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At least 739 records · Page 41Linked to original sources
PubMed2002

Sleeping metabolic rate in relation to body mass index and body composition.

OBJECTIVES: To determine whether patterns of sleeping metabolic rate (SMR) are altered in obesity. Specifically to determine the relationship between changes in SMR and body weight, body mass index (BMI, kg/m(2)), and fat-free mass (FFM); and to compare resting metabolic rate (RMR) with SMR during different periods of sleep. SUBJECTS: Eighteen healthy, pre-menopausal, obese (BMI >30, n=9) and non-obese (BMI <30, n=9), female subjects (six Caucasians and 12 African-Americans), with an average age of 36 y (range 22-45). MEASUREMENTS: Total energy expenditure (TEE or 24 h EE), metabolic rate (MR), SMR (minimum, average and maximum) and resting metabolic rate (RMR) or resting energy expenditure (REE) measured by human respiratory chamber, and external mechanical work measured by a force platform within the respiratory chamber. Physical activity index (PAL) was derived as TEE/REE. Body composition was determined by dual-energy X-ray absorptiometry (DXA). RESULTS: SMR decreased continuously during sleep and reached its lowest point just before the subject was awakened in the morning by the research staff. Although averages for RMR and SMR were similar, RMR was lower than SMR at the beginning of the sleeping period and higher than SMR in the morning hours. The rate of decrease in SMR was faster with increasing body weight (-0.829, P<0.0001), BMI (correlation factor -0.896, P<0.0001) and FFM (-0.798, P=0.001). The relationship between the slope of SMR decrease and BMI (y=-5 x 10(-6)x(2)+0.0002x-0.0028) is highly significant, with a P-value of <0.0001 and r(2) value of 0.9622. CONCLUSIONS: The rate of decline in metabolic rate during sleep is directly related to body weight, BMI and FFM. Average SMR tends to be lower than RMR in obese subjects and higher than RMR in non-obese subjects.

Absorptiometry, Photon↗
PubMed1975

Body weight and body water in chronic cor pulmonale.

1. Body weight was measured through forty consecutive illnesses in seventeen patients with oedema in association with chronic bronchitis and hypoxia. All patients were taking diuretic drugs at the time. 2. Body weight increased little as peripheral oedema and a raised jugular venous pressure appeared. The subsequent weight-loss during treatment was usually greater than the pre-treatment weight-gain. Body weight increased slowly in convalescence to equal or exceed hospital admission weight without a deterioration of general health or reappearance of oedema. 3. Total body water, exchangeable sodium and exchangeable potassium were measured in patients after treatment of the acute illness and clearance of oedema and again in six patients of the group 2-3 months later in convalescence. Total exchangeable sodium was normal or slightly reduced after treatment of oedema and in convalescence between recurrent acute illnesses. Even when gross oedema was present exchangeable sodium was substantially increased in only one of three patients studied at this stage. Total exchangeable potassium was invariably severely depressed. 4. Large changes of body tissue weight without comparable change in exchangeable sodium support previous evidence that oedema in hypoxic bronchitis is not simply a further form of congestive cardiac failure. 5. It is suggested that at least some of the tissue loss in acute exacerbations is a direct result of hypoxaemia and similar to that observed at high altitude. Part of the oedema fluid is thought to be derived from intracellular water released during dissolution of tissue matrix.

Aged↗
PubMed2002

Changes in lean body mass and total body weight are weakly associated with physical functioning in patients with HIV infection.

CONTEXT: For clinicians managing weight loss in patients with HIV, it would be useful to understand how changes in lean body mass (LBM) effect physical functioning, and whether LBM is more strongly related to physical functioning than total body weight (TBW). OBJECTIVE: To determine the relationship of changes in LBM and changes in total body weight (TBW) to changes in self-reported physical functioning in men and women with HIV infection. METHODS: Study design was longitudinal analysis of 1474 patient-intervals (each interval was approximately 6 months long) in 486 persons. Patients were participants in Nutrition for Healthy Living, a cohort study of HIV positive persons in Massachusetts and Rhode Island. The main outcome measure was change in self-reported physical functioning. RESULTS: Of the 1,474 intervals, 1,165 were contributed by men and 309 by women. The mean CD4 count for the 1,474 intervals was 383 cells/ micro L. In men, 5 kg changes in LBM and TBW were associated with 2.2 (95% confidence interval, 0.9, 3.4, P= 0.001) and 2.6 (95% confidence interval, 1.3, 3.9, P= 0.0002) point changes in physical functioning (on a 100-point scale), respectively, after adjusting for covariates. The relationships of changes in LBM and TBW to changes in physical functioning were linear. In women, there were no significant relationships between changes in LBM or TBW to changes in physical functioning. CONCLUSIONS: In this longitudinal analysis of relatively healthy persons with HIV infection, changes in LBM and TBW were significantly related to changes in physical functioning in men, but the magnitude of the relationship was small. In women, changes in LBM and TBW were not related to changes in physical functioning. Our data suggest that it is not necessary to measure body composition (lean and fat compartments) to understand the impact of changes in weight on physical functioning - it is sufficient to follow total body weight.

