Body composition and aging: a study by in vivo neutron activation analysis

Human body composition can be organized into five levels; atomic, molecular, cellular, tissue-system and whole body. Six elements (carbon, nitrogen, calcium, potassium, sodium and chlorine) can be directly measured in vivo at the atomic level using three neutron-activation systems at Brookhaven National Laboratory. When combined with an estimate of total body water, the six elements can be used to quantify the major chemical components at molecular level. In the present report, we first describe the neutron-activation approach to evaluating chemical compartments in vivo. Then, we present an example of how in vivo estimates of human chemical composition can be used to study the validity of two-compartment indirect methods of quantifying total body fat in the elderly. Our studies and the work of other investigators at Brookhaven National Laboratory suggest that neutron activation analysis provides an important opportunity to study the relation between aging and changes in elemental and chemical composition of humans in vivo.

Aging and body composition: possibilities for future studies

Three approaches are being taken to the development of techniques for measuring body composition: 1) improving present methods, 2) formulating and devising new body composition measuring techniques and 3) focusing on specific problems of body composition changes in aging. The improvement of multi-frequency bioelectrical impedance, computerized tomography, magnetic resonance and dual-photon absorptiometry imaging belong under the first category. Recent developments in low radiation exposure measurement of body carbon and oxygen by neutron inelastic scattering and body protein by gamma-ray resonance are examples of new technology applied to the direct assessment of body composition of the elderly. The third category remains the most important one and should motivate the evolution of existing methods and the development of new. Current questions focus on distribution of regional body fat and its role in cardiovascular diseases and the depletion of lean body mass with age and its relation to functional capacity, quality of life and resistance to injury or disease. The relationship between the distribution of fat, the depletion of muscle tissue and changes in cellular function with age will become the focus of the future studies of body composition.

Age-related differences in body composition by hydrodensitometry and dual-energy X-ray absorptiometry

To determine whether percent body fat (%BF) is overestimated in older people by hydrodensitometry (HD) because of an age-related decrease in bone mineral content (BMC), body composition of 113 women and 72 men (21-81 yr) was assessed by HD and dual-energy X-ray absorptiometry (DEXA). DEXA provides an estimate of %BF adjusted for differences in BMC. HD %BF and DEXA %BF were not different in young people [21-39 yr; 17.6 +/- 6.4 (SD) vs. 17.6 +/- 7.2%, NS], were slightly, but significantly, different in middle-aged people (40-59 yr; 25.5 +/- 6.4 vs. 24.1 +/- 6.7%, P < 0.05), and showed the largest disparity in older people (> or = 60 yr; 34.9 +/- 7.9 vs. 30.8 +/- 8.7%, P < 0.05). The discrepancy in older people was apparently not due to mineral loss, however, inasmuch as correction of HD %BF for variance in BMC as a fraction of fat-free mass resulted in only small adjustments (approximately 1%) of %BF. Assessment of DEXA %BF was further evaluated in nine subjects with packets of lard (2-3 kg) overlying either the thigh or the trunk region. Only 55% of the exogenous fat was identified as fat when it was in the trunk region compared with 96% when it was positioned over the legs. These data suggest that the age-related increase in upper body adipose tissue is underestimated by DEXA.

Sarcopenia and age-related changes in body composition and functional capacity

Advancing adult age is associated with profound changes in body composition. One of the most prominent of these changes is sarcopenia, defined as the age-related loss in skeletal muscle mass, which results in decreased strength and aerobic capacity and thus functional capacity. Sarcopenia is also closely linked to age-related losses in bone mineral, basal metabolic rate and increased body fat content. Through physical exercise and training, especially resistance training, it may be possible to prevent sarcopenia and the remarkable array of associated abnormalities, such as type II diabetes, coronary artery disease, hypertension, osteoporosis and obesity. Using an exercise program of sufficient frequency, intensity and duration, it is quite possible to increase muscle strength and endurance at any age. There is no pharmacological intervention that holds a greater promise of improving health and promoting independence in the elderly than does exercise.

