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PubMed1997

Body composition changes in chronic hemodialysis patients before and after hemodialysis as assessed by dual-energy x-ray absorptiometry.

The aim of this study was to investigate the effect of hemodialysis on body composition assessment by dual-energy x-ray absorptiometry (DEXA). Seventeen patients with chronic renal failure who were on a regular hemodialysis schedule were studied. Body weight and body composition were assessed immediately before and approximately 1 hour after a typical hemodialysis session. Body weight was assessed by means of an electronic balance. Body composition measurements were made by DEXA. Whole-body and subtotal (head and neck excluded) analysis assessed the following parameters: body weight, bone mineral density (BMD), bone mineral content (BMC), and fat (FTM) and lean (LTM) tissue mass. BMC, FTM, and LTM were estimated separately for the trunk, arms, and legs. The mean body weight reduction after hemodialysis was 2.8 +/- 1.1 kg (mean +/- SD). Concerning whole-body analysis, no change was observed in mean BMC and FTM after hemodialysis. On the contrary, a significant reduction was observed in mean body weight as assessed by DEXA (before hemodialysis, 65.0 +/- 11.4 kg; after, 62.2 +/- 10.9 kg, P = .0003), as well as in mean LTM (before hemodialysis, 42.7 +/- 9.4 kg; after, 39.7 +/- 9.0 kg, P = .0003). Similar results were obtained from subtotal and regional analysis. Body weight changes as measured by the electronic balance exhibited a strong positive correlation with the changes in both body weight and LTM as assessed by DEXA (r = .989, standard error of the estimate [SEE] = 0.167 kg and r = .941, SEE = 0.382 kg, respectively, P < .0001). It is concluded that gravimetric changes induced by hemodialysis are highly correlated with LTM changes and are not associated with changes in BMC or FTM estimated by DEXA.

Absorptiometry, Photon↗

PubMed2000

Body composition and dietary intake in relation to drug abuse in a cohort of HIV-positive persons.

We examined the relationships between drug abuse, weight, body composition, and dietary intake in persons infected with HIV in a cross-sectional analysis of baseline data from a longitudinal study of nutritional status and HIV. Body composition was measured by bioelectrical impedance analysis. Dietary data were collected by 3-day food records or 24-hour recalls. We analyzed data from 39 current intravenous drug users (IVDU), 103 past intravenous drug users (past-IVDU), 239 users of nonintravenous drugs (users-NIVD), and 61 nonusers (reference category). In the men, there were no differences in weight, body mass index (BMI), or body composition among the drug-use groups. In the women, there was a trend to lower weight and BMI across the drug use categories: IVDU women had lower average weight (-13.7 kg; p = .006), BMI (-5.6 units; p = .003) and less fat mass than non-users (-9.8 kg; p = .0001). In women, drug users had higher weight-adjusted energy intakes than nonusers, whereas in the men both drug using groups, NIVD and IVDU, had higher energy intakes than nonusers. These data suggest that intravenous drug-abuse is associated with lower weight and fat mass in women with HIV infection despite adequate self-reported energy intake.

Adult↗

PubMed1994

Body composition in white adults by dual-energy x-ray absorptiometry, densitometry, and total body water.

Percent body fat (%BF) and fat-free mass (FFM) were determined in 151 adults from the Fels Longitudinal Study by total body scans with a Lunar DPX (DXA), by underwater weighing and residual lung volume with a two-compartment model using body density (Dens), and total body water (TBW) using deuterium dilution. For the DPX, the medium scan mode ensures precision up to 100 kg body wt and for a ratio of weight to stature < or = 0.7214. Because of these specifications, 15% (n = 23) of the original sample of 151 were excluded. Results for 78 women and 50 men are presented. %BFTBW was significantly (P < 0.05) less than %BFDens in women (mean difference 2.7 +/- 4.2%) and %BFDXA in men (mean difference 2.2 +/- 4.3%). No other significant intermethod differences were observed for %BF and FFM estimates. Pairwise regressions showed the lowest SEEs for %BFDens regressed vs %BFDXA (2.3% for men, 3.2% for women) and for FFMDens vs FFMDXA (2.2 kg for men, 1.9 kg for women). For each sex, reliability analyses and limits of agreement for body composition estimates showed less agreement between TBW and either Dens and DXA than between Dens and DXA.

