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PubMed1989

Body composition in children: proposal for a method for calculating body fat percentage from total body density or skinfold-thickness measurements.

A method is presented for assessing childhood obesity in a more objective way than most other routine methods used for diagnosing childhood obesity. The sum of bicipital, tricipital, subscapular, and suprailiacal skinfold thicknesses is related to total body density by use of theoretically defined prediction equations. Total body density is used to estimate total body fat percentage by use of age- and sex-dependent equations on the relation between body fat percentage and body density. These equations are constructed on the basis of published data on changes in the density of fat-free mass with age in children. With the proposed method childhood obesity can be assessed routinely in a more consistent way than with most other routine methods used to diagnose obesity in children. A preliminary validation study indicated that in children aged 7-10 y predicted body density differed on average less than 1% from measured body density. In addition, predicted body density was highly correlated (r greater than 0.7) with measured body density.

Adipose Tissue↗
PubMed1993

Early changes of body composition in human immunodeficiency virus-infected patients: tetrapolar body impedance analysis indicates significant malnutrition.

Total body water, body fat, body cell mass (BCM), extracellular mass (ECM), and the ECM-BCM ratio by impedance analysis were determined in 193 human immunodeficiency virus (HIV)-infected patients and 340 control subjects. Walter Reed (WR) classification was WR 2 in 26, WR 3-5 in 85, and WR 6 in 82 patients. Whereas resistance was increased, reactance and the phase angle were significantly reduced in all patient groups. Neither body weight nor body mass index (BMI) was affected in WR 2 patients, but BCM was reduced (31.9 +/- 4.3 vs 35.8 +/- 7.3 kg, P < 0.007) and ECM (31.2 +/- 4.4 vs 28.8 +/- 3.8 kg) as well as ECM-BCM ratio increased (0.99 +/- 0.14 vs 0.83 +/- 0.16, P < 0.001). In contrast to WR classification, diarrhea did not correspond with malnutrition. A loss of BCM (malnutrition) occurred already in otherwise symptomless HIV-infected patients (WR 2). This effect can be measured by tetrapolar impedence analysis but not by body weight or BMI.

Adult↗
PubMed2001

Body composition estimates from multicomponent models using BIA to determine body water.

PURPOSE: The purpose of this study was to compare estimates of body fat (%BF) from three- and four-component models with total body water (TBW) determined by single-frequency bioelectrical impedance analysis (BIA; %BF3C-BIA and %BF4C-BIA) to %BF estimates from densitometry (%BF2C-D) and from three- and four-component models with TBW determined using deuterium dilution (%BF3C-D2O and %BF4C-D2O), the criterion methods. METHODS: Measures of body density by hydrostatic weighing, TBW by BIA and D2O dilution, and bone mineral by dual energy x-ray absorptiometry (DXA) were obtained in 40 men and 93 women, 18-42 yr. TBW was estimated from BIA resistance (RJL analyzer) using an equation developed and cross-validated in two independent samples. Body fat was estimated using the three-component model of Siri (1961) and a four-component model modified from Lohman (1986). RESULTS: There was a strong relation and no significant difference between TBW estimated by BIA and D2O [r = 0.94, SEE = 2.4; xDiff = 0.0 +/- 2.4 L (SD), P > 0.05]. There were strong relations between methods for estimating %BF, with deviations from %BF4C-D2O (errors) for %BF3C-BIA [r = 0.99, SEE = 2.4% BF, xDiff = -0.4 +/- 2.4% BF (SD)] and %BF4C-BIA [r = 0.99, SEE = 2.3% BF, xDiff = 0.2 +/- 2.3% BF (SD)] being nonsignificant (P > 0.05) although greater than for %BF3C-D2O [r = 1.00, SEE = 0.5% BF, xDiff = -0.6 +/- 0.5% BF (SD)], and comparable or slightly worse than for %BF2C-D [r = 0.99, SEE = 2.3% BF, xDiff = 0.4 +/- 2.3% BF (SD)]. CONCLUSIONS: We conclude that because estimates of %BF from multicomponent models with TBW estimated from BIA are not more accurate than from body density alone using a two-component model, estimates of %BF from three- and four-component models using TBWBIA are not acceptable substitutes for estimates from the same models using TBWD2O.