Frequency of feeding, weight reduction and energy metabolism

A study was conducted to investigate the effect of feeding frequency on the rate and composition of weight loss and 24 h energy metabolism in moderately obese women on a 1000 kcal/day diet. During four consecutive weeks fourteen female adults (age 20-58 years, BMI 25.4-34.9 kg/m2) restricted their food intake to 1000 kcal/day. Seven subjects consumed the diet in two meals daily (gorging pattern), the others consumed the diet in three to five meals (nibbling pattern). Body mass and body composition, obtained by deuterium dilution, were measured at the start of the experiment and after two and four weeks of dieting. Sleeping metabolic rate (SMR) was measured at the same time intervals using a respiration chamber. At the end of the experiment 24 h energy expenditure (24 h EE) and diet-induced thermogenesis (DIT) were assessed by a 36 h stay in the respiration chamber. There was no significant effect of the feeding frequency on the rate of weight loss, fat mass loss or fat-free mass loss. Furthermore, fat mass and fat-free mass contributed equally to weight loss in subjects on both gorging and nibbling diet. Feeding frequency had no significant effect on SMR after two or four weeks of dieting. The decrease in SMR after four weeks was significantly greater in subjects on the nibbling diet. 24 h EE and DIT were not significantly different between the two feeding regimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased body fat mass and decreased extracellular fluid volume in adults with growth hormone deficiency

OBJECTIVE

Growth hormone deficiency in adults with hypopituitarism has previously received little attention. Recent data, however, suggest that GH deficiency might be essential for the long-term prognosis of these patients. Earlier studies have documented that GH regulates body composition; in this, body composition in adult patients with hypopituitarism including GH deficiency was studied.

DESIGN

A follow-up study of patients with hypopituitarism on routine replacement therapy with L-thyroxine, cortisone acetate and sex steroids.

PATIENTS

One hundred and six patients (69 males, mean age 52.5 years and 37 females, mean age 53.4 years) diagnosed as having growth hormone deficiency on the basis of low IGF-I concentration or a maximum GH-response less than 5 mU/l after an insulin/glucagon tolerance test.

MEASUREMENTS

Body composition was estimated from body weight, total body water and total body potassium and the results were compared with values predicted from height, weight, age and sex, using data from a large number of healthy subjects.

RESULTS

The total body water was significantly lower than that predicted from the observed body weight (P < 0.001), as was the extracellular water (P < 0.001) and the extracellular/intracellular water quotient (P < 0.001). On average, the body cell mass was similar to the predicted value, but the observed/predicted body cell mass ratio correlated positively with age at follow-up. The body cell mass was lower than predicted in subjects below the age of 50 years (P < 0.01). The body fat was higher than predicted (P < 0.001); the increases was also noted in lean subjects. The observed body weight in male subjects was 7.5 kg higher (P < 0.001) than that predicted from healthy subjects of the same body height, a difference explained by an average increase of 6.6 kg in the body fat (P < 0.001) and 1.6 kg in the body cell mass, with a simultaneous reduction of 0.7 kg in the extracellular water (NS). Male patients suffering from untreated androgen deficiency had lower body cell mass than those on androgen treatment. Female subjects weighed 3.6 kg (NS) more on average than healthy women, a difference explained by an increase in the body fat of 6.0 kg (P < 0.001) with a simultaneous decrease of 2.4 kg in the extracellular water (P < 0.001). The body cell mass was similar to that seen in the controls.

CONCLUSIONS

Adult patients with growth hormone deficiency have an increased body weight compared to normals of the same age, sex and height, due to an increment of the body fat with a simultaneous reduction in the total body water.

Growth hormone deficiency in 'little' mice results in aberrant body composition, reduced insulin-like growth factor-I and insulin-like growth factor-binding protein-3 (IGFBP-3), but does not affect IGFBP-2, -1 or -4