Absorptiometry, Photon↗

PubMed2003

Medium- versus long-chain triglycerides for 27 days increases fat oxidation and energy expenditure without resulting in changes in body composition in overweight women.

OBJECTIVE: To determine the effects of long-term consumption of medium chain (MCT) versus long chain triglycerides (LCT) on energy expenditure (EE), substrate oxidation and body composition. HYPOTHESIS: MCT consumption will not result in greater EE, substrate oxidation, and body weight loss compared with LCT consumption. RESEARCH METHODS AND PROCEDURES: Seventeen healthy obese women participated in this randomized, crossover inpatient trial. Meals were prepared and consumed on site for two periods of 27 days. Diets containing 40% of energy as fat, with treatment fat comprising 75% of the total fat, were designed to supply each subject with their individual weight-maintaining energy needs. The MCT diet contained 67% of treatment fat as MCT oil (49% octanoate, 50% decanoate) whereas the LCT diet contained exclusively beef tallow as treatment fat. Body composition was assessed by magnetic resonance imaging (MRI) on day 1 and 28 of each phase while energy expenditure was measured on day 2 and 27. RESULTS: Changes in total and subcutaneous adipose tissue volumes following consumption of MCT and LCT were not different (-0.61+/-0.38 l vs -0.54+/-0.48 l and -0.58+/-0.35 l vs -0.48+/-0.40 l, respectively). Average EE and fat oxidation were greater (P<0.05) during MCT than LCT consumption (0.95+/-0.019 vs 0.90+/-0.024 kcal/min, respectively, for EE and 0.080+/-0.0026 vs 0.075+/-0.0022 g/min, respectively for fat oxidation). DISCUSSION: These results show that long-term consumption of MCT enhances EE and fat oxidation in obese women, when compared to LCT consumption. The difference in body composition change between MCT and LCT consumption, although not statistically different, was consistent with differences predicted by the shifts in EE. It can be concluded that substitution of MCT for LCT in a targeted energy balance diet may prevent long-term weight gain via increased EE.

Adipose Tissue↗

PubMed1997

Estimation of body composition in competitive swimmers by means of three different techniques.

Up to now controversial reports have been published in regard to the beneficial effects of swimming, a non-weight-bearing activity, on bone mass (BM). Therefore, the aim of this study was to investigate the effects of competitive swimming practice on the bone mineral density (BMD) and bone mineral content (BMC) as well as on the different factors of body composition. For this purpose, competitive swimmers (16 males and 16 females) were selected as subjects in order to investigate the influence of swimming on the three main factors of body composition (BMC, lean body mass [LBM] and body fat [BF]) of the human body. The latter were estimated using three different approaches: the skinfold, the dual energy x-ray absorptiometry (DEXA) and the whole body potassium (K-40) methods. Since BM and LBM are also related, the possible correlations between shoulder strength (extensions and flexion movements) and performance with BMD, BMC, LBM and BF were also investigated. Our results showed that BMD was not affected by swimming exercise since z (%) values were similar between swimmers and their respective age-matched controls. Swimmers also showed lower BF and increased LBM in the region of upper extremities (arms and trunk) as compared to their lower extremities (legs), a finding which is typical for the sport they are trained for. Also, comparison between sexes showed that males had a more central distribution of fat when compared to females, in which BF was built up in the region of legs. Furthermore, shoulder strength and performance were significantly related (p < 0.05) to age, BMC, and LBM while performance was also significantly related (p < 0.05) to all the other BM indices. So, mineralization of the bone is important for shoulder muscular strength which is subsequently related to performance. We used the DEXA because it enabled the direct estimation of the three factors of body composition (BM, BF and LBM).

