficients and the coefficients of variation (CV) were obtained for the four body compartments: tissue mass 416 g (CV 0.2%); fat mass 1117 g (CV 2.6%); lean tissue mass 1425 g (CV 0.9%), and total bone mineral content, (BMC) 109 g (CV 1.2%). There was no significant intraobserver variation. There was little interobserver variation in assessing tissue mass and BMC, but there were significant differences when judging fat and lean tissue mass. Drinking resulted in significantly increased values for tissue and lean tissue mass, which corresponded to the intake. DXA is precise and reproducible with little variation within and between observers. It might be useful in clinical studies.
Article
Body composition measurement is a valuable tool for assessing nutritional status and physical fitness in a variety of clinical settings. Although bioimpedance analysis (BIA) can easily assess body composition, its accuracy remains unclear. We examined the accuracy of direct segmental multi-frequency BIA technique (DSM-BIA) in assessing different body composition parameters, using dual energy X-ray absorptiometry (DEXA) as a reference standard. A total of 484 middle-aged participants from the Leiden Longevity Study were recruited. Agreements between DSM-BIA and DEXA for total and segmental body composition quantification were assessed using intraclass correlation coefficients and Bland-Altman plots. Excellent agreements were observed between both techniques in whole body lean mass (ICC female = 0.95, ICC men = 0.96), fat mass (ICC female = 0.97, ICC male = 0.93) and percentage body fat (ICC female = 0.93, ICC male = 0.88) measurements. Similarly, Bland-Altman plots revealed narrow limits of agreements with small biases noted for the whole body lean mass quantification but relatively wider limits for fat mass and percentage body fat quantifications. In segmental lean muscle mass quantification, excellent agreements between methods were demonstrated for the upper limbs (ICC female≥0.91, ICC men≥0.87) and lower limbs (ICC female≥0.83, ICC male≥0.85), with good agreements shown for the trunk measurements (ICC female = 0.73, ICC male = 0.70). DSM-BIA is a valid tool for the assessments of total body and segmental body composition in the general middle-aged population, particularly for the quantification of body lean mass.
Article
In clinical measurement comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analysed inappropriately, notably by using correlation coefficients. The use of correlation is misleading. An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
Article
Bioelectrical impedance analysis (BIA) can be used for estimating body composition. Earlier studies showed that the ingestion of meals lowers bioelectrical impedance, but none studied the effect of repeated ingestion of an identical meal in narrow intervals on impedance measurements during 24 h. The objectives were to study the effect on bioelectrical impedance of 3 identical meals and to compare the results from single-frequency BIA measurements with those from multiple-frequency BIA measurements. Bioelectrical impedance was measured 18 times during 24 h in 18 healthy subjects [10 women and 8 men; x +/- SD age: 31.5 +/- 11.7 y; body mass index (in kg/m(2)): 22.2 +/- 2.7]. An identical meal was given at breakfast, lunch, and dinner. Bioelectrical impedance decreased after ingestion of a standard meal (P < 0.05). The decrease in impedance lasted 2-4 h after each meal. The decrease was additive during the day, although it was more pronounced after the first meal because of the combined effect of rising from the supine position and meal ingestion. This is an important consideration when calculating body composition: percentage of body fat varied by 8.8% from the highest to the lowest measurement in women and by 9.9% from the highest to the lowest measurement in men. The bioelectrical impedance at 50 kHz was identical when measured with multiple frequencies or a single frequency. The ingestion of meals leads to an additive decrease in bioelectrical impedance and thus to a decrease in the calculated percentage of body fat.
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Untested alternative weight loss diets, such as very low carbohydrate diets, have unsubstantiated efficacy and the potential to adversely affect cardiovascular risk factors. Therefore, we designed a randomized, controlled trial to determine the effects of a very low carbohydrate diet on body composition and cardiovascular risk factors. Subjects were randomized to 6 months of either an ad libitum very low carbohydrate diet or a calorie-restricted diet with 30% of the calories as fat. Anthropometric and metabolic measures were assessed at baseline, 3 months, and 6 months. Fifty-three healthy, obese female volunteers (mean body mass index, 33.6 +/- 0.3 kg/m(2)) were randomized; 42 (79%) completed the trial. Women on both diets reduced calorie consumption by comparable amounts at 3 and 6 months. The very low carbohydrate diet group lost more weight (8.5 +/- 1.0 vs. 3.9 +/- 1.0 kg; P < 0.001) and more body fat (4.8 +/- 0.67 vs. 2.0 +/- 0.75 kg; P < 0.01) than the low fat diet group. Mean levels of blood pressure, lipids, fasting glucose, and insulin were within normal ranges in both groups at baseline. Although all of these parameters improved over the course of the study, there were no differences observed between the two diet groups at 3 or 6 months. beta- Hydroxybutyrate increased significantly in the very low carbohydrate group at 3 months (P = 0.001). Based on these data, a very low carbohydrate diet is more effective than a low fat diet for short-term weight loss and, over 6 months, is not associated with deleterious effects on important cardiovascular risk factors in healthy women.
Comparison of dual-energy x-ray absorptiometry, air displacement plethysmography and bioelectrical impedance analysis for the assessment of body composition in morbidly obese women
  • G Bedogni
  • F Agosti
  • De Col
  • A Marazzi
  • N Tagliaferri
  • A Sartorio
Bedogni G, Agosti F, De Col A, Marazzi N, Tagliaferri A, Sartorio A. Comparison of dual-energy x-ray absorptiometry, air displacement plethysmography and bioelectrical impedance analysis for the assessment of body composition in morbidly obese women. Eur J Clin Nutr 2013;67:1129-32. http://dx.doi.org/10.1038/ejcn.2013.159.