Although GH is known to regulate somatic growth during development, its role in regulating adult body composition is less well defined. The effects of GH on individual body compartments--water, fat, protein and mineral--are achieved both by the action of GH and by a GH-induced hormone, insulin-like growth factor-I (IGF-I). We used a genetic model of GH deficiency, the 'little' (gene symbol lit) mouse, to determine the GH regulation of IGF-I and its insulin-like growth factor-binding proteins (IGFBPs) and to define the interaction between these hormones and each body compartment in adults. Our results showed that GH-deficient lit/lit mice had reduced levels of serum IGF-I (range 38-130 micrograms/l) compared with normal lit/+ littermates (range 432-567 micrograms/l) between 2 and 52 weeks of age. The lit/lit mice did not experience the fivefold increase in IGF-I between 2 and 4 weeks of age that was seen in lit/+ mice. In lit/lit serum, overall binding of 125I-labelled IGF-I to the four IGFBPs was reduced, solely in response to a reduced amount of IGFBP-3. No overall differences were found between lit/lit and lit/+ mice in the binding of 125I-labelled IGF-I to IGFBP-2, -1 or -4. Age-related declines in IGF-I and IGFBPs were seen in lit/lit mice. However, adult levels of IGF-I were maintained in lit/+ mice to at least 52 weeks of age, as were levels of IGFBP-1 and -4, while IGFBP-3 and -2 declined with age. With respect to body composition, comparison of lit/lit with lit/+ mice showed that the lit/lit mice were characterized by abnormally large adipose tissue stores and reduced body water, protein and mineral from 2 weeks onward. These changes occurred despite normal energy intake in lit/lit mice up to 52 weeks of age, indicating that neither undernutrition nor hyperphagia is characteristic of this GH-induced model of obesity. Furthermore, lit/lit males accrued more body fat beginning at an earlier age than lit/lit females. With advancing age, the per cent body fat increased in both lit/lit and lit/+ mice, while the per cent body water and mineral declined. In lit/lit but not lit/+ mice, per cent protein also declined with age. The changes in body water and fat are attributable to lack of adequate GH in the genetically GH-deficient lit/lit mouse. On the other hand, the changes in body protein are more likely to be effects of IGF-I.(ABSTRACT TRUNCATED AT 400 WORDS)

Long-term serum lipid lowering, behavior modification, and weight loss in obese women

Reduced calorie intake, changes in the composition of foods ingested, and increased physical activity are the usual initial recommended therapies for the obesity that often accompanies hypercholesterolemia and other hyperlipidemias. Collectively resulting in weight loss, these behavioral changes are known to produce short-term (< or = 7- to 9-mo) reductions in serum cholesterol and other lipids. In contrast, previous long-term (> or = 1-yr) investigations fail to disclose a cholesterol-lowering effect of weight loss, although the subjects in these studies were not hypercholesterolemic. The aim of our investigation was to examine the long-term changes in serum lipids that occurred in a representative cohort of healthy obese (n = 45, body mass index mean +/- SD 39.0 +/- 8.6 kg/m2) women after they completed a 15-wk conventional behavior-modification program. The serum cholesterol level of this cohort was elevated at baseline (6.18 +/- 1.41 mM, > or = 75th percentile). At the time of follow-up (17.0 +/- 7.0 mo), there were significant decreases in body weight (-16.7 kg, p < 0.001) and reductions in serum total (-0.53 mM, p < 0.01) and low-density lipoprotein (-0.35 mM, p < 0.05) cholesterol. Serum triglyceride levels also decreased significantly (-0.38 mM, p < 0.001), and serum high-density lipoprotein levels remained unchanged; the ratio of high-density lipoprotein total cholesterol increased significantly (p < 0.05) relative to baseline levels. Multiple stepwise regression analysis indicated that the best predictor of percentage change in each respective lipid was its own baseline level.(ABSTRACT TRUNCATED AT 250 WORDS)

[Current problems in pediatric intensive care from the pathophysiologic viewpoint. I. Changes in body composition and fluid compartments in relation to age]

A sufficient intensive therapy for children requires an age related knowledge of the bodies composition and the connection between each individual part. A summary of the questions of body composition in relation to age and internal comparison size, especially in connection with the bodies surface will be given.

[Characteristics of the menstrual cycle in relation to sex-typical distribution of fatty tissue]

The association between duration as well as regularity of the menstrual cycle and the sex type specific distribution of the subcutaneous fat tissue has been investigated in 327 patients. It turned out that the so-called 'gynecoid' subcutaneous fat distribution was associated with shorter and more regular menstrual cycles. A marked relationship between the sex type specific fat distribution and the bleeding duration could not found.

Effect of smoking on maternal glucose metabolism

Maternal smoking, studied in late pregnancy, was found to be associated with lower blood glucose values, both during fasting and after an intravenous glucose load. As a correlation between blood glucose levels and infant birth weight has been reported, it is possible that smoking during pregnancy might reduce fetal growth through an effect on maternal glucose metabolism.