Absorptiometry, Photon↗

PubMed1998

Leptin and body composition of Nigerians, Jamaicans, and US blacks.

The role of leptin in humans remains controversial. Leptin concentrations are highly correlated with body fat stores. We tested whether or not this relation was consistent across the range of body composition encompassing the lean as well as the obese. Individuals participating in community-based comparative research in Nigeria (n = 363), Jamaica (n = 372), and the United States (Maywood, IL; n = 699) had their plasma leptin concentrations and body compositions (with bioelectrical impedance analysis) measured. All participants identified themselves as being black. Body mass index (in kg/m2) ranged from 14 to 62. Large differences in mean plasma leptin were noted across populations for both men and women in Nigeria, Jamaica, and the United States, respectively (men: 2.8, 3.9, and 6.8 microg/L; women: 10.3, 18.6, and 27.7 microg/L). An exponential function fit the relation between percentage body fat or total fat mass and leptin for men and women at each site. For women and men the exponential function with either percentage body fat or total fat mass was of the same shape, but increased by a constant in women, yielding higher leptin concentrations than in men at every level of body fat. On the basis of this broad distribution of body composition, the data suggest an exponential response of leptin to increases in body fat stores, consistent with the development of leptin resistance in individuals developing obesity. These findings likewise confirm that men and women exhibit different set points in terms of leptin production.

Adipose Tissue↗

PubMed1998

Body composition analysis of small pigs by dual-energy x-ray absorptiometry.

We evaluated the use of dual-energy x-ray absorptiometry (DXA) for measuring the gross body composition of small subjects in 97 pigs that ranged from 5 to 27 kg live body weight. Scans were performed using a Lunar DPXL densitometer in the pediatric mode (Version 3.8e). The DXA scans of the live pigs provided measurements of total fat, lean, and bone mineral content. After scanning, the pigs were killed, the entire body was ground, and samples were analyzed chemically (CHEM) for fat, protein, ash, and water content. We found that DXA significantly underestimated the percentage of fat in the body (DXA, 6.9+/-.33% vs CHEM, 10.9+/-.31%, P < .001). The correlation (r) between DXA and chemical measures of percentage fat was .86 and for grams of fat it was .96. Lean tissue mass measured by DXA was highly correlated with CHEM measurements of total grams of body water (r = .99), total grams of body protein (r = .94), and lean body mass (r = .99). The average DXA bone mineral content was within 2% of the amount estimated from total body ash and the correlation between the two values was .94. The relationships between DXA and CHEM measurements for percentages of body composition of pigs that weighed between 5 and 27 kg are described by the following regression equations: %fatCHEM = 5.22 + [.817.fatDXA], (r = .86, standard error of the estimate, SEE = 1.56); %proteinCHEM = -7.8 + [.256%leanDXA], (r = .35, SEE = 2.3); %waterCHEM = -5.2 + [.808-%leanDXA], (r = .59, SEE = 3.67). These results are consistent with previously reported results and suggest that even though direct use of DXA readings may not be sufficiently accurate, the high degree of correlation indicates that with proper calibration the DXA values can be used to predict body composition.

Absorptiometry, Photon↗

PubMed1997

Body composition of a young, multiethnic, male population.

The study objective was to establish the range of total body-composition values for a young, multiethnic, healthy male population (aged 3-18 y) by using dual-energy X-ray absorptiometry (DXA). Results for 297 males in three ethnic groups [European American (white), n = 145; African American (black), n = 78; and Mexican American (Hispanic), n = 74] are reported. Bone mineral content (BMC), lean tissue mass (LTM), body fat mass, and percentage fat are presented as functions of age. Analysis of variance with age, weight, and height as covariates was used to evaluate differences among the three ethnic groups. BMC and LTM were higher in black than in white males, but no difference in BMC or LTM was evident between the white and Hispanic groups. The relation between total-body BMC and LTM was linear (r = 0.985, P < 0.0001) and independent of age or ethnic classification. The Hispanic males had higher body fat values than the white group, whereas the black males generally had lower values than the white group. When adjusted for body size, the Hispanic males continued to have significantly higher body fat and percentage fat than the white or black males. Ethnic-specific equations for the prediction of body composition as a function of age, weight, and height were derived. The results for the white males in the present study were compared with DXA-derived reference data reported in other countries for young white males. We conclude that reference values of total body composition for young healthy males need to be ethnic specific.

