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Biomedical subjects

S B Heymsfield

Publications and source records attributed to S B Heymsfield.

At least 217 records · Page 12Linked to original sources
PubMed1989

Body fat from body density: underwater weighing vs. dual-photon absorptiometry.

We measured fat in 286 healthy volunteers by underwater weighing (FUWW) and dual-photon absorptiometry (FDPA) to develop a translation table for the differing results from these entirely different techniques and to study the sources of these differences. In 99 males and 187 females aged 19-94 yr, fatness was 7-47%. Prediction equations are presented for FUWW-FDPA (delta F), density of lean body mass (DLBM), and FDPA. FUWW and FDPA were significantly different from each other (P less than 0.01). Calculated DLBM is less than the assumed constant of 1.10 (P less than 0.01), ranging widely from 1.05 to 1.13 and being highly correlated with the ratio of total body bone mineral to lean body mass (TBBM/LBM). delta F, the differences between FUWW and FDPA measurements in individual subjects, varied widely (-7 to +11% in males and -18 to +13% in females). The difference was positively correlated with the DLBM. FUWW was no better than anthropometrics in equations for predicting FDPA. The FDPA predicted from anthropometrics showed smaller standard errors than when FUWW was used. Neither anthropometrics nor FUWW equations are clearly superior to those previously available.

Adipose Tissue↗
PubMed1988

Continuous nasoenteric feeding: bioenergetic and metabolic response during recovery from semistarvation.

The bioenergetic and metabolic response to continuous nasoenteric feeding was examined under balance conditions for up to 22 d in 12 stable undernourished medical patients. Each subject received a fixed inflow of the mixed-fuel formula at rates of one to three times maintenance energy requirement. The pooled results were used to develop a composite profile of physiologic changes during recovery from semistarvation. Body weight, whole-body gas exchange, minute ventilation, thermal and chemical energy losses, and balances of energy, nitrogen, potassium, and sodium changed as a function of formula infusion rate and duration of feeding. These component measurements allowed calculation of such classic bioenergetic efficiency terms as digestible, metabolizable, and net energy as functions of infused energy (IE, kcal.kg fat free body mass-1.h-1: 0.96IE, 0.93IE, and 6.7 [1 - e-0.16IE], respectively) and the energy content of weight gain (means +/- SD; early, 4.2 +/- 3.5 kcal/g, and later, 7.4 +/- 3.6 kcal/g). Continuous nasoenteric feeding provides a unique opportunity to define previously unexplored dietary and metabolic interrelations in humans.

Adult↗
PubMed1988

Biennial survey of physician clinical nutrition training programs.

This is the third survey of physician clinical nutrition training programs. Current training programs were identified, descriptive information obtained, and training program content was compared with that recommended at the 1984 Conference on Clinical Nutrition Training. In general, goals as to the quantity of research, clinical, and teaching training are being met. Virtually all programs provide training in nutritional support activities. Most training programs are not as broad in scope of exposure to the less clinical aspects of nutrition nor to all the illness and age groups recommended by the 1984 conference. Consideration of broadening the scope of physician training programs or redefinition of training guidelines is warranted. A program-certifying agency may be helpful in identifying programs achieving certain minimal standards.

Curriculum↗
PubMed1988

Abdominal composition quantified by computed tomography.

Abdominal composition was quantified from computed tomography (CT) scans of 96 clinically normal men and women aged 20-83 y. Measurements were taken of total and intraabdominal areas and of muscle, bone, and subcutaneous and intraabdominal adipose-tissue areas from each of six 8-mm-thick transverse slices from CT images of abdomen and pelvis. Men had a significantly greater percentage of intraabdominal adipose tissue than women and the percentage increased with age in each sex. Percentages of total abdominal area that were adipose tissue were significantly negatively correlated with percentages of muscle and bone in each sex. Ratios of total areas of abdominal slices to total areas of pelvic slices (analogous to waist:hip ratios) had significant positive correlations with the absolute and relative areas of intraabdominal and subcutaneous adipose tissue for the abdomen in women but not in men. These ratios also had significant negative correlations with absolute and relative areas of muscle and bone in women.

