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PubMed1988

Changes in body composition in adolescent boys.

Changes in body composition were studied at age 10 and 13 years in 47 healthy school children of the Glasgow area. When seen at age 13, 22 had reached a total puberty rating (TPR) greater than 4 while the other 25 had a TPR less than 4. On relating body composition at age 10 with that observed at age 13 for the earlier maturing and later maturing boys it is clear that during this age period there are very fast and dynamic changes in body composition that can be characterized as a 'fat-wave' where children gain weight on a tissue that is almost 40 per cent fat, followed by the 'growth spurt' where they gain tissue that is almost 100 per cent lean mass while using up some of their body fat. Knowledge of this event is of importance for interpreting nutrition and body composition data in this age group especially when inter-social or inter-ethnic comparisons are being made. Some case observations suggest that the magnitude and direction of these changes in body composition can be influenced by environmental modulators, especially diet and physical activity.

Adolescent↗
PubMed1987

Body composition changes in marrow transplant recipients receiving total parenteral nutrition.

Nine patients with acute lymphocytic leukemia in remission, aged 12-35 years, undergoing allogeneic bone marrow transplantation (BMT) were studied for changes in body fluid balance and body composition. Body composition and fluids were assessed the first 4 weeks following BMT, using isotope dilution and anthropometry. Oral and parenteral nutrient intakes were recorded daily. Tracer dilution techniques were used to assess body fluid volumes and estimate body cell, lean body, and body fat masses. Body cell mass was lost (mean -1.62 kg, P less than 0.05) without significant changes in body fat or lean body masses. There was an expansion of the extracellular fluid compartment (mean +0.8 l, P less than 0.05) and a loss in the intracellular fluid compartment (mean -1.3 l, P less than 0.05) with little change in total body water volume. Changes in body weight correlated poorly with body cell mass or fluid volume changes. Change in arm muscle area correlated well with changes in body cell mass (r = 0.61, P less than 0.05) and lean body mass (r = 0.68, P less than 0.05), while that of arm fat area did not reflect its isotope dilution-derived counterpart. Instead, the change in arm fat area was related to shifts in fluid compartments. Prealbumin decreased significantly (mean -9.3 mg/dl, P less than 0.05), while albumin decreased slightly (mean -0.1 mg/dl), and both were related to changes in body cell mass. Nitrogen balance was negative throughout the study and the overall mean was related to the change in body cell mass (r = 0.60, P less than 0.05). Calorie and protein intakes were not associated with the changes in body composition, implying other causal factors.

Adolescent↗
PubMed1988

Malnutrition, nutritional support and total body composition.

The nutritional status and total body composition of 33 patients with malnutrition after biliopancreatic bypass were studied. Body composition was evaluated directly by measurement of water and total sodium and indirectly by measurement of total body potassium. After nutrition with a parenteral nutritional support the conventional nutritional parameters were restored to the normal values (serum albumin and serum transferrin) and the parameters of body composition were markedly improved even though still altered with respect to healthy controls. Serum albumin and serum transferrin were shown to be very reliable indices of malnutrition but their normalization does not necessarily correspond to optimum body composition and thus to optimal normal nutrition.

Amino Acids↗
PubMed1995

Estimating body composition in late gestation: a new hydration constant for body density and total body water.

Twenty women underwent body density (DB) measurements using underwater weighing with correction of residual lung volume by nitrogen dilution and total body water (TBW) using isotope dilution of 18O to estimate body composition at 30 wk of gestation. DB and TBW were used as independent variables in the same equation. The hydration constant (HC) of fat-free mass (FFM) was estimated as 0.762; based on this HC, new body composition equations for both DB and TBW were derived. These equations were prospectively tested in an additional 20 women at 30 wk of gestation. No significant differences were detected between estimates of percent body fat (%F) using either the newly derived DB or TBW equations and estimates of %F using both DB and TBW. Ten of these forty women were evaluated postpartum. There was no significant difference in %F estimated by either TBW or DB compared with standard equations (hydration of FFM = 0.72) and %F using both DB and TBW. These results highlight the importance of either measuring both DB and TBW or using an appropriate hydration constant for FFM in estimating body composition during pregnancy or conditions associated with increased body water.

Adult↗
PubMed2006

Metabolic consequences of body size and body composition in hemodialysis patients.