Humoral mediation of changing body composition during aging and chronic inflammation

A decline in lean body mass and an accompanying increase in fat mass are known to occur during aging. The consequences of these changes in body composition may include decreased strength and physical activity, altered energy metabolism, and impaired resistance to infection. The mechanisms behind these age-related events remain unknown, but they may include changes in some of the hormonal and cytokine mediators that seem to regulate body composition. The common inflammatory condition rheumatoid arthritis could provide a useful model of these phenomena dissociated from chronological aging. This article reviews changes in neuroendocrine and immune modulators of metabolism and their consequences during aging and chronic inflammation.

Young and old subjects matched for aerobic capacity have similar noradrenergic responses to exercise

Sympathetic nervous system activity as indicated by circulating norepinephrine has been demonstrated to increase with advancing chronological age both at rest and during submaximal exercise. Much of the earlier work investigating this aging phenomenon used a younger group that had a higher peak oxygen consumption (VO2) than did the older group, which made comparisons difficult. In the present study, young [n = 7, 36 +/- 1.0 (SE) yr] and old subjects (n = 8, 61 +/- 1.2 yr) were matched on peak VO2 and then exercised at approximately the same relative submaximal VO2 (75%) and power output on a cycle ergometer for 21 min. Blood samples were collected at rest and in the 7th, 14th, and last minute of a 21-min exercise bout via an indwelling catheter in an antecubital vein. The norepinephrine responses for the young and old groups, respectively, were as follows: rest, 486 +/- 111 vs. 673 +/- 108; 7 min, 1,258 +/- 255 vs. 1,185 +/- 172; 14 min, 1,639 +/- 316 vs. 1,528 +/- 288; and 21 min, 2,038 +/- 488 vs. 1,936 +/- 453 pg/ml. These responses were not significantly different between the groups at any time period. The epinephrine values for the age groups were not statistically different: rest, 115 +/- 60 vs 88 +/- 51; 7 min, 140 +/- 18 vs. 326 +/- 88; 14 min, 216 +/- 33 vs. 366 +/- 104; and 21 min, 324 +/- 100 vs. 447 +/- 113 pg/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypophagic rats with dorsomedial hypothalamic lesions produce lighter and smaller pups with a lower survival rate at weaning than offspring of sham-operated controls

Weanling and mature rats with dorsomedial hypothalamic nucleus lesions (DMNL rats) show reduced ponderal and linear growth and hypophagia and hypodipsia in the presence of normal body composition and anabolic hormone levels. The present study was conducted to assess their reproductive/parenting capacity and some offspring parameters. Four groups were used: DMNL mothers and fathers, DMNL mothers and control (SCON) fathers, SCON mothers and DMNL fathers, and SCON mothers and SCON fathers. The constituent rats of each group were bred to yield between 14 and 22 litters. The smallest litter size, litter weight, mean pup weight, percent of live-born and percent of weaned pups and greatest percentage of still-born pups were recorded when both parents were DMNL rats. The latter parents also cannibalized the majority of litters. The above parameters improved when only one parent was a DMNL rat, but this was still significantly below the offspring of SCON x SCON parents. The DMN is not part of the classical hypophysiotropic area (HTA), but earlier findings indicate hyperprolactinemia in DMNL rats. Therefore, the lesion-induced hypophagia during gestation and the postpartum neuroendocrine profile of the DMNL mothers may be the cause of the observed litter deficiencies and poor survival.

Analysis of performance of prepubertal swimmers assessed from anthropometric and bio-energetic characteristics

The relationship between anthropometric and bio-energetic data and timed performance over 50 to 400 m was studied in 25 young male swimmers [11.3 (SD 1) years]. Anthropometric measurements included height, body mass, body fat mass, body area, thoracic section area (Ats) thoracic circumferences, lengths of upper limb, bi-acromial and bi-iliac diameters. Maximal oxygen consumption (VO2max; direct method), maximal anaerobic power (W(an),max; force-velocity test) and mean power in 30 s sprint (W30 s; Wingate test) were also measured. Each of these bio-energetic variables was expressed in absolute terms, relating to body mass, body area and Ats. The stepwise regression method was used to determine contribution of the variables (anthropometric and/or bio-energetic) of the time achieved over the distance. The W30 s/Ats accounted for 46% of the time over 50 m (negative correlation). The VO2max/Ats and height were negatively correlated with the times of performances over 100 m, 200 m and 400 m, these two variables accounted for 71% to 77% of the performance. These results would indicate that even in young boys, anthropometric and bio-energetic characteristics are both important in swimming performance, particularly the bio-energetic variables expressed per Ats.

