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Biomedical subjects

S B Heymsfield

Publications and source records attributed to S B Heymsfield.

At least 199 records · Page 11Linked to original sources
PubMed1990

Metabolic abnormalities in bulimia nervosa.

Resting metabolic rate was measured in a group of 22 women of normal body weight with bulimia nervosa and in 19 age-, sex-, and weight-matched control subjects. Mean resting metabolic rate of patients was significantly lower than that of controls (5162 +/- 928 vs 5636 +/- 449 kJ/24 h [1229 +/- 221 vs 1342 +/- 107 kcal/24 h]), as was mean fasting blood glucose level (4.0 +/- 0.6 vs 4.6 +/- 0.6 mmol/L). Mean basal thyrotropin level was significantly lower in patients than controls, but other thyroid indexes did not differ. There were no group differences in body fat mass, fat cell size, or lipoprotein lipase activity. These data suggest that there is a disturbance in energy regulation in bulimia nervosa. However, the origins and role of this disturbance in the pathophysiology of bulimia are unclear.

Adipose Tissue↗
PubMed1990

High precision in-vivo neutron activation analysis: a new era for compartmental analysis in body composition.

We have focused on two topics in body composition research. The first is basic: we must quantitatively define the interrelationships of the body compartments to one another in health before studying these relationships in disease. The precisions now available can enable us to get to do this work, over the full range of age, race, and occupational diversity. The second direction is more modest and more technical, but nonetheless important. It is the calibration and validation of surrogate measurement methods suitable for field research conditions, doctors' offices, intensive care units, etcetera. Our methods have advanced in fundamental ways. We have an obligation to see them applied effectively.

Adipose Tissue↗
PubMed1990

Body composition of humans: comparison of two improved four-compartment models that differ in expense, technical complexity, and radiation exposure.

Multicompartment models are of growing importance in the study of body composition in humans. This study compares two improved four-compartment (water, protein, mineral, and fat) models that differ in expense, technological complexity, and radiation exposure. Primary data (from 31 subjects) for the first model were derived by dual-photon absorptiometry, 3H2O dilution, and hydrodensitometry and for the second model by delayed and prompt gamma neutron-activation analysis and 3H2O dilution. Estimates of fat, protein, and mineral from the first model were highly correlated with those from the second model (r = 0.98, 0.72, and 0.94, respectively; all p less than 0.001). The proportions of body weight represented by water, protein, mineral, and fat for the simpler first model (0.532, 0.155, 0.048, and 0.265) were similar to compartment fractions provided by the more complex and costly second model (0.532, 0.143, 0.046, and 0.279). Multicompartment body composition models can thus be developed from increasingly available techniques that compare favorably with similar results derived from limited-access instrumentation.

Absorptiometry, Photon↗
PubMed1990

Appendicular skeletal muscle mass: measurement by dual-photon absorptiometry.

Dual-photon absorptiometry (DPA) allows separation of body mass into bone mineral, fat, and fat-free soft tissue. This report evaluates the potential of DPA to isolate appendages of human subjects and to quantify extremity skeletal muscle mass (limb fat-free soft tissue). The method was evaluated in 34 healthy adults who underwent DPA study, anthropometry of the limbs, and estimation of whole-body skeletal muscle by models based on total body potassium (TBK) and nitrogen (TBN) and on fat-free body mass (FFM). DPA appendicular skeletal muscle (22.0 +/- 3.1 kg, mean +/- SD) represented 38.7% of FFM, with similar proportions in males and females. There were strong correlations (all p less than 0.001) between limb muscle mass estimated by DPA and anthropometric limb muscle areas (r = 0.82-0.92), TBK (r = 0.94), and total-body muscle mass based on TBK-FFM (r = 0.82) and TBK-TBN (r = 0.82) models. Appendicular skeletal muscle mass estimated by DPA is thus a potentially practical and accurate method of quantifying human skeletal muscle mass in vivo.

Absorptiometry, Photon↗
PubMed1990

Overfeeding: cardiovascular and metabolic response during continuous formula infusion in adult humans.

The cardiovascular and metabolic response to continuous nasoenteric formula infusion was monitored in eight healthy men during three consecutive 1-wk balance periods: maintenance-stabilization, overfeeding at twice the maintenance infusion rate, and postoverfeeding return to maintenance infusion. Elemental balance, thermogenic, and stable-isotope studies carried out throughout protocol identified 1) two distinct phases during overfeeding (early, days 1-4, and late, days 4-7); 2) changes in extracellular fluid (sodium balance) as the major determinant of overfeeding weight gain; 3) individual differences in percentage of excess fuels retained during overfeeding (76-87%), derived from variation in both digestive and thermogenic processes; and 4) a sustained physiologic response during the postoverfeeding period. These initial findings suggest that individuals differ in response to overfeeding and that specific aspects of this variation are amenable to future study. In addition, the timing of observed fluid, metabolic, and cardiovascular changes during overfeeding suggests specific strategies aimed at preventing refeeding circulatory complications.

