Four-component model for the assessment of body composition in humans: comparison with alternative methods, and evaluation of the density and hydration of fat-free mass

1. Body composition was assessed in 28 healthy subjects (body mass index 20–28 kg/m2) by dual-energy X-ray absorptiometry, deuterium dilution, densitometry, 40K counting and four prediction methods (skinfold thickness, bioelectrical impedance, near-i.r. interactance and body mass index). Three- and four-component models of body composition were constructed from combinations of the reference methods. The results of all methods were compared. Precision was evaluated by analysis of propagation of errors. The density and hydration fraction of the fat-free mass were determined. 2. From the precision of the basic measurements, the propagation of errors for the estimation of fat (± sd) by the four-component model was found to be ± 0.54 kg, by the three-component model, ± 0.49 kg, by deuterium dilution, ± 0.62 kg, and by densitometry, ± 0.78 kg. Precision for the measurement of the density and hydration fraction of fat-free mass was ± 0.0020 kg/l and ± 0.0066, respectively. 3. The agreement between reference methods was generally better than between reference and alternative methods. Dual-energy X-ray absoptiometry predicted three- and four-component model body composition slightly less well than densitometry or deuterium dilution (both of which greatly influence these multi-component models). 4. The hydration fraction of fat-free mass was calculated to be 0.7382 ± 0.0213 (range 0.6941–0.7837) and the density of fat-free mass was 1.1015 ± 0.0073 kg/1 (range 1.0795–1.1110 kg/1), with no significant difference between men and women for either. 5. The results suggest that the three- and four-component models are not compromised by errors arising from individual techniques. Dual-energy X-ray absorptiometry would appear to be a suitable alternative method for the assessment of body composition in these healthy adults. The traditional mean value assumed for density of the fat-free mass in classic densitometry (1.1 kg/l) appears to be appropriate, and the mean hydration fraction was close to values which are generally applied to the fat-free mass (0.72–0.73). Despite concealing considerable inter-individual variation, these mean values may be applied to groups with characteristics similar to those in this study. Finally, with the notable exception of skinfold thickness, bedside prediction methods show poor agreement with both the three- and the four-component models.

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QDR 4500A DXA overestimates fat-free mass compared with criterion methods

Journal of Applied Physiology ◽

10.1152/japplphysiol.00732.2002 ◽

2003 ◽

Vol 94 (3) ◽

pp. 959-965 ◽

Cited By ~ 49

Author(s):

Frances Tylavsky ◽

Timothy Lohman ◽

Barbara A. Blunt ◽

Dale A. Schoeller ◽

Thomas Fuerst ◽

...

Keyword(s):

Lower Estimate ◽

Dual Energy ◽

Fat Free Mass ◽

Component Model ◽

Men And Women ◽

Hydration Level ◽

X Ray ◽

Beam System ◽

Four Component Model ◽

Total Body

This study evaluated the accuracy with which the dual-energy X-ray absorptiometer (Hologic QDR 4500A) measured fat-free mass (FFM), fat mass (FM), and hydration of FFM. In a study of 58 men and women (ages 70–79 yr), the QDR 4500A was found to provide a systematically higher estimate of FFM and lower estimate of FM than a four-component model of body composition. A correction factor from this study was developed and applied to two other samples ( n = 13 and 37). We found mean corrected levels of FFM and FM to be equivalent to that obtained by the four-component model or total body water. In addition, the hydration of the corrected FFM was closer to the established hydration level in adult samples and that obtained from the four-component model. These findings suggest that the current calibration of the fan-beam system of the Hologic QDR 4500A provides an overestimate of FFM and underestimate of FM compared with reference methods.

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In vivo validation of whole body composition estimates from dual-energy X-ray absorptiometry

Journal of Applied Physiology ◽

10.1152/jappl.1997.83.2.623 ◽

1997 ◽

Vol 83 (2) ◽

pp. 623-630 ◽

Cited By ~ 173

Author(s):

Barry M. Prior ◽

Kirk J. Cureton ◽

Christopher M. Modlesky ◽

Ellen M. Evans ◽

Mark A. Sloniger ◽

...

