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PubMed1983

Measurement of total body electrical conductivity: a new method for estimation of body composition.

A new method for the estimation of body composition in human subjects is described which entails the measurement of total body electrical conductivity. The method is based on the principle that the electrical conductivity of lean tissue is far greater than that of fat. Comparative studies in 19 adults of widely varying fatness have demonstrated excellent correlations between the total electrical conductivity of the subjects and both their total body water (r = 0.87) and total body potassium (r = 0.86). This noninvasive method, which is safe, simple, rapid, and convenient, should prove useful in the nutritional assessment of individuals and populations.

Adult↗
PubMed1996

Prediction of body cell mass, fat-free mass, and total body water with bioelectrical impedance analysis: effects of race, sex, and disease.

The inability to precisely estimate body composition with simple, inexpensive, and easily applied techniques is an impediment to clinical investigations in nutrition. In this study, predictive equations for body cell mass (BCM), fat-free mass (FFM), and total body water (TBW) were derived from direct measurements through use of single-frequency bioelectrical impedance analysis (BIA) in 332 subjects, including white, black, and Hispanic men and women, who were both healthy control subjects and patients infected with the human immunodeficiency virus (HIV). Preliminary studies showed more accurate predictions of BCM when parallel-transformed values of reactance were used rather than the values reported by the bioelectrical impedance analyzer. Modeling equations derived after logarithmic transformation of height, reactance, and impedance were more accurate predictors than equations using height2/resistance, and the use of sex-specific equations further improved accuracy. The effect of adding weight to the modeling equation was less important than the BIA measurements. The resulting equations were validated internally, and race and disease (HIV infection) were shown not to affect the predictions. The equation for FFM was validated externally against results derived from hydrodensitometry in 440 healthy individuals; the SEE was < 5%. These results indicate that body composition can be estimated with simple and easily applied techniques, and that the estimates are sufficiently precise for use in clinical investigation and practice.

Adult↗
PubMed1997

Changes in total body fat during the human reproductive cycle as assessed by magnetic resonance imaging, body water dilution, and skinfold thickness: a comparison of methods.

Total body fat and fat-free mass were assessed by magnetic resonance imaging (TBFMRI and FFMMRI) in 11-16 healthy Swedish women before pregnancy and 5-10 d and 2, 6, and 12 mo after delivery. On these occasions, TBF was also measured by the body water dilution (TBFBWD) and skinfold-thickness (TBFSFT) techniques. The results were used to compare changes in TBFSFT and TBFBWD during reproduction with changes in TBFMRI. TBFBWD was 1.5-4.0 kg higher than TBFMRI and at all postpartum measurements the difference between these estimates increased significantly with increased body fat content. This difference was also significantly higher 6 mo after delivery than it was 2 and 12 mo postpartum. The possibility that this was due to variations in the degree of hydration of FFM postpartum was considered. TBFSFT was 1.7-3.1 kg higher than TBFMRI and this difference increased with increasing body fat content. The agreement between changes in TBFMRI and TBFSFT was different during different times in the reproductive cycle and was also influenced by the amount of fat lost or gained. The findings thus suggest that there is a risk for bias when changes in TBF during reproduction are estimated by the skinfold-thickness technique as well as by isotope dilution.

Adipose Tissue↗
PubMed2002

Longitudinal changes in body composition in older men and women: role of body weight change and physical activity.

BACKGROUND: Estimates of body-composition change in older adults are mostly derived from cross-sectional data. OBJECTIVE: We examined the natural longitudinal patterns of change in fat-free mass (FFM) and fat mass (FM) in older adults and explored the effect of physical activity, weight change, and age on these changes. DESIGN: The body composition measured by hydrodensitometry and the level of sports and recreational activity (SRA) of 53 men and 78 women with a mean (+/-SD) initial age of 60.7 +/- 7.8 y were examined on 2 occasions separated by a mean (+/-SD) time of 9.4 +/- 1.4 y. RESULTS: FFM decreased in men (2.0% per decade) but not in women, whereas FM increased similarly in both sexes (7.5% per decade). Levels of SRA decreased more in men than in women over the follow-up period. Baseline age and level of SRA were inversely and independently associated with changes in FM in women only. Neither age nor level of SRA was associated with changes in FFM in men or women. Weight-stable subjects lost FFM. FFM accounted for 19% of body weight in those who gained weight, even in the presence of decreased levels of SRA. Loss of FFM (33% of body weight) was pronounced in those who lost weight, despite median SRA levels >4184 kJ/wk. CONCLUSIONS: On average, FM increased; however, the increase in women was attenuated with advancing age. The decrease in FFM over the follow-up period was small and masked the wide interindividual variation that was dependent on the magnitude of weight change. The contribution of weight stability, modest weight gains, or lifestyle changes that include regular resistance exercise in attenuating lean-tissue loss with age should be explored.