Adult↗
PubMed1990

Height-normalized indices of the body's fat-free mass and fat mass: potentially useful indicators of nutritional status.

Expressing fat-free mass (FFM) and body fat mass (BFM) as percentages of body weight or by weight is unsatisfactory. For example, tall patients with protein-energy malnutrition (PEM) can exhibit values for FFM and BFM similar to those of shorter well-nourished individuals. To obviate such difficulties, we propose use of height-normalized indices, namely, a FFM index [FFM (kg)/height (m)2, or FFMI] and a BFM index [BFM (kg)/height (m)2, or BFMI]. We calculated these indices in a reference population of 124 healthy young men and in 32 nonobese young men (from the Minnesota Study) before, during, and after experimental semistarvation. When values for FFMI and BFMI falling below the reference cohort's 5th percentile cutoff point were used as a criterion for PEM, these indices, together with basal oxygen-consumption rate, diagnosed PEM in 27 of the 32 Minnesota Study subjects after 12 wk of semi-starvation. These findings indicate that FFMI and BFMI may be useful in nutritional assessment.

Adipose Tissue↗
PubMed1990

New approaches to body composition research: a reexamination of two-compartment model assumptions.

The field of human body composition research by necessity is based upon assumptions related to tissue chemical content. The 2-compartment model, which requires only 1 measurement in addition to body weight, is the cornerstone of current research in this field. Yet the assumptions upon which 2-compartment models are based were developed on a limited scale and their validity under specified conditions is questionable. Recent developments now allow quantification of previously unmeasured somatic constituents. The capacity to extend our models to 4 or more components is now at hand. Not only will this allow us to vastly expand our validation of two 2-compartment approaches, but our ability to explore new and important physiological questions is within reach.

Adipose Tissue↗
PubMed1989

Rate of weight loss during underfeeding: relation to level of physical activity.

The kinetics and bioenergetic-metabolic determinants of weight loss were examined in obese women ingesting 900 kcal/d for 5 weeks. The patients were assigned either to a sedentary group (n = 5) or to an exercise group (n = 6) in which the participants expended an additional (X +/- SD) 346 +/- 61 kcal/d in aerobic physical activity. The percentage weight loss and the fractional rates (K1 = fast component; K2 = slow component) of weight loss were almost identical between the two groups. The failure of added exercise to increase the velocity of weight loss could not be explained by differences between the groups in any of the following: gastrointestinal energy and nitrogen (N) absorption; fractional rates of urinary urea N and total N loss; or the thermic effect of the formula diet. The cumulative and fractional rates of protein (ie N) loss were also similar between the groups. The exercise group lost more fat (5.3 +/- 1.0 kg) than the non-exercise group (4.4 +/- 1.6 kg, P less than .001) as measured by underwater weighing. The maximum between-group difference in the rate of fat loss, as determined by energy-N balance, occurred during early underfeeding. With continuation of the 900 kcal/d diet, the between-group differences in the rate of fat loss diminished. The exercise subjects significantly lowered their resting heat losses relative to the non-exercise subjects (P less than .025). This in turn reduced the degree of negative energy balance in the more energy-deficient exercise group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Ethanol: relative fuel value and metabolic effects in vivo.

A nasogastric formula infusion method was used to evaluate the steady-state fuel value of ethanol relative to that of glucose in eight chronically alcoholic men undergoing a 4- or 5-week balance experiment. Each subject received a maintenance infusion of the formula diet throughout the study. When control formula glucose (week 1) was isocalorically replaced with ethanol [week 2, 30% of kcal; week 3 or 4 (5-week experiment) 40% to 60% of kcal], the following was observed: weight loss; zero energy balance and reduced or negative balances of N, K, P, Mg, and Na; increased urinary urea N and 3-methylhistidine; lowered urinary C-peptide; no change in indirectly or directly measured thermal energy losses; and a blood level related rise in breath and urinary ethanol losses. All of these changes promptly reversed during the middle (week 3 in 5-week experiment) and final control weeks. Accounting for all diet-related energy losses (urine, breath, thermal), the fuel value of the ethanol-containing diet relative to the glucose control formula varied between 0.95 and 0.99, depending upon the blood alcohol level. Hence weight loss during short-term (seven-day) ethanol infusion is unrelated to overall negative energy balance, stems primarily from decrements in protein, minerals, and fluid, and may in part be mediated by the reduction in insulin secretion that accompanies switching from dietary glucose to ethanol.