Abdomen↗
PubMed1987

Physiologic response and clinical implications of nutrition support.

Cardiopulmonary complications such as sudden death, congestive heart failure and hypercapnia are now recognized to punctuate the refeeding course of malnourished hospitalized patients; these effects in particular occur early in the recovery period. Data that indicate a time-dependent dose and composition effect of continuously infused formula on gas exchange, metabolic rate, ventilation and cardiac-related indexes are discussed. Unlike the interrupted feeding of regular meal ingestion, continuous feeding produces a sustained physiologic response. Delineation of continuous feeding effects on host metabolism provides a rational basis for managing the untoward cardiac and pulmonary complications of nutrition support.

Cardiovascular Physiological Phenomena↗
PubMed1987

Bioenergetic and metabolic response to continuous v intermittent nasoenteric feeding.

Resting thermal energy losses and metabolic balances of N, K, P, Ca, Na, and Mg were compared during continuous and intermittent nasoenteric formula infusion in four healthy men. Each feeding protocol lasted 1 week in a 4-week double crossover experiment. The initial feeding schedule was established randomly. Continuous nasoenteric formula infusion produced no increase in thermal energy losses above the fasting level; energy expenditure fell with sleep to the same extent as with intermittent feeding. Thermal losses were similar during intermittent feeding with the exception of the thermic effect of food that produced an additional average energy loss of 115.7 kcal/d. The total resting and sleeping 24-hour energy expenditure was significantly lower (P less than .01) during continuous formula infusion (means +/- SD for n = 8 balance periods, 1344 +/- 119 kcal) compared to intermittent feeding (1457 +/- 179 kcal). No significant differences in nutrient absorption or balances of N, Na, Ca, and Mg were detected between the two feeding protocols. In contrast, continuous infusion of formula was accompanied by negative balances of K and the cytosolic portion of P; weight balance was slightly negative. Weight, K, and cytosolic P balances were all positive during intermittent feeding (P = NS, less than 0.01, and P less than .05 compared to respective continuous infusion periods). Hence, 1 week of continuous nasogastric formula infusion is associated with similar nutrient absorption, a significant reduction in thermal energy losses, and equivalent protein (N) balance relative to intermittent feeding. Differences in weight balance between the two feeding protocols can be ascribed largely to fluid and mineral shifts. These results suggest that energy requirements are lower during continuous formula infusion by about 100 kcal/d compared to regular meal ingestion.

Adult↗
PubMed1987

Energy expenditure during continuous intragastric infusion of fuel.

Influence of intragastric formula infusion rate on resting thermogenesis was evaluated in 24 healthy subjects. Metabolic rate (M) was measured by indirect calorimetry following an overnight fast. Subgroups then received a continuous intragastric infusion of a formula diet at three levels: submaintenance (mean +/- SEM, 1.02 +/- 0.04 times fasting M, n = 6), maintenance (1.39 +/- 0.01 times fasting M, n = 20), or supramaintenance (2.77 +/- 0.2 times fasting M, n = 14). Formula inflow was started in the evening, and intraprandial M was measured throughout the following day. Relative to fasting, submaintenance and maintenance infusions produced no detectable change in M. With supramaintenance infusion, M increased significantly (10.1%, p less than 0.05) above fasting level. Hence during continuous formula infusion a rise in M above fasting occurs only when rate of energy infusion exceeds rate of thermal energy losses. These results have implications in regard to energetic efficiency of continuous fuel infusion relative to intermittent food or formula ingestion.

Adult↗
PubMed1986

High-carbohydrate diet: antinatriuretic and blood pressure response in normal men.