Two classes of mammalian skeletal muscle fibers distinguished by metabolite content

Phosphorus NMR spectroscopy and HPLC analyses were made on isolated rat and mouse muscles selected for different volume fractions of the major known fiber types. We tested the hypothesis that muscle cell types at rest have intrinsically different contents of PCr, ATP and Pi. The Pi content was low and the PCr and ATP contents were high in muscles with large contents of type 2b and 2a fibers, and vice versa in muscles with large volume fraction of types 1 and 2x fibers. From the profile of these metabolites we could distinguish only two classes of fibers in the murine muscles and predict well the composition of cat muscles. For the first class, types 2a and 2b fibers, the intracellular concentrations were: ATP 8 mM; total Cr 39 mM; PCr 32 mM; Pi 0.8 mM; ADP 8 microM. For the second class, type 1 and 2x fibers, these quantities are: ATP 5 mM; TCr 23 mM; PCr 16 mM; Pi 6 mM; ADP 11 microM. Thus our results establish a new and apparently general criterion upon which to distinguish skeletal muscle cells, one based on the resting content of bioenergetically important metabolites.

Reduction of body mass and change in body composition on a very low calorie diet

The quality of weight loss was estimated during a very low calorie diet (VLCD) weight-reducing regime by determining the body composition every second week using near-infra-red interactance (NII). The study was performed on 127 overweight volunteers, aged 18-72 years, who, for eight consecutive weeks, used a VLCD to lose weight. Mean weight reduction was 12.7 kg (12.6% of initial weight). Mean body fat (BF) loss was 9.5 kg (23.8% of initial BF), which constitutes 75% of the weight loss. Mean reduction in lean body mass (LBM) was 3.2 kg (5.2% of initial LBM). We found no correlation between initial body mass index (BMI) and loss of LBM, or between initial body composition and weight loss. Weight reduction observed in this study is mainly due to reduction in body fat, and the loss of LBM is considered not to be larger than acceptable.

Effect of inpatient versus outpatient measurement protocol on resting metabolic rate and respiratory exchange ratio

Resting metabolic rate (RMR) and respiratory exchange ratio (RER) were measured, using indirect calorimetry, in 9 healthy, male subjects (28.6 +/- 3.3 years) under three conditions: (1) an inpatient, meal-controlled protocol (IPM) in which subjects were fed an evening meal and slept overnight in the laboratory prior to the morning test; (2) an outpatient, meal-controlled protocol (OPM) in which subjects were fed the same meal but slept at home prior to being transported to the laboratory for testing, and (3) and outpatient protocol (OP) in which meal was not controlled, but subjects were instructed to fast for 12 h prior to testing. There were no statistically significant differences in RMR between protocols (IPM = 7,928 +/- 360, OPM = 8,015 +/- 331 and OP = 7,987 +/- 315 kJ/day) or in fasting RER (IPM = 0.82 +/- 0.01, OPM = 0.82 +/- 0.02 and OP = 0.81 +/- 0.02). These data indicate that in young, healthy males RMR and RER are similar when measured under inpatient or outpatient conditions.

Protein absorption and energy digestibility at high altitude

To test the hypothesis that malabsorption of dietary protein is partly responsible for the weight loss observed during prolonged altitude exposure, six healthy male subjects [31.8 +/- 4.5 (SD) yr] received 15N-labeled soya protein by mouth and [15N]glycine intravenously at 122 and 5,000 m. From the subsequent 4-day total urine and fecal pools, the different fractions of the administered 15N were determined by mass spectrometry. Weight and skinfold thickness were measured at the beginning and end of the altitude exposure. In addition, the overall digestible energy of the diet at altitude was assessed by a 3-day diet control and adiabatic bomb calorimetric assessment of the energy content of the corresponding fecal pool. The average decrease of the subjects' weight during altitude exposure was 3%. Loss of fat mass at altitude estimated from the skinfold measurements was 9%. Protein absorption, calculated as 100--[fecal excretion of 15N after ingestion of 15N soya protein (% of dose given)--fecal excretion of 15N after injection of 15N glycine (% of dose given)], was not significantly impaired at altitude compared with sea level (96 vs. 97%, respectively), and overall digestible energy at altitude, calculated as 100--percent undigested gross energy in the feces, amounted to 96%. It is concluded that, at least up to an altitude of 5,000 m, malabsorption does not play a role in altitude-related weight loss.