Adult↗
PubMed1989

Dual-photon absorptiometry: comparison of bone mineral and soft tissue mass measurements in vivo with established methods.

This study extended initial observations that indicated the potential of dualphoton absorptiometry (DPA) to measure total-body bone mineral (TBBM) and fat in vivo. DPA-derived TBBM and fat were compared with established methods in 13 subjects (aged 24-94 y) who underwent measurement of body density (Db), total-body water (TBW), potassium (TBK), calcium (TBCa, delayed-gamma neutron activation), and nitrogen (prompt-gamma neutron activation). TBBM was highly correlated with TBCa (r = 0.95, p less than 0.001) and the slope of TBCa vs TBBM (0.34) was similar to Ca content of ashed skeleton (0.34-0.38). DPA-measured fat (means +/- SD, 16.7 +/- 4.9 kg) correlated significantly (r = 0.79-0.94; p less than 0.01-0.001) with fat established by Db (16.3 +/- 5.4 kg), TBW (16.0 +/- 4.3 kg), TBK (17.7 +/- 4.6 kg), combined TBW-neutron activation (17.6 +/- 5.9 kg), and means of all four methods (16.9 +/- 4.8 kg). DPA thus offers a new opportunity to study human skeleton in vivo and to quantify fat by a method independent from the classical assumption that bone represents a fixed fraction of fat-free body mass.

Adipose Tissue↗
PubMed1989

Congestive heart failure: clinical management by use of continuous nasoenteric feeding.

Congestive heart failure (CHF) is often associated with undernutrition. Although loss of lean tissue may be detrimental to the host, a protective effect is conveyed as cardiac demands are reduced by lower whole-body oxygen consumption (VO2) and circulating fluid volume. The aim of this study was to determine if continuous nasoenteric feeding could promote an anabolic state with increments in lean tissue in moderate-severe CHF patients without adversely effecting cardiac performance. Undernourished CHF patients on a metabolic ward were fed a formula diet infused intragastrically for 2 wk. The energy infusion rate was maintained at 1.4-1.8 X measured resting metabolic rate. During the infusion period, body weight, elemental balances, VO2, and cardiac function (echocardiography) were monitored. Results showed a loss in weight and extracellular fluid, gain in lean body mass (eg, + delta N and delta K), unaltered VO2, and unchanged cardiac function. Cardiac cachexia is therefore safely and effectively manageable by maintenance or repletional levels of nasoenteric feeding.

Body Weight↗
PubMed1989

Body composition in elderly subjects: a critical appraisal of clinical methodology.

Body composition measurements are integral to nutritional assessment of elderly subjects. The validity of methods available for partitioning body weight into its tissue or chemical subfractions in the geriatric population is of primary importance. Until recently verifying the accuracy of body composition techniques in vivo was limited by prevailing technology. New advances such as neutron activation analysis, neutron inelastic scattering, and dual photon absorptiometry now promise to overcome these earlier limitations. With these new tools investigators can now examine critical underlying assumptions related to body composition assessment in elderly subjects. This review highlights the need and opportunities for future research in this area.

Aged↗
PubMed1989

Chemical determination of human body density in vivo: relevance to hydrodensitometry.

A chemical approach to establishing human body density in vivo was developed by combining recently developed noninvasive methods. Four compartments were measured: protein (P; prompt-gamma neutron activation), water (A; 3H2O dilution), mineral (M; dual-photon absorptiometry and delayed-gamma neutron activation), and fat (F; dual-photon absorptiometry). By this model body weight is equal to P + A + M + F. This approach was applied to 13 healthy adults (8 females and 5 males). The four compartments accounted for greater than 97% actual body weight. Calculated density based upon composition agreed within 0.6 +/- 0.4% (mean +/- SD) with density (D) measured by hydrodensitometry [calculated D (g/cc) = 0.86 measured D +0.15; r = 0.94, p less than 0.001]. The average calculated lean (P + A + M) density of 1.096 +/- 0.007 g/cc agreed closely with three classic human cadaver studies (1.100 g/cc). This multicompartment approach provides a new opportunity to estimate human body density in vivo and to refine body composition methods based upon an assumed but inadequately validated constant lean density.

Absorptiometry, Photon↗