Absorptiometry, Photon↗

PubMed2001

Assessment of body composition by bioelectrical impedance analysis without the need for measurement of height.

Conventional whole-body single frequency bioelectrical impedance analysis (BIA) of body composition typically uses height as a surrogate measure of conductor length. A new method of BIA analysis for the prediction of body cell mass (BCM) and extracellular water (ECW, as % body weight) not using height has been introduced-the Soft Tissue Analyser (STA(TM), Akern Sri, Florence, Italy)-making it ideal for use in subjects where measurement of height is difficult or impossible. The performance of the new analytical method in predicting BCM and ECW in 139 normal control subjects was assessed by comparison with reference data obtained from a four-component (4-C) model of body composition and with predictions obtained from conventional BIA analysis. Both predicted BCM and ECW were strongly (r=0.82, SEE=6.3 kg and 0.89, SEE=1.3 kg respectively) correlated with the corresponding 4-C model measurements although differing significantly from the lines of identity (P<0.0001). Fat-free mass, calculated from STA estimates of BCM and ECW, was better predicted (r=0.91, SEE=5.6 kg). The significant differences in STA-group mean values for BCM and ECW and wide limits of agreement compared with the reference data indicate that the method cannot be used with confidence for prediction of these body compartments despite the obvious advantage of not requiring an accurate measurement of height.

Adult↗

PubMed1994

Diet and body composition of preterm infants.

There have been few systematic studies of the effects of energy and protein intake on the body composition of preterm infants. Analysis of published studies suggests a roughly inverse relation between energy stored per gram of weight gain (a measure of the fatness of new tissues) and the ratio of protein to energy in the preterm infant's diet. At least within a certain range of energy and protein intakes, a higher protein diet promotes leaner body composition. Studies of the effects of varying the dietary ratio of carbohydrate to fat in preterm infants have shown reduced rates of carbon dioxide production with high-fat diets, fed by either the parenteral or enteral route. The little information available suggests no clear effect of varying the carbohydrate-to-fat ratio on body composition. The mineral content of the body can be influenced by diet. Insufficient intakes of calcium and phosphorus reduce the bone mineral content and thus the whole-body content of these minerals.

Body Composition↗

PubMed1993

Assessment of body composition with use of dual-energy x-ray absorptiometry: evaluation and comparison with other methods.

Dual-energy x-ray absorptiometry (DEXA) is a relatively new method of assessing body composition in humans. In the current study, DEXA was analyzed for accuracy and precision by using both anthropomorphic phantoms and a combination of body composition techniques in humans. Satisfactory precision for measurement of total body fat, fat-free mass, and total body bone mineral could be demonstrated in vivo and in vitro. Predictions of lean body mass in humans on the basis of DEXA, total body water, and total body potassium were significantly different. The results of multiple regression analysis suggested that a component of total body water was related to body potassium, and another component was predicted by body fat. In addition, extracellular fluid volume, as measured by the bromide space technique, was significantly associated with both fat-free mass and fat mass as measured by DEXA. These findings have implications for the interpretation of body composition data in humans.

Absorptiometry, Photon↗

PubMed1994

Effects of growth hormone treatment for short stature on calcium homeostasis, bone mineralisation, and body composition.