Adipose Tissue↗
PubMed2006

[The effect of an exercise program on body composition and physical fitness in obese female college students].

PURPOSE: This study was done to analyze the effects of an exercise program on body composition and physical fitness of obese female college students. METHOD: Data was collected from September 29, 2003 to December, 29, 2003. The research design was a randomized control group pretest-posttest experimental design. The subjects were college nursing students at K University. Forty four students, 20 in the experimental group and 24 ina control group, with more than 30% body fat were randomly assigned. The subjects in the experimental group participated in an exercise program for 12 weeks, sixty minutes per session, five times per week. Body composition and physical fitness was measured by a body composition analyzer, cardiovascular endurance, muscle endurance, muscle strength(grip strength, back strength), flexibility, balance, agility(whole body reaction time) and power(standing long jump). RESULT: Body weight(F=4.76, p=0.035), body fat(kg)(F=5.68, p=0.022) and body mass index(F=5.73, p=0.021) of the experimental group were significantly different from the control group, but there were no significant differences in body fat(%), lean body mass, muscle mass and WHR. Back strength(F=6.50, p=0.015), flexibility(F=14.62, p=0.000), muscle endurance(F=7.98, p=0.007), power(F=5.76, p=0.021) and balance(F=2.46, p=0.018) of the experimental group were significantly different from the control group, but there were no significant differences in cardiovascular endurance, grip strength or agility. CONCLUSION: The exercise program was effective in improving body weight, body fat(kg), body mass index, back strength, muscle endurance, flexibility, balance and power of obese female college students.

Adolescent↗
PubMed1982

Body composition and resting metabolic rate: the myth of feminine metabolism.

Resting metabolic rate (RMR) in adults can be viewed from two perspectives. Body surface area is used to index RMR in the clinical perspective. Normal values of RMR are thus sex-specific and appear to be lower in women. However, the physiological perspective is one of an asexual metabolism that differs in the mass of active cells. The body cell mass is relatively reduced in women due to a smaller skeletal muscle mass in tandem with a greater fat mass. RMR is proportionately reduced and thus highly correlated with body cell mass or lean body mass in mixed sex data. Athletic training can negate the differences in body composition and RMR per unit weight. The body mass index is another nonphysiological and sex-specific parameter currently being applied to obesity research. The clinical utility of body surface area for the prediction of RMR results from its correlation with body composition within either sex. The clinical and physiological perspectives of RMR must be clearly distinguished and treated as distinct.

Adult↗
PubMed1998

Use of magnetic resonance in body composition studies: applications to research on caloric restriction and exercise.

Applications of magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) in studies of body composition are discussed. MRI is an accurate method for volume quantification of lean and adipose tissue in the human body, while MRS is used to study in vivo metabolism of soft tissues. In particular, combination of MRI and phosphorus (31P) MRS, used to asses muscle energy metabolism, may be of great importance in body composition studies. Examples of use of MRI and 31P MRS in studying the effect of caloric restriction on body composition and skeletal muscle metabolism are given.

Body Composition↗
PubMed2006

Amenorrhea after weight recover in anorexia nervosa: role of body composition and endocrine abnormalities.