Adult↗
PubMed2001

Longitudinal changes in body mass index and body composition over 3 years and relationship to health outcomes in Hong Kong Chinese age 70 and older.

OBJECTIVES: To determine longitudinal changes in body mass index (BMI) and body composition with age and the relationship between these changes with mortality, morbidity, functional capacity, and other health outcome measures. DESIGN: A 3-year longitudinal study of a random sample of community-living subjects. SETTING: Older Chinese in the Hong Kong Special Administrative Region of China. PARTICIPANTS: Two thousand and thirty-two Chinese subjects age 70 and older recruited territory-wide by proportional random sampling. MEASUREMENTS: Baseline information collected included medical history, self-perceived health, Barthel Index, Geriatric Depression Score, time taken to complete a 16-foot walk, height, weight, mid-arm circumference, arm skin-fold thickness, and waist/hip ratio. Body composition was calculated from prediction equation. Outcome measures included mortality, development of new diseases, Barthel Index, time taken for 16-foot walk, self-perceived health, and Geriatric Depression Score. RESULTS: All parameters, with the exception of triceps skin-fold thickness in men, decreased, regardless of presence or absence of disease. The decrease in arm circumference, triceps skin-fold thickness, and total body fat (TBF) was greater in women than in men, whereas men had a greater decrease in fat-free mass (FFM). Even in the absence of disease, three times as many subjects lost > or =5kg in weight as gained > or =5kg (15% vs. 5%), and only age could be identified as a contributing factor to this weight loss. In the absence of disease, lower anthropometric indices were associated with greater mortality, development of new disease (in women only), dependency, and poor performance measure. Waist-hip ratio was not associated with mortality or any other health outcomes. Decrease in both FFM and TBF were associated with worse outcomes, the effect being more marked in women. CONCLUSION: In the older population, changes in weight and body composition occur even in the absence of disease and are associated with mortality and physical functioning level. Weight loss rather than weight gain appears to be more important in this population, and promotion of life-style interventions targeted at weight maintenance would be important.

Activities of Daily Living↗
PubMed2002

Measurement of total body water using 2H dilution: impact of different calculations for determining body fat.

This study estimated total body water (TBW) in four groups (twelve per group; sedentary and highly trained men and women) at the time of 2H dosing (T0) and after a 3.5 h equilibration period (Teq). Standard TBW calculations were employed at T0 (no correction for disproportionate urinary tracer loss) and Teq (correction for urinary tracer loss only), plus those calculations that corrected for a disproportionate urinary tracer loss and insensible tracer loss respectively. The measurement of body density enabled the four TBW estimates to be compared for the determination of three-compartment % body fat (BF). The very small difference between the standard and corrected T0 TBW data was not significant (P=0.914) and no GroupxTBW interaction was identified (P=0.125). These results reflect the closeness of the 2H concentration in the urine produced during the equilibration period and the Teq saliva samples. The associated mean % BF values were essentially identical. Although correcting for insensible 2H losses in addition to urinary losses at Teq produced a statistically significant (P<0.001) lower mean TBW (about 200 g) than the standard calculation, this translated to a small difference in % BF (0.3). The larger difference (about 500 g, P<0.001) between the two (T0, Teq) corrected TBW calculations was also associated with a small body composition difference (0.1 % BF), which was less than the propagated error (0.3 % BF) for the three-compartment body composition model. Corrections to the standard calculations of TBW at T0 and Teq for a protocol employing a brief equilibration period (3.5 h) were therefore of marginal use for improving the accuracy of % BF estimates. The TBW difference over time (T0 v. Teq) also had little impact on % BF values.