Keyword(s):

Body Composition ◽

Dual Energy ◽

Component Model ◽

Whole Body ◽

Body Density ◽

X Ray ◽

Athletic Status ◽

Musculoskeletal Development ◽

Four Component Model ◽

The Difference

Prior, Barry M., Kirk J. Cureton, Christopher M. Modlesky, Ellen M. Evans, Mark A. Sloniger, Michael Saunders, and Richard D. Lewis. In vivo validation of whole body composition estimates from dual-energy X-ray absorptiometry. J. Appl. Physiol. 83(2): 623–630, 1997.—We validated whole body composition estimates from dual-energy X-ray absorptiometry (DEXA) against estimates from a four-component model to determine whether accuracy is affected by gender, race, athletic status, or musculoskeletal development in young adults. Measurements of body density by hydrostatic weighing, body water by deuterium dilution, and bone mineral by whole body DEXA were obtained in 172 young men ( n = 91) and women ( n = 81). Estimates of body fat (%Fat) from DEXA (%FatDEXA) were highly correlated with estimates of body fat from the four-component model [body density, total body water, and total body mineral (%Fatd,w,m); r = 0.94, standard error of the estimante (SEE) = 2.8% body mass (BM)] with no significant difference between methods [mean of the difference ± SD of the difference = −0.4 ± 2.9 (SD) % BM, P = 0.10] in women and men. On the basis of the comparison with %Fatd,w,m, estimates of %FatDEXA were slightly more accurate than those from body density ( r = 0.91, SEE = 3.4%; mean of the difference ± SD of the difference = −1.2 ± 3.4% BM). Differences between %FatDEXA and %Fatd,w,m were weakly related to body thickness, as reflected by BMI ( r= −0.34), and to the percentage of water in the fat-free mass ( r = −0.51), but were not affected by race, athletic status, or musculoskeletal development. We conclude that body composition estimates from DEXA are accurate compared with those from a four-component model in young adults who vary in gender, race, athletic status, body size, musculoskeletal development, and body fatness.

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Density of the fat-free mass and estimates of body composition in male weight trainers

Journal of Applied Physiology ◽

10.1152/jappl.1996.80.6.2085 ◽

1996 ◽

Vol 80 (6) ◽

pp. 2085-2096 ◽

Cited By ~ 47

Author(s):

C. M. Modlesky ◽

K. J. Cureton ◽

R. D. Lewis ◽

B. M. Prior ◽

M. A. Sloniger ◽

...

Keyword(s):

White Men ◽

Dual Energy ◽

Fat Free Mass ◽

Whole Body ◽

Body Density ◽

X Ray ◽

Musculoskeletal Development ◽

Four Component Model ◽

Weight Trainers ◽

Deuterium Dilution

The purpose of this study was to determine whether the assumed density and composition of the fat-free mass (FFM) and estimates of percent fat (%Fat) from body density by use of the Siri equation (%Fatd) are valid in weight trainers with high musculoskeletal development. Measures of body density by underwater weighing (Db), body water by deuterium dilution, and bone mineral by whole body dual-energy X-ray absorptiometry were obtained in young white men: 14 weight trainers with high musculoskeletal development and 14 non-weight-training controls with average musculoskeletal development. %Fatd was significantly higher (P < or = 0.05) than %Fat estimated from body density, water, and mineral (%Fatd,w,m) by use of a four-component model in weight trainers (17.3 +/- 4.6 vs. 13.2 +/- 5.1%) but not in controls (14.8 +/- 3.1 vs. 14.2 +/- 3.6%). The greater discrepancy between %Fatd and %Fatd,w,m was explained by lower density of fat-free mass (Dffm) in weight trainers (1.089 +/- 0.005 g/ml) than in controls (1.099 +/- 0.007 g/ml). The lower Dffm in the weight trainers was due to higher water (74.8 +/- 1.2 vs. 72.6 +/- 20%) and lower mineral (5.3 +/- 0.6 vs. 5.9 +/- 0.4%) and protein (19.9 +/- 1.4 vs. 21.5 +/- 1.9%) fractions of the FFM. We conclude that, in young white men with high musculoskeletal development, Dffm is lower than the assumed value of 1.1 g/ml and %Fat is overestimated from Db by use of the Siri equation.

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Evaluation of a model for total body protein mass based on dual-energy X-ray absorptiometry: comparison with a reference four-component model

British Journal Of Nutrition ◽

10.1079/bjn2001387 ◽

2001 ◽

Vol 86 (1) ◽

pp. 45-52 ◽

Cited By ~ 21

Author(s):

N. J. Fuller ◽

J. C. K. Wells ◽

M. Elia

Keyword(s):