UNLABELLED: Hypothalamic amenorrhea in anorexia nervosa often precedes weight loss and may persist after re-feeding and restoration of a stable normal weight. AIM: To assess the rate of persistent amenorrhea in anorexia nervosa (AN) after re-feeding and the relations of this condition with body composition changes and other endocrine parameters. METHODS: A cohort of 250 female outpatients was studied to assess persistent amenorrhea prevalence after stable weight recovery. Among these, we selected 20 AN female patients (age 16.5-35), 10 with amenorrhea (group 1) and 10 with normal menses (group 2). We collected data such as age, age at menarche, age at onset of AN, actual body mass index (BMI) and at onset of AN, duration of disease. Physical activity has been evaluated as minute per day. The following data were obtained: prolactin, growth hormone, estradiol, luteinizing hormone, follicle stimulating hormone, thyroid stimulating hormone, free triiodothyronine, free thyroxine, free urinary cortisol, serum calcium and phosphates, urinary calcium, phosphaturia and alkaline phosphatase. Body composition was assessed with a dual energy x-ray absorptiometry (DEXA). RESULTS: Thirty-five patients (14%) over a cohort of 250 where still amenorrhoic after stable weight recovery. No significance was found in the evaluation of blood biochemical tests of the 2 groups. Free urinary cortisol was significantly higher in amenorrhoic patients (58.14+/-0.4 vs 15.91+/-9.5), p=0.02. The analysis of body composition has shown a percentage of fat of 22.23+/-5.32% in group 1 and of 26.03%+/-9.1% in group 2, respectively, showing no significant differences. Amenorrhoic patients carried on doing a significantly heavier physical activity than eumenorrhoic patients. CONCLUSIONS: An adequate body composition and a well represented fat mass are certainly a necessary but not sufficient condition for the return of the menstrual cycle. Such menstrual cycle recovery would probably need other conditions at present being studied and evaluated to occur, such as secretory patterns of leptin and its correlations with adrenal function.

Adolescent↗
PubMed2002

Reference data for bone density and body composition measured with dual energy x ray absorptiometry in white children and young adults.

AIMS: To obtain normative data on bone mineral density and body composition measured with dual energy x ray absorptiometry (DXA) from early childhood to young adulthood. METHODS: Cross sectional results from 444 healthy white volunteers (4-20 years) in the Netherlands were combined with the results from 198 children who agreed to participate in the follow up study approximately four years later. DXA (Lunar, DPXL) of lumbar spine and total body was performed to assess bone density and body composition. RESULTS: Bone density and lean body mass (LBM) increased with age. Maximal increase in bone density and LBM occurred around the age of 13 years in girls and approximately two years later in boys. Bone density of total body and lumbar spine showed an ongoing slight increase in the third decade. Mean fat percentage in boys remained at 10.5% throughout childhood, but increased in girls. CONCLUSIONS: Most of the skeletal mass in lumbar spine and total body is reached before the end of the second decade, with a slight increase thereafter. This study provides reference values for bone density and body composition measured with DXA for children and young adults.

Absorptiometry, Photon↗
PubMed2004

Growth hormone improves mobility and body composition in infants and toddlers with Prader-Willi syndrome.

OBJECTIVES: To determine the effect of growth hormone (GH) on body composition and motor development in infants and toddlers with Prader-Willi syndrome (PWS). STUDY DESIGN: Twenty-nine subjects with PWS (4-37 months of age) were randomized to GH treatment (1mg/m 2 /day) or observation for 12 months. Percent body fat, lean body mass, and bone mineral density were measured by dual x-ray absorptiometry; energy expenditure was measured by deuterium dilution; and motor constructs of mobility (M) and stability (S) were assessed using the Toddler Infant Motor Evaluation (TIME). RESULTS: GH-treated subjects, compared with controls, demonstrated decreased percent body fat (mean, 22.6% +/- 8.9% vs 28.5% +/- 7.9%; P < .001), increased lean body mass (mean, 9.82 +/- 1.9 kg vs 6.3 +/- 1.9 kg; P < .001), and increased height velocity Z scores (mean, 5. 0 +/- 1.8 vs 1.4 +/- 1.0; P < .001). Patients who began GH before 18 months of age showed higher mobility skill acquisition compared with controls within the same age range (mean increase in raw score, 284 +/- 105 vs 206 +/- 63; P < .05). CONCLUSIONS: GH treatment of infants and toddlers with PWS for 12 months significantly improves body composition and when begun before 18 months of age increases mobility skill acquisition. These results suggest that GH therapy instituted early in life may lessen deterioration of body composition in PWS while also accelerating motor development.