Adipose Tissue↗
PubMed1984

Age, body weight and body composition requirements for the onset of sexual maturity of dwarf and normal chickens.

Comparisons of age, food intake, body weight and body composition at the onset of sexual maturity were made between dwarf and normal chickens from lines selected for high or low juvenile body weight. At the same age birds which had started to lay were significantly heavier and contained significantly more abdominal and carcass fat than those which were not laying. Differences between normal and dwarf pullets within lines varied with genetic background, indicating differences between lines in meeting a body weight or a body composition requirement, or both, for the onset of sexual maturity.

Adipose Tissue↗
PubMed1992

Predicting total body water and extracellular fluid volumes from bioelectrical measurements of the human body.

Two biological impedance analyzers, a 50 kHz (RJL) and 20-100 kHz (BMA) instrument, and a total body electrical conductivity (TOBEC) instrument were used to estimate total body water (TBW), extracellular (ECF) and intracellular (ICF) fluid volumes by repeated measurements of 16 normal men (19-38 years old) to assess which, if any, would provide the best estimates. At 3-week intervals, TBW was determined by deuterium dilution, ECF by bromide dilution, ICF by difference (TBW-ECF) and lean body mass by density. Prediction equations were obtained by regression; predicted values for the body fluid volumes were calculated and the results were statistically evaluated. Both the TOBEC and the BMA provided rapid and reliable estimates for body fluid volumes with standard errors of the estimates of about 0.5-1.1 L for ECF, 1.0-1.8 L for TBW, and 1.0-1.3 L for ICF. Part of the error was attributable to standard tracer-dilution methods.

Adult↗
PubMed1980

A longitudinal study of body weight and body fat changes in Antarctica.

Body weight and body fat changes (calculated from skinfold thickness) that occurred in a male population spending a year on an Antarctic base are described. There was a marked individual variation in patterns of weight and fat changes between seasons but mean values for the whole community showed little change over the year. Combining skinfold and body weight measurements revealed probable individual differences in fat gain or loss with weight gain and loss, but the role of changes in total body water or fat-free mass could not be determined. The possibility of combining long-term measurements of body fat and energy intake to provide an estimate of energy expenditure is discussed.

Adipose Tissue↗
PubMed1989

Total-body electrical conductivity (TOBEC): relationship to estimates of muscle mass, fat-free weight, and lean body mass.

A comparison of methods for estimating body composition (BC) of 12 subjects was made by using fat-free weight from total-body electrical conductivity (FFWT), muscle mass from 3-methylhistidine excretion (MM3MH) and creatinine excretion (MMCRE), fat-free weight from hydrostatic weighing (FFWBD), and lean body mass from whole-body potassium counting (LBMK). Data were analyzed for day-to-day variability and regression analyses were applied to compare the different methods of measuring BC. Mean values (+/- SEM, kg) for the estimates were 53.9 +/- 3.5 (FFWT), 26.9 +/- 2.9 (MM3MH), 25.3 +/- 2.5 (MMCRE), 53.2 +/- 3.6 (FFWBD), and 52.8 +/- 3.5 (LBMK). Regression analyses revealed that TOBEC estimates of fat-free weight had an adjusted r2 (+/- SEE, kg) of 0.95 +/- 2.2, 0.50 +/- 7.9, 0.95 +/- 1.8, and 0.88 +/- 4.0 for MM3MH, MMCRE, FFWBD, and LBMK, respectively. It was concluded that TOBEC is a potentially reliable method for estimating the muscle mass within the fat-free compartment, as well as fat-free weight and lean body mass.

Adipose Tissue↗
PubMed1993

Adipose tissue distribution as assessed by magnetic resonance imaging and total body fat by magnetic resonance imaging, underwater weighing, and body-water dilution in healthy women.

A method for estimating total body fat (TBF) and the amount and distribution of adipose tissue in humans by using magnetic resonance imaging (MRI) is described. Thirty transaxial images of subjects were taken by a nuclear magnetic imager (0.02 T). Adipose tissue volume was calculated from adipose tissue area in each image and from the distances between images. The CV when estimating total volume of body adipose tissue was 1.5%. TBF of healthy Swedish women was estimated by the MRI method (n = 25), by underwater weighing (UWW) (n = 20), and by body-water dilution (BWD) (n = 23). When assessed by MRI and BWD, women contained 1.4 +/- 2.9% less and 4.7 +/- 4.0% more TBF, respectively, than when assessed by UWW. On average, 74.2% of total adipose tissue volume was situated subcutaneously. Subcutaneous fat:fat-free body weight and nonsubcutaneous fat:fat-free body weight were both significantly correlated with percent TBF but the women stored excess fat subcutaneously rather than nonsubcutaneously.