We investigated the effect of growth hormone (GH) treatment on mineral and vitamin D homeostasis, bone mineralisation, and body composition in short-statured children without GH deficiency (GHD). 11 children received GH (0.50 +/- 0.08 IU/kg/week) for 24 weeks. 1,25-Dihydroxyvitamin D3 levels (mean +/- SD in pmol/l) rose from a baseline of 73.7 +/- 39.2 to 114.0 +/- 32.7 at 8 weeks (p < 0.05) and 111.9 +/- 39.7 at 24 weeks (p < 0.01). Body composition evaluation using dual-energy X-ray absorptiometry revealed increased lean tissue mass and a reduction in fat tissue. As a percentage of total body mass, fat decreased from 19.0 +/- 11.8% at baseline to 17.3 +/- 11.5% at 8 weeks (p < 0.005) and 16.8 +/- 11.5% at 24 weeks (p < 0.05). L2-L4 bone mineral density was 0.637 +/- 0.155 g/cm2 at baseline and 0.666 +/- 0.160 g/cm2 at 24 weeks (NS). We conclude that recombinant human GH treatment of short children without GHD has significant effects on vitamin D homeostasis and body composition.

Body Composition↗

PubMed1987

Body composition and physiological characteristics of law enforcement officers.

The physical work capacity, body composition, and physiological characteristics of 12 law enforcement officers (9 males, 3 females) were measured. Subjects included a representative sample from the occupational categories of detective, staff, investigative and patrol officer. Mean maximal oxygen uptake of the men was 42.1 +/- 8.9 ml.kg-1min-1 with mean values of 41.5 +/- 8.7 ml.kg-1min-1 for the women. Measurement of body composition indicated an average of 24.4 +/- 7.1% body fat for the men and 30.9 +/- 1.2% for the women. Muscular power, strength, and endurance as measured by isolated limb flexion-extension movement and fitness test performance was considered average with no excessive bilateral differences. The results of this study were compared with other investigations of law enforcement officers of similar age groups. The officers displayed average or above health and physical fitness scores for their age classification and were able to complete all police task-oriented tests.

Adult↗

PubMed1978

[Effect of diet and thyroxine on body composition in rats].

In young male Wistar rats the influence of different fat content of the diet (7 or 25 or 50 weight percent of fat) and of thyroxine (5 or 50 microgram/100 g body mass, 2 times/week, sc.) on body composition was investigated by carcass analysis. After high doses of thyroxine the percentage body fat decreases and protein and water content increases within the same diet group (7 or 25 or 50% fat diet). Smaller doses of thyroxine have only the same effect as high thyroxine doses in the 7% fat diet group; the body composition is unchanged in the 25% fat diet group, and in rats after 50% fat diet thyroxine even brings about an increase in body fat. It is concluded that the fat content of the diet makes thyroxine partly ineffective. A comparison of the different diet groups, also with or without thyroxine treatment, brings the result of significantly increased percentage body fat after 25 and 50% fat diet; body protein and body water decreases respectively. It appears from the present study that controversial results in literature concerning body composition after thyroxine treatment, may be caused by different diets, especially the fat content of the diets.

Animals↗

PubMed1998

Body composition assessment by dual-energy x-ray absorptiometry: comparison of prone and supine measurements.

The aim of the study was to assess whether changes in the interposition of body compartments affect the results of body composition measurements by dual-energy x-ray absorptiometry (DEXA) in the fan-beam mode. Thirty healthy subjects underwent two sequential measurements: the first was performed in the supine position as described by the manufacturer, and the second in the prone position. Estimates of body composition were compared between the two measurements. Mean body weight did not differ between measurements ([mean+/-SD] supine vprone, 68.561+/-12.461 v 68.589+/-12.469 kg). Mean bone mineral content (BMC) was lower in the prone position versus the supine position. When the head was excluded, this difference reached statistical significance (supine v prone, 1,738+/-361 v 1,688+/-360 g, P=.0001). The mean fat tissue mass (FTM) was lower and lean tissue mass (LTM) higher in the prone measurements. When the head was excluded, the mean FTM difference between the two measurements became greater (FTM supine v prone, 25.129+/-10.445 v 24.030+/-10.388 kg, P=.0001; LTM supine v prone, 37.309+/-9.357 v 38.246+/-9.150 kg, P=.0001). It is concluded that the positioning of the patient on the examination table affects DEXA body composition measurements by the fan-beam mode. This could imply a lack of accuracy of the method, which may be due to subtle changes in regional tissue depth and fat distribution caused by patient repositioning.