The hypothesis that high-carbohydrate feeding leads to increased insulin secretion, sodium retention, and elevation in blood pressure was examined in seven healthy men. A baseline 7-day balance study on low (13%) or high (52%) carbohydrate was followed by a 2-wk balance on the alternate diet and a 1-wk balance on the baseline diet. Results indicated that changing carbohydrate intake caused a rapid (2-3 day) inverse change in urinary sodium excretion and balance. By the second week, however, urinary-sodium level returned to baseline accompanied by an inverse change in plasma aldosterone. No significant rise in blood pressure was detected throughout the study. High-carbohydrate feeding promotes sodium retention in normal subjects, but the effect is counterregulated by a reduction in plasma aldosterone. A high-carbohydrate diet in healthy subjects does not cause a significant short-term increase in blood pressure.

Aldosterone↗
PubMed1985

Tissue components of weight loss in cancer patients. A new method of study and preliminary observations.

A new approach using anthropometric, radiographic, biochemical, and ultrasonic methods allowed partition of body weight into fat, fat-free mass, skeletal muscle, and volume of heart, liver, kidneys, spleen, and tumor. These methods were used to evaluate body composition longitudinally in a pilot group of nine cancer patients, seven of whom lost weight (greater than 2.5 kg) during the study period. Two control groups also underwent the protocol: (1) healthy subjects (+/- 10% IBW) of similar age, sex, and height; and (2) patients with weight loss due to anorexia nervosa. Weight loss in both the cancer and anorexia nervosa groups could be accounted for primarily by loss in fat and skeletal muscle; although the relative magnitude of these tissue losses were approximately the same in both groups, cancer patients lost relatively less body weight. This was because (1) overt or occult ascites (detected radiographically) was present in cancer patients (3 of 9); (2) tumor bulk increased fat-free mass by up to 1 to 2 kg; and (3) the proportional loss in visceral organ volume was less in cancer patients than in anorexia nervosa patients. In the latter group, heart, liver, kidneys, and spleen were reduced in proportion to body weight, whereas in the cancer group as a whole, these organs (when uninvolved with tumor) lost little (heart and kidneys) or no volume (liver and spleen). This initial study suggests that the principal endogenous energy and nitrogen sources during evolution of weight loss in cancer are primarily adipose tissue triglycerides and skeletal muscle proteins. In some cancer patients, fluid accumulation, a large tumor burden, and the slow rate of visceral organ atrophy make body weight an unreliable index of available energy-nitrogen reserves.

Adipose Tissue↗
PubMed1985

The effect of a phenylalanine and tyrosine restricted diet on elemental balance studies and plasma aminograms of patients with disseminated malignant melanoma.

Previous studies indicate dietary phenylalanine and tyrosine restriction may be of value in managing advanced cancer patients. To further evaluate this approach, we performed a 60-day study in which four patients with advanced malignant melanoma received formula diets via nasogastric tube containing only 8 mg total phenylalanine and tyrosine per kg lean body mass per day. Two of three patients completing elemental balance studies were in negative nitrogen, potassium, and phosphorus balance, suggesting an essential nutrient deficiency. Three patients tolerated the diet well, but one was non-compliant. Although no serious toxicity developed, serum albumin, total iron binding capacity and cholesterol significantly decreased (p less than 0.01) in the three complaint patients. Fasting plasma phenylalanine and tyrosine values did not significantly change during the study, but two-hour postprandial plasma phenylalanine and tyrosine concentrations fell below normal and were significantly lower than preprandial levels (p less than 0.01). There were no tumor responses.

Adult↗
PubMed1985

Biennial survey of physician clinical nutrition training programs.

A survey was conducted of 50 medical centers providing postgraduate clinical training in nutrition. Each program director completed a questionnaire that requested information on major program affiliations and interests, available positions, number of trainees, sources and level of funding, and general aspects of the curriculum. The results are assembled into a geographic listing of the 50 centers, and the tabulated data provides a current profile of postgraduate clinical training in nutrition.

Directories as Topic↗
PubMed1985

Human energy requirements: overestimation by widely used prediction equation.