Small body mass index is associated with increased mortality in chronic hemodialysis patients. The reasons for this observation are unclear but may be related to body composition. This study aimed to investigate the body composition in chronic hemodialysis patients. The difference between body mass and the sum of muscle, bone, subcutaneous, and visceral adipose tissue masses, measured by whole body magnetic resonance imaging, was defined as the high metabolic rate compartment representing the visceral mass. Protein catabolic rate was calculated from urea kinetics. Forty chronic hemodialysis patients (mean age 54.7 years; 87.5% African Americans; 45% females) were studied. High metabolic rate compartment expressed in percent of body weight was inversely related to body weight (r=-0.475; P=0.002) and body mass index (r=-0.530; P<0.001). In a multiple linear regression model, protein catabolic rate was significantly correlated only with high metabolic rate compartment (r=0.616; P<0.001). Assuming that protein catabolic rate in addition to protein intake reflects urea and uremic toxin generation, it follows that high metabolic rate compartment is the major compartment involved in their generation. Consequently, uremic toxin production rate may be relatively higher in patients with low body weight and low body mass index as compared to their heavier counterparts. The poorer survival observed in smaller dialysis patients may be related to these relative differences.

Adult↗
PubMed1996

Assessment of body composition in youths and relationship to sport.

Body composition assessment techniques provide estimates of percent body fat (%BF), fat mass (FM), and fat-free mass (FFM) based on indirect assessment models and methods. Prediction equations for %BF developed using a two-component model based on adult body composition constants with overestimate %BF in youths, especially prepubescent youths. Body composition prediction equations that have been validated and cross-validated using multiple-component criterion models which include measurements of body density and the water and mineral components of FFM provide the most accurate means for assessment of body composition in youths. Use of appropriate prediction equations and proper measurement techniques, for either bioelectrical impedance or skinfolds, results in body composition estimates with standard errors of estimate (prediction errors) of 3 to 4% BF and 2.0 to 2.5 kg of FFM. Poor measurement technique and inappropriate prediction equations will result in much larger prediction errors.

Adipose Tissue↗
PubMed1988

Growth and body composition of mice selected for high body weight.

To elucidate the influence of high body weight selection on body compositional relationships, the accumulation of lipid, protein, and ash was investigated in two lines of mice selected for high 42-day body weight (H lines) and an unselected foundation population (FP). The two H lines differed in population size and were designated as the high-large (HL) and high-small (HS) lines. Logistic body growth curves revealed that HL mice exhibited an accelerated growth rate and reached a higher mature body weight than FP or HS mice. Over the range of body weights examined, HL mice had more lipid, less protein, and less ash than FP or HS mice of the same sex and body weight. However, HL lipid accumulation (relative to body weight increase) was not accelerated in comparison to that of FP mice. This study suggests that the existing model of selection-mediated compositional changes requires expansion to account for the ability of high-growth selection to direct an acceleration of body growth without a correlated enhancement of the relative rate of fat accumulation.

Aging↗
PubMed1978

Postnatal changes in body composition of laboratory maintained brown lemmings, Lemmus sibiricus.

Postnatal changes in the body composition components, namely, body water, fat-free dry solids, and fat, were determined for laboratory-maintained brown lemmings, Lemmus sibiricus. The proportion of body water decreased while the proportion of fat-free dry solids and fat increased from birth to approximately 15 weeks of age. From 20 through 80 weeks of age, the proportions of all body composition components as well as total body weight remained relatively constant. Body composition components were more closely correlated with body weight than with chronologic age. As a function of body weight, body water decreased while fat-free dry solids and fat increased. Body fat was the most variable body composition component as related both to body weight and chronologic age. The von Bertalanffy growth equation and the differential growth equation were used to describe the body composition component data as related to chronologic age and body weight, respectively.

Animals↗
PubMedDate not supplied

Percentiles of body composition from bioelectrical impedance and body measurements in U.S. adolescents 8-17 years old: Project HeartBeat!

Reference percentiles (5th, 10th, 50th, 85th, 90th, and 95th) of black and nonblack children ages 8-17 years from Project HeartBeat! (n = 678) are presented for body mass index (BMI), percent body fat (PBF), fat-free mass (FFM), and fat mass (FM) derived from bioelectrical impedance. Project HeartBeat! is a mixed longitudinal study in which three cohorts of children (seen initially at age 8, 11, or 14 years) were followed for 4 years and measured thrice-yearly from 1991 through 1995. Weight, height, and BMI of Project HeartBeat! children are similar in central tendency and variability to those of nationally representative samples for nonblack children but not black children, for whom there is an excess of children at or above the 95th percentile for weight and BMI. Values of PBF above which cardiovascular risk variables increase (as suggested in the literature) are located at the 85th percentile of the Project HeartBeat! distributions. This percentile of PBF may be tentatively considered as a cutoff point with epidemiological significance for children.

Adolescent↗
PubMed2002

Segmental bioelectrical impedance analysis in children aged 8-12 y: 2. The assessment of regional body composition and muscle mass.