Body Composition↗
PubMed1996

Mechanical and physiologic modifiers and bioelectrical impedance spectrum determinants of body composition.

Fat-free mass and total and percentage body fat were determined by dual-energy X-ray absorptiometry (DXA) and total-body and segmental impedance measures were taken at 16 frequencies from 5 to 1300 kHz in a sample of white men and women aged 18-30 y. Plots of total-body and segmental impedance against frequency for each individual indicated that the general shape of these curves was described by the same mathematical function consisting of three components-ai, bi, and ci,-that contain information derived from the individual measurements of impedance summarized across the spectrum of current frequencies. Total-body and segmental multifrequency impedance were significantly correlated with hemoglobin, hematocrit, and serum sodium, potassium, creatinine, and osmolality. Regression models of body composition with total-body or segmental impedance measures at discrete frequencies or the impedance spectrum variables were similar to corresponding findings for impedance models at 50 kHz. The segmental impedance spectrum variables for total and percentage body fat and the ratios of low- to high-frequency impedance from the trunk were significantly associated with total body fatness as measured by DXA.

Absorptiometry, Photon↗
PubMed2007

Body composition of obese subjects by air displacement plethysmography: The influence of hydration.

OBJECTIVE: We investigated whether air displacement plethysmography (ADP) could detect small changes in body composition of obese subjects with alterations in hydration. RESEARCH METHODS AND PROCEDURES: Ten obese subjects (mean BMI, 39.3 +/- 2.8 kg/m2) entered the ADP chamber without and with oil (1, 2, or 4 liters), water (1, 2, or 4 liters), or mixed (1 liter oil + 1 liter water or 2 liters oil + 2 liters water) loads. Real and measured changes in body composition were compared by regression analysis and Bland-Altman procedures. RESULTS: The ADP-measured changes in volume did not differ from the real values and were strongly correlated with them (r = 0.98). In all cases, loads of differing composition and similar volume led to different values of fat, fat-free mass, and percentage fat. Water was detected as increased fat-free mass only with loads of > or =2 liters, most of the water being falsely detected as increased fat mass. The observed changes were correlated with the real ones for fat mass (r = 0.68; p < 0.0001), fat-free mass (r = 0.66; p < 0.0001), and percentage fat (r = 0.61; p < 0.0001), but fat mass changes were overestimated by approximately 1 kg, and fat-free mass changes were underestimated by approximately 1 kg. This underestimation increased with the highest water loads, as shown by the Bland-Altman plot (r = -0.27; p < 0.05). Percentage fat changes were overestimated by 0.8% (p < 0.001); the magnitude of the error was correlated with the weight of the water load (r = 0.62; p < 0.0001). DISCUSSION: ADP accurately measures changes in body volume, discriminating small changes in body composition. It overestimates changes in adiposity, as most of the increased hydration is detected as an enlarged fat mass.

Adipose Tissue↗
PubMed1997

Cross-sectional and longitudinal evaluation of body composition in men with HIV infection.

Body wasting is an increasingly prevalent AIDS-defining condition and an independent risk factor for mortality in patients infected with HIV. Largely on the basis of studies conducted early in the epidemic, HIV-associated wasting has been assumed to feature a disproportionate loss of lean tissue. We report the results obtained from cross-sectional and longitudinal studies that differ from these earlier observations. In a cross-sectional analysis, weight and body composition determined by dual-energy x-ray absorptiometry and bioelectrical impedance analysis in 32 HIV-infected men with documented weight loss of > or = 10% were compared to those in 46 HIV-positive men without significant weight loss and 32 HIV-negative controls. Fat, lean body mass (LBM), and body cell mass (BCM) were significantly lower in men with weight loss relative to controls (p < 0.001 for fat and BCM; p = 0.01 for LBM). Two thirds of the difference in weight was fat. For the longitudinal analysis, the composition of weight lost over time was evaluated in paired measurements in men grouped by body fat content (<15% or >15%, n = 10 per group). Weight loss in patients with baseline fat of more than 15% was only 16% LBM, but the composition of weight lost in men with baseline fat of less than 15% was 70% LBM. We conclude that progressive decreases in fat and lean tissue occur in men with HIV infection, with the composition of weight lost depending on baseline fat content. These results argue against the widely held notion that HIV-associated wasting is characterized by preservation of fat at the expense of lean tissue.