Cardiovascular responses to lower body negative pressure in trained and untrained older men

To determine whether aerobic conditioning alters the orthostatic responses of older subjects, cardiovascular performance was monitored during graded lower body negative pressure in nine highly trained male senior athletes (A) aged 59-73 yr [maximum O2 uptake (VO2 max) = 52.4 +/- 1.7 ml.kg-1 x min-1] and nine age-matched control subjects (C) (VO2 max = 31.0 +/- 2.9 ml.kg-1 x min-1). Cardiac volumes were determined from gated blood pool scintigrams by use of 99mTc-labeled erythrocytes. During lower body negative pressure (0 to -50 mmHg), left ventricular end-diastolic and end-systolic volume indexes and stroke volume index decreased in both groups while heart rate increased. The decreases in cardiac volumes and mean arterial pressure and the increase in heart rate between 0 and -50 mmHg were significantly less in A than in C. For example, end-diastolic volume index decreased by 32 +/- 4 ml in C vs. 14 +/- 2 ml in A (P < 0.01), mean arterial pressure declined 7 +/- 5 mmHg in C and increased by 5 +/- 3 mmHg in A (P < 0.05), and heart rate increased 13 +/- 3 beats/min in C and 7 +/- 1 beats/min in A (P < 0.05). These data suggest that increased VO2 max among older men is associated with improved orthostatic responses.

Principal alterations to drug kinetics and dynamics in the elderly

People over the age of 64 constitute 15% of the population in the UK, yet they consume approximately 30% of all National Health Service drug prescriptions, and adverse drug reactions account for 10.4% of all admissions to geriatric medical assessment wards. Many published studies concerning the pharmacology of old age are seriously flawed. Problems include failure to measure the drug bio-availability and the selection of subjects with overt or sub-clinical disease. It is difficult to make general rules about the effect of ageing on drug kinetics and dynamics. Each drug has to be tested separately.

Relationship between psychosocial functioning and body fat in preschool children: a longitudinal investigation

This study examined whether preschool children differed on measures of psychosocial functioning both cross-sectionally and longitudinally. One hundred and thirty-two children who varied in levels of body fat participated in the study along with their natural parents. Results indicated that the children did not differ in levels of self-esteem and family functioning as a function of their body fat. Prospectively, physical self-esteem weakly (but significantly) correlated with body fat at 1 and 2 years, and father's perception of family functioning predicted body fat at 1 year only. Results suggested that childhood obesity may not develop as a result of psychosocial factors.

Energy expenditure climbing Mt. Everest

Weight loss is a well-known phenomenon at high altitude. It is not clear whether the negative energy balance is due to anorexia only or an increased energy expenditure as well. The objective of this study was to gain insight into this matter by measuring simultaneously energy intake, energy expenditure, and body composition during an expedition to Mt. Everest. Subjects were two women and three men between 31 and 42 yr of age. Two subjects were observed during preparation at high altitude, including a 4-day stay in the Alps (4,260 m), and subsequently during four daytime stays in a hypobaric chamber (5,600-7,000 m). Observations at high altitude on Mt. Everest covered a 7- to 10-day interval just before the summit was reached in three subjects and included the summit (8,872 m) in a fourth. Energy intake (EI) was measured with a dietary record, average daily metabolic rate (ADMR) with doubly labeled water, and resting metabolic rate (RMR) with respiratory gas analysis. Body composition was measured before and after the interval from body mass, skinfold thickness, and total body water. Subjects were in negative energy balance (-5.7 +/- 1.9 MJ/day) in both situations, during the preparation in the Alps and on Mt. Everest. The loss of fat mass over the observation intervals was 1.4 +/- 0.7 kg, on average two-thirds of the weight loss (2.2 +/- 1.5 kg), and was significantly correlated with the energy deficit (r = 0.84, P < 0.05). EI on Mt. Everest was 9-13% lower than during the preparation in the Alps.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential in vivo measurements of body composition of calves exposed to natural infection with gastrointestinal nematodes