OBJECTIVES: To investigate the potential of segmental bioelectrical impedance analysis (BIA) for assessing regional composition and muscle mass in children. DESIGN: Strengths of relationships were determined between (a) BIA indices of trunk, limbs or limb segments and (b) segment fat or fat-free mass (FFM) assessed using dual-energy X-ray absorptiometry (DXA); the extent of agreement was established between two independent models, based on DXA and BIA, of limb muscle and adipose tissue (AT) mass. SUBJECTS: Eighteen boys and 19 girls aged 8-12 y. MEASUREMENTS: BIA and anthropometry of trunk, whole limbs, limb segments and defined sections were used to calculate segmental impedance indices and specific resistivities; segment fat and FFM were obtained using DXA; muscle and AT masses of limbs, segments and sections were estimated using DXA and BIA models, and by anthropometry. RESULTS: Segmental BIA indices were significantly related to composition of the segments assessed using DXA; although substantial bias was observed, there was fairly good agreement (low 95% limits of agreement) between the BIA and DXA models of muscle mass and estimates from each were similarly categorised in tertiles, as were estimates of AT. CONCLUSION: Segmental BIA appears to have potential for assessing in children the composition of body segments, as obtained using DXA, and the masses of muscle and AT in whole limbs, limb segments and defined sections.

Absorptiometry, Photon↗
PubMed1991

Basal metabolic rate, body composition and whole-body protein turnover in Indian men with differing nutritional status.

1. Three groups of adult men were studied in Bangalore, India: two groups were controls who had been receiving an adequate diet. Of these, one group, designated 'normal weight controls', had a mean body mass index of 22; the other group, 'underweight controls', had a mean body mass index of 16.7. The third group consisted of poor labourers, whose daily food intake had been less than 10 MJ and whose mean body mass index was 16.6. Previous studies had shown that such men had a lower basal metabolic rate than well-nourished Indian control subjects. 2. The object of the present study was to find out whether a reduced rate of protein turnover, measured after a single dose of [15N]glycine, contributed to a lower basal metabolic rate. It was found, however, that after adjusting for body weight and fat-free mass by analysis of co-variance there was no significant difference in basal metabolic rate between the three groups. Adjusted rates of protein synthesis were higher in the underweight controls and the undernourished labourers than in the normal weight controls, but not significantly so. 3. Estimates based on creatinine excretion showed that within the fat-free mass the underweight groups had a higher proportion of non-muscle to muscle mass. This may explain the somewhat higher rates of protein turnover in these groups. 4. Nitrogen flux (Q) was determined from 15N abundance in two end products, urea (QU) and ammonia (QA). In the underweight and undernourished groups the ratio QU/QA was increased compared with the normal weight group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

[Protein quality of dietary yeast ribonucleic acid in experiments using growing rats. 1. Effect of ribonucleic acid on the body composition].

In a feeding trial with growing rats the influence of dietary ribonucleic acid on the composition of body gain was investigated. To a control ration with casein + 50% DL-methionine as the sole protein source (1,64 N% in DM) ribonucleic acid (RNA) from yeast was supplemented at four levels ranging from 7,8% to 31,2% of diets nitrogen. The portion of daily feed and nitrogen intake derived from the basal diet was designed to be equal for all the animals. RNA was ingested in addition. Gain of body fresh and dry matter slightly increased with the dietary RNA-level, due to an increased deposition of body fat. Protein efficiency ratio as well as productive protein value decreased linearly with increasing N-intake. It may be concluded that RNA-N has slightly contributed to body mass gain but was not utilised for protein deposition.

Animals↗
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↗
PubMed1991

[Sports activity and body composition. Study by whole body osteodensitometry of 269 men between 17 and 21 years of age].

Two hundred and sixty one men aged between 17 and 21 were questioned concerning their sports activities and underwent "whole body" osteodensitometry. Values found in terms of bone density rose harmoniously and proportionally from the ages of 17 to 21. Studied in terms of sports activities claimed, figures were higher in athletes and this essentially concerning the lower limbs and pelvis. These data contrast a "growth" effect with a "physical activity" effect, the first being of a systemic nature involving total bone mass and the second of a locoregional nature concerning only those bone segments involved in a particular activity. Our study failed to reveal any arguments in favour of spinal bone steal to the advantage of the lower limbs in athletes. The authors feel that "whole body" osteodensitometry by simultaneous and prospective study of bone segments involved or not involved in exercise should enable a distinction to be drawn between the systemic and locoregional effects of physical activity and thus, in the context of primary prevention, to define the optimal calcium intake and physical activity leading to acquisition of maximum bone capital and to maintain it to the best possible extent.

Absorptiometry, Photon↗