Adipose Tissue↗
PubMed2002

Betaine supplementation decreases plasma homocysteine concentrations but does not affect body weight, body composition, or resting energy expenditure in human subjects.

BACKGROUND: Betaine (trimethylglycine) is found in several tissues in humans. It is involved in homocysteine metabolism as an alternative methyl donor and is used in the treatment of homocystinuria in humans. In pigs, betaine decreases the amount of adipose tissue. OBJECTIVE: The aim of the study was to examine the effect of betaine supplementation on body weight, body composition, plasma homocysteine concentrations, blood pressure, and serum total and lipoprotein lipids. DESIGN: Forty-two obese, white subjects (14 men, 28 women) treated with a hypoenergetic diet were randomly assigned to a betaine-supplemented group (6 g/d) or a control group given placebo for 12 wk. The intervention period was preceded by a 4-wk run-in period with a euenergetic diet. RESULTS: Body weight, resting energy expenditure, and fat mass decreased significantly in both groups with no significant difference between the groups. Plasma homocysteine concentrations decreased in the betaine group ( +/- SD: 8.76 +/- 1.63 micro mol/L at 4 wk, 7.93 +/- 1.52 micro mol/L at 16 wk; P = 0.030 for the interaction of time and treatment). Diastolic blood pressure decreased without a significant difference between the groups. Serum total and LDL-cholesterol concentrations were higher in the betaine group than in the control group (P < 0.05). CONCLUSION: A hypoenergetic diet with betaine supplementation (6 g daily for 12 wk) decreased the plasma homocysteine concentration but did not affect body composition more than a hypoenergetic diet without betaine supplementation did.

Adult↗
PubMed1999

Core body temperature and sleep of older female insomniacs before and after passive body heating.

The purpose of this study was to investigate the relationship between core body temperature and sleep in older female insomniacs and changes in that relationship as a result of passive body heating (PBH). An increase in body temperature early in the evening by way of PBH in older female insomniacs increased SWS in the early part of the sleep period and improved sleep continuity. Fourteen older female insomniacs (60-73 years old) participated in at least two consecutive nights of PBH involving hot (40-40.5 degrees C) baths 1.5-2 hours before bedtime. Hot baths resulted in a significant delay in the phase of the core body temperature rhythm compared to baseline nights. This delay in temperature phase paralleled the improvements in sleep quality.

Adult↗
PubMed1980

Compartmental body composition based on total-body nitrogen, potassium, and calcium.

The techniques of prompt gamma neutron-activation analysis for the measurement of total-body nitrogen and whole-body counting for the measurement of total-body potassium were used to determine the mass of muscle and nonmuscle lean tissue and their protein content in 135 normal male and female subjects, 20-80 yr of age. Age-related changes in the size of the muscle and nonmuscle compartments and their protein content provide basic data for the investigation of protein metabolism in aging subjects and in individuals with various metabolic disorders, particularly wasting diseases such as cancer. Significant age-related changes in the size of various body compartments were noted. The loss of muscle mass and its protein content contrasts with the relative constancy of the nonmuscle lean tissue and suggests that skeletal muscle is particularly vulnerable to the aging process.

Adult↗
PubMed1987

Total body electrical conductivity measurements: effects of body composition and geometry.

This study used an animal model to analyze the effect of body geometry and chemical composition on the calibration of a total body electrical conductivity (TOBEC) instrument developed to measure the body composition of human infants. The TOBEC signal (adjusted for length) of infant miniature pigs from 10 to 33 days of age correlated highly with their chemically analyzed fat-free mass (FFM; r = 0.998) and total body water contents (TBW; r = 0.998); 95% prediction intervals (approximately +/- 2 SEE) for individual measurements were +/- 0.16 kg FFM and +/- 0.12 liter water. These values were significantly improved (+/- 0.08 kg and +/- 0.06 liter, respectively) by accounting for individual variability in weight/length2. The effect of variations in the composition of FFM on the TOBEC measurements was evaluated by comparing the response of the infant piglets with that of adult rabbits of similar size. The differences in composition, primarily TBW and Na content, were insufficient to alter the electrical properties of FFM appreciably. Thus the TOBEC used under the conditions defined in this study accurately predicted the FFM and TBW content of infant miniature pigs. The calibration derived from the piglets will be applicable to the interpretation of the TOBEC measurements of human infants provided their FFM is of comparable shape to that of the piglets. Differences in composition are likely to be of consequence only if the proportion of fat within the FFM and the FFM density are widely divergent. This, however, does not appear to be the case.