Adipose Tissue↗
PubMed1999

Validity of the body mass index as an indicator of the risk and presence of overweight in adolescents.

The validity of the body mass index (BMI) as an indicator of the risk of becoming overweight and of the presence of overweight was evaluated in 6 groups of adolescents comprising several ethnic groups (n = 1570, aged 9-19 y). With use of triceps skinfold thickness and estimated percentage body fat as the criteria for adiposity, BMI had high specificities (86.1-98.8% for risk of overweight and 96.3-100% for presence of overweight) and lower but variable sensitivities (4.3-75.0% for risk of overweight and 14.3-60% for presence of overweight). Thus, almost all adolescents who were not at risk for overweight or who were not overweight were classified correctly. In contrast, many adolescents who were at risk of overweight or who were overweight were not correctly identified as measured by BMI. Partial correlations, controlling for age, between BMI and the triceps skinfold thickness and estimated percentage body fat were generally moderate to moderately high, whereas BMI and triceps skinfold thickness appeared to be equally related to estimated total body fatness and percentage body fat in Mexican American and Austrian white males. BMI was better correlated with trunk skinfold thicknesses, but when relative subcutaneous fat distribu-tion was statistically controlled, the trunk-extremity contrast in the correlations was no longer apparent.

Journal Article↗
PubMed1990

Failure to demonstrate an effect of dietary fatty acid composition on body weight, body composition and parameters of lipid metabolism in mature rats.

The objectives of the present study were to examine the effects of dietary fatty acid composition on body composition and on several parameters of lipid metabolism in adipose tissue and to assess the ease of weight loss with restricted dietary intake. Rats were fed diets containing 14% fish oil, safflower oil or beef fat plus 2% corn oil. These diets were fed ad libitum for 4 wk (first phase). A number of the animals from each group were killed, and the others were fed 50% of their first-phase food intake for an additional 4 wk (second phase). The diets used in the second phase contained 3% of the above fats plus 2% corn oil. Food consumption, food efficiency and body weights were monitored. After the rats were killed, fatty acid composition of epididymal fat pads was examined. In addition, in vivo lipolysis and in vitro lipogenesis in epididymal fat pads were examined. The results indicate that dietary fatty acid composition had no effect on body weight, food consumption, in vivo lipolysis and in vitro lipogenesis in epididymal fat pads. In addition, although dietary fatty acid manipulation resulted in alteration in adipose tissue fatty acid composition, it had no effect on the rate of weight loss, body composition, in vivo lipolysis and in vitro lipogenesis in epididymal fat pads. It is concluded that dietary fatty acid composition does not play a role in body composition and in lipid metabolism in adipose tissue of mature rats.

Animals↗
PubMed1996

Sex differences in measures of body fat and body fat distribution in the elderly.

This study describes sex differences in obesity and body fat distribution using commonly used assessment methods in 140 men and 245 women age 65-96 years from Rancho Bernardo, California. Significant correlations were shown among all obesity measures. The waist/hip ratio was more strongly correlated with the truncal fat/leg fat ratio in women than in men. The waist/hip ratio correlated significantly with the subscapular/ triceps skinfold ration in women only. In both sexes, waist circumference was more strongly correlated with body mass index and the percentage of body fat by bioelectric impedance analysis and dual-energy X-ray absorptiometry than with the waist/hip ratio. In those aged over 80 years, age stratification showed that the waist/hip ration was not correlated with any other measurement of obesity or fat distribution in men and correlated only with subscapular skinfolds in women. Waist circumference, however, correlated significantly with almost all other measures of central obesity in older and younger men and women. Estimates of upper body (central) fat distribution appear to be age specific. After age 80, the waist/hip ratio is a poor method of assessing central or visceral adiposity, and waist circumference is a better measure of body fat distribution.

Absorptiometry, Photon↗
PubMed2004

The neural correlates of perceiving human bodies: an ERP study on the body-inversion effect.