Sequential in vivo measurements of total body water, exchangeable sodium and exchangeable potassium, made by radioisotopic dilution techniques, were used to determine changes in body composition in calves exposed to natural infections with gastrointestinal nematodes during their first grazing season. Two groups of calves were studied, one of which received a sustained release anthelmintic bolus at turn out. Over the grazing season the bolus-treated calves showed a significantly improved pattern of bodyweight gain, compared with the untreated control calves. There were also significant increases in both total body water and exchangeable potassium, as a percentage of the bodyweight, in the bolus calves compared with the controls. These findings indicated that body protein as a percentage of bodyweight was increased in the bolus animals. The bolus-treated calves also had significantly lower serum pepsinogen concentrations, faecal egg counts and worm burdens.

Novel myosin isoform in nuclear chain fibers of rat muscle spindles produced in response to endurance swimming

With the use of myosin adenosinetriphosphatase (ATPase) and immunofluorescence staining methods, the adaptive responses of intrafusal and extrafusal fibers to endurance swimming were studied in frozen sections of rat soleus (SOL) and extensor digitorum longus (EDL) muscles. Glycogen depletion confirmed muscle fatigue at the end of a standardized bout of exercise. No significant age-dependent changes in myosin isoforms were detected in any fibers. The 12-wk training increased type I fibers by 10.9% in the SOL and type IIa fibers in the EDL by 16.6%. In trained muscle sections, both staining methods identified a permuted chain fiber, expressed the same as the myosin isoform in the bag2 fiber. However, no exercise-induced change of myosin isoform profile was found in the bag1 and bag2 fibers. Myosin ATPase (and immunofluorescence) staining showed the percentage of permuted chain fibers increased from 0 to 6.7% (5.6%) after 6 wk of training and to 19.2% (14.1%) after 12 wk of training and that it was still at 6.1% (4.2%) 10 wks after training. A novel myosin isoform may thus be expressed in nuclear chain fibers by repetitive recruitment of muscle spindles.

The effects of varying protein and energy intakes on the growth and body composition of pigs. 1. The effects of energy intake at constant, high protein intake

The objective of the present experiment was to define the form of the relationship between varying levels of energy intake at constant, high protein intake and the performance of young pigs. By doing so it was expected that we could distinguish between four models that predict the pig's responses to its diet as rates of protein and lipid retention. Forty young pigs were assigned at 12 kg live weight either to an initial slaughter group (n 8) or to one of four allowances of starch intake at a constant intake of a high-protein feed (with 345 g crude protein (nitrogen x 6.25)/kg food). Half the pigs were killed after 4 weeks and half after 8 weeks on the treatments; at each slaughter point on each treatment half the pigs were entire males and half were females. Increasing the intake of starch (energy) resulted in significant increases in the rates of live weight, empty-body, protein and lipid gains of pigs slaughtered at both stages. There was no minimum positive lipid:protein ratio in the gain of the pigs. Male pigs deposited more protein and less lipid than females but this effect of sex on protein and lipid retention was seen only on the two highest allowances of starch intake. The calculated efficiency of protein utilization increased with increasing starch intake up to a maximum of 0.81, when probably the energy:protein in the diet became non-limiting. The results led to the rejection of two of the models that predict the rates of protein and lipid retention as responses to protein and energy intake, but the two remaining models could not be rejected, at least qualitatively.

Energy supplementation reverses changes in the basal metabolic rates of chronically undernourished individuals

The objective of the present study was to examine the influence of energy supplementation and its cessation thereafter on the basal metabolic rates (BMR) of chronically undernourished individuals. Seven apparently healthy males were supplemented daily with 3.35 MJ (15 g protein, 35 g fat, 105 g carbohydrate) for 12 weeks. The average gain in body-weight was 1.9 kg (body fat, 58%; fat-free mass (FFM), 42%). The rise in BMR exceeded that accounted for by the increases in FFM during the 12 weeks of supplementation and was attributed to increases in the amount and activity of the visceral tissue as well as to an added cost of lipogenesis. At 12 weeks after cessation of the supplement, body-weights and FFM had decreased to presupplementation levels. BMR at this stage were significantly lower than at the 12th week of supplementation, when expressed per kg FFM or when adjusted for FFM using an analysis of covariance. These results suggest an increase in the metabolic efficiency during this negative energy balance period. The study demonstrates that, in the chronically undernourished, the changes in BMR are reversible and, hence, physiologically important to the process of adaptation to low-energy intakes.