Animals↗
PubMed1998

Effect of repeated stress on body weight and body composition of rats fed low- and high-fat diets.

Exposure to the moderate stressor of 3-h restraint for 3 consecutive days causes a temporary drop in food intake but a permanent reduction in body weight in adult rats. Young rats did not show the same response. Food intake of adult rats exposed to repeated restraint was significantly lower than that of controls for 4 days after the end of stress, and there was no rebound hyperphagia. Body weight remained significantly lower for at least 40 days after stress. When the rats were fed a high-fat diet of 80% chow and 20% vegetable shortening (48% kcal fat, 16% protein), lean body mass accounted for all of the weight loss in stressed rats. When the experiment was repeated with a purified high-fat diet containing corn oil and coconut oil as the source of fat (41% kcal fat, 16% protein), weight loss consisted of both lean and fat tissue. There were no sustained changes in single time point measures of corticosterone, insulin, or leptin that could account for the reduced body weight in these rats.

Aging↗
PubMed1976

Effects of lower body negative pressure (LBNP) on the distribution of body fluids.

Reduction of pressure on the lower part of the human body is believed to be capable of altering the normal fluid distribution. This could serve as a therapeutic method for emergency relief of the effects of hypertension, or it could be used as counterbalance for zero gravity and assist in preparing astronauts for reentry into the gravitational field. The present work describes a technique of assessment of the fluid shift caused by such pressure reduction. Thirty experiments were performed on four healthy subjects. The shift of fluid was assessed by measuring changes in body weight distribution of the tested subjects. The shift of fluid was assessed by measuring changes in body weight distribution of the tested subjects. The experimental results show that two processes may have taken place within the human body: shift of blood within the vascular system and diffusion of fluids from the circulatory system to the tissues. The total fluid shift ranges between 1 and 2 kg. It was proportional to the pressure gradient and exponential with time. The systolic blood pressure was reduced with the pressure reduction while the pulse rate increased.

Body Fluids↗
PubMed1980

Relative responses of aortic body and carotid body chemoreceptors to hypotension.

Responses to acute arterial blood pressure changes of a single or a few chemoreceptor afferents from the aortic body and carotid body at constant arterial blood gases and pH were measured in 16 adult cats. During normocapnic normoxia and moderate hypoxia (arterial oxygen tension of 60 Torr) an induced hypotension of 80 Torr increased strikingly the discharge rate of all aortic chemoreceptors but not of most carotid chemoreceptors; hypotension down to the level of 50 Torr stimulated most carotid chemoreceptors only slightly. Hyperoxia eliminated the stimulatory effect of this degree of hypotension on carotid chemoreceptors; it did not affect aortic chemoreceptors to the same extent. Hypoxia augmented the effect on aortic chemoreceptors more than the effect on carotid chemoreceptors. Thus the effect of hypotension was dependent on arterial oxygen tension. The greater effect of hypotension on aortic body chemoreceptor activity indicates a greater normal circulatory constraint for the aortic body. Accordingly, aortic chemoreceptors are more suited to monitor circulatory changes in O2 flow, and carotid chemoreceptors are more suited to monitor arterial gas pressure changes due to respiration.

Animals↗
PubMed1981

Relative responses of aortic body and carotid body chemoreceptors to carboxyhemoglobinemia.

The effects of carbon monoxide inhalation and of consequent carboxyhemoglobinemia (HbCO) on the discharge rates of aortic body and carotid body chemoreceptor afferents were investigated in 18 anesthetized cats. In 10 experiments both aortic and carotid chemoreceptor activities were monitored simultaneously. Carbon monoxide inhalation during normoxia always stimulated aortic chemoreceptors before carotid chemoreceptors, and the steady-state response of aortic chemoreceptors to HbCO was greater than that of most carotid chemoreceptors. Only 2 of the 18 carotid chemoreceptor fibers tested showed a distinct increase in activity in response to moderate increases in HbCO%. Thus, oxyhemoglobin contributed substantially to maintain tissue PO2 of all aortic chemoreceptors and of a few carotid chemoreceptors. Hyperoxia diminished the response of both aortic and carotid chemoreceptors to HbCO, indicating a lowered tissue PO2 as the stimulus source. We hypothesize that the aortic bodies have a much lower perfusion relative to their O2 utilization compared to the carotid bodies. As a consequence, the aortic chemoreceptors are able to act as a sensitive monitor of O2 delivery and to generate a circulatory chemoreflex for O2 homeostasis. carotid chemoreceptors monitor O2 tension and initiate strong reflex effects on the level of ventilation.