The present study investigated the neural correlates of perceiving human bodies. Focussing on the N170 as an index of structural encoding, we recorded event-related potentials (ERPs) to images of bodies and faces (either neutral or expressing fear) and objects, while subjects viewed the stimuli presented either upright or inverted. The N170 was enhanced and delayed to inverted bodies and faces, but not to objects. The emotional content of faces affected the left N170, the occipito-parietal P2, and the fronto-central N2, whereas body expressions affected the frontal vertex positive potential (VPP) and a sustained fronto-central negativity (300-500 ms). Our results indicate that, like faces, bodies are processed configurally, and that within each category qualitative differences are observed for emotional as opposed to neutral images.

Adolescent↗
PubMed1994

Relationship between body weight, body surface area and serum zidovudine pharmacokinetic parameters in adult, male HIV-infected patients.

OBJECTIVE: To determine whether there is a simple relationship between body weight or body surface area (BSA) and serum zidovudine pharmacokinetic parameters in patients receiving oral zidovudine. DESIGN: Single-dose, pharmacokinetic study. PATIENTS: Fifty-three asymptomatic and symptomatic HIV-infected men (CD4+ cell count < 500 x 10(6)/l) participated in the study. Results of renal function and haematology tests were within normal limits and all hepatic function tests were up to three times the upper limit of normal. Patients received 200 mg oral zidovudine and serial blood samples were collected for 4 h (18 patients) or 8 h (35 patients). Serum zidovudine concentrations were measured by high-performance liquid chromatography (12 patients) or radioimmunoassay (41 patients). Pharmacokinetic parameters were calculated by non-compartmental methods. The relationships between body weight or BSA and maximum serum concentration (Cmax), area under the concentration-time curve (AUC), apparent serum clearance (CL/F), and apparent terminal volume of distribution (Vz/F) were determined by simple least-squares linear regression. RESULTS: There were no significant relationships between either body weight or BSA and Cmax, AUC, Vz/F (corrected for weight), and clearance (P > 0.07; R2 < 0.06 for all comparisons). A significant positive association between Vz/F, uncorrected for weight, and either weight (P = 0.011; R2 = 0.121) or BSA (P = 0.022; R2 = 0.098) was observed. The interindividual coefficients of variation of CL/F and Vz/F values were only marginally reduced when the parameters were corrected for weight (31.3 versus 30.8% and 28.0 versus 26.0% respectively). CONCLUSIONS: There is little or no linear association between either body weight or BSA and observed serum zidovudine concentrations following administration of 200 mg zidovudine in adult male patients who are within 20% of their ideal weight.

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↗
PubMedDate not supplied

Body composition, body size estimation, and attitudes towards eating in male college athletes.

A number of different parameters relating to eating history and body composition were examined in male college athletes during the course of an athletic season. Wrestlers, who often lose weight to meet the requirements of the sport, were compared with other athletes (swimmers, nordic skiers) who typically maintain weight during vigorous training. By the end of the athletic season, the wrestlers had reduced body weights and reported a reduction in caloric intakes. Wrestlers scored higher than swimmers and nordic skiers on scales measuring dietary restraint and attitudes towards eating (EAT). The groups differed primarily on items dealing with fluctuations in body weight and with dieting behaviors. There were no significant differences between groups on the estimates of body size and no effect of seasonal training. However, a small subsample of the wrestlers who scored high on the restraint and EAT scales also showed distortions in estimates of body size. Wrestlers may represent a population at risk for the newly reported sports-induced disturbances in eating.

Adolescent↗
PubMedDate not supplied

Men and body image: are males satisfied with their body weight?

Dissatisfaction with body image is thought to be a key factor in the etiology of eating disorders among women. In contrast, men are reported to be generally satisfied with their body weight and body shape. The present survey study examined the relative desire for thinness or weight gain among 226 male and female freshman students. Most 18-year-old women (85%) wished to lose weight. Men expressed conflicting views regarding desire for thinness and were almost evenly split between those who wanted to lose weight (40%) and those who wished to gain weight (45%). The proportion of men and women who expressed no desire for weight change was comparable. Men and women who wished to lose weight shared negative body perceptions: both groups viewed themselves as overweight, and both expressed dissatisfaction with body shape. However, men used exercise for weight control while women resorted to restricted calorie diets. A key risk factor for eating disorders may be dieting itself.

Adolescent↗