Dual Energy ◽

Fat Free Mass ◽

Component Model ◽

Body Volume ◽

Body Protein ◽

X Ray ◽

Protein Mass ◽

Four Component Model ◽

The Mean ◽

Total Body

The aim of the present study was to evaluate a model of body composition for assessing total body protein (TBP) mass using dual-energy X-ray absorptiometry (DXA), with either measured or assumed total body water (TBW); it was intended to provide a less complex or demanding alternative technique to, for example, the four-component model (4-CM). The following measurements were obtained in healthy adults (n46) aged 18–62 years, and children (n30) aged 8–12 years: body weight (BWt), body volume (BV; under-water weighing), TBW (2H-dilution space or predicted using an assumed hydration fraction of fat-free mass (HFffm)), bone mineral content (BMC; DXA) and fat-free soft tissue (FFST; DXA). TBP was calculated using the 4-CM (TBP=3·050BWt-0·290TBW-2·734BMC-2·747BV) and the DXA model (TBP=FFST-0·2305BMC-TBW). DXA measurements were obtained using the Lunar DPX (Lunar Radiation Corporation, Madison, WI, USA) or Hologic QDR 1000/W (Hologic, Waltham, MA, USA). Precision of the DXA model for TBP with measured TBW (4·6–6·8 % mean TBP) was slightly worse than the 4-CM (4·0–5·4 %), whereas that modelled with assumed HFffmwas more precise (2·4–5·2 %) because it obviated imprecision associated with measuring TBW. Agreement between the 4-CM and DXA model with measured TBW was also worse (e.g. bias, 15 % of the mean; 95 % limits of agreement up to ±39 % for adults measured on the Lunar DPX) than when a constant for HFffmwas assumed (3·7 % and ±21 % respectively). Most of the variability in agreement between these various models was due to interpretation of biological factors, rather than to measurement imprecision. Therefore, the DXA model, which is less complex and demanding than the 4-CM, is of value for assessing TBP in groups of healthy subjects, but is of less value for individuals in whom there may be substantial differences from reference 4-CM estimates.

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Four-Component Model of Body Composition in Chronic Renal Failure Comprising Dual-Energy X-ray Absorptiometry and Measurement of Total Body Water by Deuterium Oxide Dilution

Clinical Science ◽

10.1042/cs0910763 ◽

1996 ◽

Vol 91 (6) ◽

pp. 763-769 ◽

Cited By ~ 13

Author(s):

Graham Woodrow ◽

Brian Oldroyd ◽

John H. Turney ◽

Peter S. W. Davies ◽

Janice M. E. Day ◽

...

Keyword(s):

Renal Failure ◽

Chronic Renal Failure ◽

Total Body Water ◽

Dual Energy ◽

Body Water ◽

Fat Free Mass ◽

Component Model ◽

X Ray ◽

Four Component Model ◽

Total Body

1. Assessment of nutrition in patients with chronic renal failure by body composition measurement techniques may be affected by variable hydration. 2. This study aimed to derive a four-component model of body composition (consisting of fat, protein, total body water and body mineral) from a combination of dual-energy X-ray absorptiometry and total body water measured by deuterium oxide dilution, allowing assessment of body protein stores without the effect of variation in hydration. Patients with chronic renal failure on haemodialysis, peritoneal dialysis and conservative treatment and a control group were studied. Patients with chronic renal failure were at an ‘ideal’ state of hydration on clinical assessment. 3. Hydration was defined by total body water as a percentage of fat-free mass measured by dual-energy X-ray absorptiometry, and no differences were found between chronic renal failure subgroups and control subjects (except in the female undialysed chronic renal failure subgroup). Hydration was significantly correlated with percentage total body fat in the control groups but not in patients with chronic renal failure. 4. Lean tissue measured by dual-energy X-ray absorptiometry was significantly reduced in three of the six chronic renal failure groups compared with control subjects (male and female patients on haemodialysis and female patients on peritoneal dialysis). Protein estimated from the four-component model failed to detect these abnormalities. 5. Lean tissue measured by dual-energy X-ray absorptiometry in normal subjects strongly correlated with fat-free mass measured by total body potassium in normal subjects (male r = 0.91; female r = 0.89, both P < 0.0001). The correlation of protein estimated from the four-component model with fat-free mass measured by total body potassium was far weaker in male control subjects (r = 0.51, P < 0.05) and not significant in female control subjects (r = 0.38, P not significant). In the normal subjects protein estimated from the four-component model showed a much greater variation from protein estimated by total body potassium than did protein estimated simply as 27% of dual-energy X-ray absorptiometry fat-free mass minus total body mineral. 6. Hydration in patients with chronic renal failure in whom fluid balance is believed to be normal on clinical criteria does not differ from that in normal subjects. The combined model of dual-energy X-ray absorptiometry and total body water is not a useful method for the measurement of body protein.

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