Animals↗
PubMed1999

Modeling the influence of body size on V(O2) peak: effects of model choice and body composition.

This study examined the bivariate relationship between peak oxygen uptake (V(O2) peak); l/min) and body size in adult men (n = 1,314, age 17-66 yr), using both "simple" and "full" iterative nonlinear allometric models. The simple model was described by V(O2) peak = M(b) (or FFM(b)) exp(c SR-PA) exp(a + d age) epsilon (where M is body mass in kg; FFM is fat-free mass in kg; SR-PA is self-reported physical activity; epsilon is a multiplicative error term; and exp indicates natural antilogarithms). The full model was described by V(O2) peak = M(b) (or FFM(b)) exp(c SR-PA) exp(a + d age) + e (epsilon), where e is a permitted Y-intercept term. The M exponent obtained from simple allometry was 0.65 [95% confidence interval (CI), 0.59-0.71], suggestive of a curvilinear relationship constrained to pass through the origin. This "zero Y-intercept" assumption was examined via the full allometric model, which revealed an M exponent of 1.00 (95% CI, 0.7-1.31), together with a positive Y-intercept term (e) of 1.13 (95% CI, 0.54-1.73). The FFM exponents were not significantly different from unity in either the simple or full allometric models. It appears that the curvilinearity of the simple allometric model (using total M) is fictitious and is due to the inappropriate forcing of the regression line through the origin. Utilizing FFM as the body-size variable revealed a linear relationship between body size and V(O2) peak, irrespective of model choice. We conclude that the population mass exponent for V(O2) peak is close to unity.

Adolescent↗
PubMedDate not supplied

Gallbladder volume in adults and its relationship to age, sex, body mass index, body surface area and gallstones. An epidemiologic study in a nonselected population in France.

BACKGROUND/AIMS: The role of a large gallbladder volume with regard to a predisposition for gallstones is unknown. It is possible that an increase in gallbladder volume could result in impaired gallbladder motility and bile stasis. We looked for factors affecting gallbladder volume in a random population in the southeast of France. METHODS: To assess the relationship between gallbladder volume and gallstones, 528 subjects over the age of 30 were studied (72 with lithiasis). Age, sex, body mass index, body surface area and gallbladder volume were collected for each subject. A linear regression analysis was performed to look for significant variables. RESULTS: The overall adjusted prevalence of cholelithiasis was 13.9% in our population. On linear regression analysis, two variables (age and surface area) were found to be independently correlated with gallbladder volume. Gallbladder volume was significantly increased in subjects over 50 years (p < 0.001). There was a positive correlation between gallbladder volume and body surface area (r = 0. 33, p < 0.001). In this study, the presence or absence of gallstones did not significantly affect the gallbladder volume. CONCLUSIONS: We report that there is dilatation of the gallbladder with age and with an increase in body surface area. Whether this could represent risk factors for the occurrence of gallstone remains uncertain.

Adult↗
PubMed1985

Body composition in elderly people. I. Determination of body composition by multiisotope method and the elimination kinetics of these isotopes in healthy elderly subjects.

The body composition of 40 healthy elderly and 20 healthy young subjects was determined and compared. It was found that the age-related changes were more marked in females than in males. Total body water was decreased as a consequence of diminished lean body mass. Extracellular fluid volume remained unchanged, while plasma volume increased. Thus, the liquid components of lean body mass were redistributed between the intracellular and extracellular spaces. The elimination kinetics of isotopes were not significantly different between young and aged subjects, except the elimination of radiosulfate.

Aged↗
PubMed1998

Body weight, body composition, and energy intake changes in breastfeeding mothers.

Body weight, body composition, and energy intake changes are described for 13 breastfeeding mothers followed for 18-24 months after delivery. Body weight was assessed at 1-6, 9, 12, 18, 24 months postpartum and 1 month after infant weaning, and energy intake was assessed at 2-6, 9, 12, 18, 24 months postpartum and 1 month after infant weaning. Compared to prepregnancy weight, participants were an average of 4.0 +/- 6.6 kg heavier 18 months postpartum (p < 0.05). The mean rate of weight loss from 1 month postpartum until termination of lactation was 0.32 +/- 0.27 kg/month. Eight of the 12 women gained weight after weaning their infant. Percent body fat assessed by underwater weighing declined from 34.6 +/- 2.8% at 1 month postpartum to 31.4 +/- 4.8% at 1 month after infant weaning (p < 0.05). Further research is needed to study the factors which affect weight loss postpartum, and how weight gain after weaning can be prevented.