Absorptiometry, Photon↗

PubMed2003

Effects of body size and body composition on survival in hemodialysis patients.

It is unclear whether increased muscle mass or body fat confer the survival advantage in hemodialysis patients with high body-mass index (BMI). Twenty-four-hour urinary creatinine (UCr) excretion was used as a measure of muscle mass. The outcomes of hemodialysis patients with high BMI and normal or high muscle mass (inferred low body fat) and high BMI and low muscle mass (inferred high body fat) were studied to study the effects of body composition on outcomes. In 70,028 patients who initiated hemodialysis in the United States from January 1995 to December 1999 with measured creatinine clearances reported in the Medical Evidence form, all-cause and cardiovascular mortality were examined in Cox and parametric survival models. When compared with normal BMI (18.5 to 24.9 kg/m(2)) group, patients with high BMI (> or = 25 kg/m(2)) had lower hazard of death (hazard ratio [HR], 0.85; P < 0.001). However, when compared with normal BMI patients with UCr >25th percentile (0.55 g/d), high BMI patients with UCr >0.55 g/d had lower hazard of all-cause (HR, 0.85; P < 0.001) and cardiovascular death (HR, 0.89; P < 0.001), and high BMI patients with UCr < or =0.55 g/d had higher hazard of all-cause death (HR, 1.14; P<0.001) and cardiovascular death (HR, 1.19; P <0.001). Both BMI and body composition are strong predictors of death. The protective effect conferred by high BMI is limited to those patients with normal or high muscle mass. High BMI patients with inferred high body fat have increased and not decreased mortality.

Aged↗

PubMed2000

Bone mineral density and body composition in patients with ulcerative colitis.

OBJECTIVE: Reduced bone mineral density (BMD) has been reported in ulcerative colitis (UC) patients, but body composition (fat and lean mass) has never been concomitantly studied. We sought to investigate BMD and body composition in a group of UC outpatients with the following characteristics: age 18-60 yr (men) and 18-45 yr (women); no intestinal resection; no immunosuppressive treatment; and regular menstruation. METHODS: Whole body and subregional BMD and body composition in 43 UC patients (21 men, 22 women; male mean age, 36.5 [21-57] yr; female mean age, 35.3 [23-45] yr) and 121 healthy volunteers were studied by means of dual X-ray photon absorptiometry. RESULTS: There were no differences in total and subregional BMD, or fat and lean mass between the patients and controls, except that the total and trunk lean mass of the UC women was lower than that in the normal controls. No correlation was found between lifetime steroid intake and BMD. CONCLUSIONS: UC outpatients do not differ from normal subjects in terms of BMD and fat mass. Mild and moderate UC does not represent a risk factor for osteopenia.

Absorptiometry, Photon↗

PubMed1993

Determination of body composition--a comparison of dual-energy x-ray absorptiometry and hydrodensitometry.

Determination of body composition by dual-energy x-ray absorptiometry (DEXA) was evaluated in healthy men, by using underwater weighing (UWW), skinfold thickness measurement, and bioimpedance analysis. There were strong correlations between percent body fat obtained by all techniques, but DEXA gave significantly lower values (P < 0.001). The influence of differences in bone mineral density (BMD) on fat content determined by UWW was also studied. The individual differences between UWW and DEXA fat estimates were calculated and there was a negative correlation with BMD (r = -0.50, P < 0.05). There was also a negative correlation between body fat by UWW and BMD (r = -0.71, P < 0.01) in the subjects with lowest fat by DEXA, indicating that high or low BMD gave false values by UWW. In conclusion, DEXA and UWW provide complementary information and a combination of these techniques seems to offer new opportunities in evaluations of body composition.

Absorptiometry, Photon↗