Adipose Tissue↗
PubMed2000

Comparison of methods for assessing body-composition changes over 1 y in postmenopausal women.

BACKGROUND: Advances in dual-energy X-ray absorptiometry (DXA) software algorithms have improved the accuracy of this method for body-composition measurement. OBJECTIVE: Our objective was to compare the utility of DXA, underwater weighing (UWW), and a multicomponent model (MC) for assessing changes in body composition. DESIGN: : Previously sedentary women aged 40-66 y were randomly assigned to exercise training (ET; n = 36) and no exercise training (NT; n = 40). ET subjects exercised 3 d/wk; NT subjects remained sedentary. Changes in body mass, fat mass, and fat-free mass over 1 y were assessed by the 3 methods. RESULTS: Correlations among methods were significant and large (0.73-0.97). Body weight did not change significantly in either group. In the ET group, fat-free mass increased significantly as assessed by DXA (0.7 +/- 1.0 kg) but changes assessed by MC and UWW were not significant. Changes in fat mass and percentage body fat in the ET group were not significant. SDs for changes in fat mass and percentage body fat, respectively, from DXA were 2.5 kg and 2.7%; for MC, 5.5 kg and 7.1%; and for UWW, 4.4 kg and 5.8%. In the NT group, changes in fat-free mass, fat mass, and percentage body fat were significant (P </= 0.02) as assessed by MC (fat-free mass, -1.5 +/- 3.7 kg; fat mass, 2.3 +/- 4.1 kg; percentage body fat, 2.8 +/- 4.7%) and UWW (fat-free mass, -1.1 +/- 2.5 kg; fat mass, 2.1 +/- 3.6 kg; percentage body fat, 2.5 +/- 3.5%), but changes by DXA were not significant (fat-free mass, 0.2 +/- 1.2 kg; fat mass, 1.0 +/- 3.9 kg; percentage body fat, 0.6 +/- 3.2%). CONCLUSION: DXA was the most sensitive method for assessing small changes in body composition of postmenopausal women.

Absorptiometry, Photon↗
PubMed1983

Effects of body composition on insulin sensitivity.

We studied the effects of body composition and maximal aerobic power on insulin sensitivity in 23 normal-weight, healthy male subjects. Eight were weight lifters, eight were long-distance runners, and seven were untrained controls. In each subject, the percentage of body weight (BW) made up of muscle and fat tissue (% muscle and % fat, respectively), the maximal aerobic power (VO2max), and the tissue sensitivity to insulin were measured. The weight lifters were characterized by 35% higher % muscle as compared with the runners or controls (P less than 0.01). VO2max in the runners was 30-40% higher than in the weight lifters or controls (P less than 0.001). During the euglycemic clamp studies, similar steady-state plasma glucose and insulin levels were achieved in each group. When calculated per total BW, the rate of glucose metabolism (M) was virtually identical in the weight lifters (10.26 +/- 1.02 mg/kg BW/min) and the runners (10.03 +/- 0.86 mg/kg BW/min), and 4045% higher than in the controls (7.10 +/- 0.75 mg/kg BW/min, P less than 0.05). When calculated per muscle mass (Mm), only the runners had a higher than normal rate of glucose metabolism (P less than 0.02). M was directly proportional to% muscle (r = 0.54, P less than 0.01) and inversely related to % fat (r = -0.72, P less than 0.001). The multiple linear regression analysis revealed a highly significant multivariate correlation between M and the combined effect of % muscle, %fat, and VO2max (r = 0.78, P less than 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