Adult↗
PubMed2001

A prevalent polymorphism in the promoter of the UCP3 gene and its relationship to body mass index and long term body weight change in the Danish population.

Variability of the uncoupling protein 3 (UCP3) promoter has been associated with increased body mass index (BMI) and altered lipid profiles. Here we tested the hypothesis that variation of the UCP3 promoter is associated with either juvenile or maturity-onset obesity or body weight change over a 26-yr follow-up among Danish subjects. Mutation screening of approximately 1 kb 5' upstream of the UCP3 gene revealed one previously described -55 C-->T variant. The frequency of the polymorphism was evaluated by restriction fragment length polymorphism analysis in four groups of subjects: 1) a group of 744 obese Danish men who at the draft board examinations had a body mass index (BMI) of at least 31 kg/m(2), 2) a randomly selected control group consisting of 857 draftees, 3) 258 middle-aged subjects, and 4) 409 60-yr-old subjects. The frequency of the T allele was 26.0% (95% confidence interval, 23.8-28.2%) among the obese draftees and 26.9% (24.8-29.0%) in the control group (P = 0.6). The variant was not associated with BMI at a young age or with weight gain after a 26-yr follow-up. The frequency of the T allele was 29.5% (25.6-33.4%) in the middle-aged group and 25.8% (22.8-28.8%) among the 60-yr-old subjects. The polymorphism was not associated with increased BMI or percent body fat in these 2 groups. It is concluded that this variant does not play a major role in the development of common obesity among Danish subjects.

Adult↗
PubMed2004

Effects of whole-body exercise training on body composition and functional capacity in normal-weight patients with COPD.

BACKGROUND: Skeletal muscle wasting is related to muscle dysfunction, exercise intolerance, and increased mortality risk in patients with COPD. STUDY OBJECTIVES: The aims of this study were to investigate the effects of whole-body exercise training on body composition in normal-weight patients with COPD, and to study the relationship between changes in body composition and functional capacity. SETTING AND PARTICIPANTS: Fifty patients with COPD (FEV(1), 39% of predicted [SD, 16]) admitted to the pulmonary rehabilitation center at Hornerheide, and 36 healthy age-matched control subjects (for baseline comparison) were included. INTERVENTIONS: Patients participated in a standardized inpatient exercise training program consisting of daily submaximal cycle ergometry, treadmill walking, weight training, and gymnastics during 8 weeks. MEASUREMENTS: Fat-free mass (FFM) was measured by bioelectrical impedance analysis. None of the patients met the criteria for nutritional supplementation (body mass index </= 21, or FFM index </= 15 kg/m(2) in women and </= 16 kg/m(2) in men). Exercise capacity was measured using incremental cycle ergometry. Isokinetic quadriceps strength was measured with a Biodex dynamometer (Biodex Medical Corporation; Shirley, NY). RESULTS: At baseline, patients were characterized by a significantly lower FFM than the control subjects. Age and FFM were independent predictors of skeletal muscle function and exercise capacity in patients. After rehabilitation, weight (72.4 +/- 9.8 to 73.0 +/- 9.4 kg, p < 0.05) significantly increased, as a result of increased FFM (52.4 +/- 7.3 to 53.4 +/- 7.7 kg, p < 0.05), while fat mass (20.0 +/- 6.1 to 19.6 +/- 5.7 kg) tended to decrease. Peak work rate (63 +/- 29 to 84 +/- 42 W, p < 0.001), maximal oxygen consumption (O(2)max) [1,028 +/- 307 to 1,229 +/- 421 mL/min, p < 0.001], and isokinetic quadriceps strength (82.5 +/- 36.4 to 90.3 +/- 34.9 Newton-meters, p < 0.05) all improved. Changes in FFM were proportionally smaller than functional improvements, and were related to changes in O(2)max (r = 0.361, p < 0.05), but not to other changes in functional capacity. CONCLUSIONS: Intensive exercise training per se is able to induce an anabolic response in normal-weight patients with COPD classified into Global Initiative for Chronic Obstructive Lung Disease stages III-IV. Improvements in exercise performance and muscle function are proportionally larger than increases in FFM.

Aged↗