Basal energy expenditure accounts for a large component of energy losses, and a clinical estimate of this form of thermogenesis is usually derived from a prediction equation. The most widely used prediction equation was developed in 1919 by Harris and Benedict. The energy requirements of healthy and diseased individuals are often estimated from application of this formula. Using a direct gradient-layer calorimeter and two different indirect calorimeters, our two centers found that the Harris-Benedict equation overestimated basal energy requirements by 10 to 15% (X +/- SD, 12.3 +/- 11%) in 201 studies of healthy men and women. These results raise questions regarding the accuracy of predicting an individual's energy requirements.

Adolescent↗
PubMed1985

A new approach for studying the thermic response to dietary fuels.

We describe a new method of studying the thermic response to dietary fuels that involves continuous infusion of a liquid formula diet through a thin nasogastric tube. The data show that the steady inflow of dietary fuel is accompanied by a relatively constant level of energy expenditure, the magnitude of which depends on the rate of fuel inflow. An increase in the rate of fuel infusion above that required for caloric maintenance leads to a rise in energy expenditure. We also give examples, based on preliminary observations, of how the technique can be used to more precisely quantify energy metabolism. The technique may prove useful in the studying efficiency of energy utilization and in examining the extent to which individuals differ in energy efficiency.

Adult↗
PubMed1985

Thermic effect of food after ingested versus tube-delivered meals.

We compared, in six subjects, the thermic effect of food (TEF) after the ingestion of a test meal with that observed after the delivery of an equivalent test meal directly into the stomach through a nasogastric tube. TEF was measured after each test meal (i.e., ingested or tube delivered) until postprandial metabolic rate was not different from fasting metabolic rate (as measured at approximately the same time of day on a previous day). TEF after the tube-delivered meal was not significantly different in magnitude or duration from TEF after the ingested meal. The two types of meals also resulted in similar changes in respiratory quotient. These results suggest that the majority of TEF arises after the food reaches the stomach and that very little of TEF is produced by sensory factors or by the mechanical aspects of eating.

Adult↗
PubMed1985

Anorexia nervosa and sudden death.

Necropsy findings and electrocardiograms from three women with anorexia nervosa were reviewed. Necropsy examination failed to establish an anatomic cause of death. Electrocardiograms recorded days or less before death showed various degrees of Q-T interval prolongation: Q-T intervals corrected for heart rate measured 0.61 s, 0.47 s, and 0.46 s, respectively. Terminal ventricular tachyarrhythmias were documented in two patients, including torsade de pointes in one. The necropsy and clinical findings in these three cases provide evidence that sudden death in anorexia nervosa, like sudden death in liquid-protein dieting, may result from ventricular tachyarrhythmias related to Q-T interval prolongation. For such patients, electrocardiographic monitoring should be routine.

Adult↗
PubMed1984

Meal size and thermic response to food in male subjects as a function of maximum aerobic capacity.

The relationship between size of a mixed, liquid meal and the thermic effect of food (TEF) was studied in two groups of nonobese male subjects differing in maximum aerobic capacity (VO2 max). A design using repeated measures was chosen in which each subject received each meal (water, 500 kcal, 1000 kcal, 1500 kcal) on a different morning. TEF was measured by indirect calorimetry for three hours following each meal and was found to increase systematically, in a nonlinear fashion, as meal size was increased. Subjects with a high VO2 max responded to the two higher calorie meals with a greater TEF than did subjects with a low VO2 max. They also showed a greater increase in TEF for any given increase in meal size. This study establishes a precise relationship between meal size and the thermic effect of food. It also identifies an important variable, VO2 max, in determination of the individual thermic response to food. These findings suggest that individuals with a high VO2 max (such as aerobically trained athletes) show a greater caloric expenditure after eating, particularly after a large meal, than do individuals with a low VO2 max. A high thermic response to food could be beneficial in body weight homeostasis.

Adolescent↗