Body composition and bone mass in post-menopausal women

OBJECTIVE

We aimed to assess total body composition and to study the interrelationships between fat and lean tissue mass with total and regional bone mass in healthy British post-menopausal women.

DESIGN AND PATIENTS

Total body composition and regional bone mass were measured in 97 healthy post-menopausal women recruited from the general community. The mean age was 57.9 years, range 49-65.

MEASUREMENTS

Total body composition (fat, lean tissue and bone mineral) and regional bone density in the lumbar spine and femur were measured by dual energy X-ray absorptiometry on a Lunar DPX.

RESULTS

Significant negative correlations with age were found for total body bone mineral density (r = -0.200, P = 0.049), and lumbar spine bone mineral density (r = -0.28, P = 0.006); the calculated rate of bone loss from these two sites was 0.33 and 0.7% per annum respectively. Fat tissue mass showed a positive correlation with age (r = 0.22, P = 0.03). High correlations were observed between total body and regional bone mineral density (r = 0.755-0.829, P < 0.001). After adjustment for age and lean mass, statistically significant correlations were seen between fat tissue mass and all bone mass measurements (P < 0.01-0.001), the strongest correlations being found for total body bone mineral content and density (r = 0.477 and 0.488 respectively). Lean tissue mass showed a strong correlation with total body bone mineral content (r = 0.580, P < 0.001), after adjustment for age and fat mass; it was less strongly correlated with other bone mass measurements than fat mass, showing only weak correlations with total body, trochanteric and lumbar spine bone mineral density (r = 0.228-0.246, P < 0.05). Age-adjusted body weight showed stronger correlations with total and regional bone mass than did either body mass index or height.

CONCLUSIONS

Both fat and lean tissue mass are related to total and regional bone mass in post-menopausal women, the relationship being strongest for fat mass. Body weight shows stronger correlations with bone mass than either height or body mass index. In view of the direction and magnitude of changes in fat, lean tissue and bone mineral after the menopause, adiposity and muscularity are more likely to be determinants of peak bone mass than of the rate of post-menopausal bone loss.

Evaluation of protein requirements for trained strength athletes

Leucine kinetic and nitrogen balance (NBAL) methods were used to determine the dietary protein requirements of strength athletes (SA) compared with sedentary subjects (S). Individual subjects were randomly assigned to one of three protein intakes: low protein (LP) = 0.86 g protein.kg-1.day-1, moderate protein (MP) = 1.40 g protein.kg-1.day-1, or high protein (HP) = 2.40 g protein.kg-1.day-1 for 13 days for each dietary treatment. NBAL was measured and whole body protein synthesis (WBPS) and leucine oxidation were determined from L-[1-13C]leucine turnover. NBAL data were used to determine that the protein intake for zero NBAL for S was 0.69 g.kg-1.day-1 and for SA was 1.41 g.kg-1.day-1. A suggested recommended intake for S was 0.89 g.kg-1.day-1 and for SA was 1.76 g.kg-1.day-1. For SA, the LP diet did not provide adequate protein and resulted in an accommodated state (decreased WBPS vs. MP and HP), and the MP diet resulted in a state of adaptation [increase in WBPS (vs. LP) and no change in leucine oxidation (vs. LP)]. The HP diet did not result in increased WBPS compared with the MP diet, but leucine oxidation did increase significantly, indicating a nutrient overload. For S the LP diet provided adequate protein, and increasing protein intake did not increase WBPS. On the HP diet leucine oxidation increased for S. These results indicated that the MP and HP diets were nutrient overloads for S. There were no effects of varying protein intake on indexes of lean body mass (creatinine excretion, body density) for either group. In summary, protein requirements for athletes performing strength training are greater than for sedentary individuals and are above current Canadian and US recommended daily protein intake requirements for young healthy males.

The effects of varying protein and energy intakes on the growth and body composition of pigs. 2. The effects of varying both energy and protein intake

The objective of the experiment was to define the form of the relationship between varying levels of protein and energy intake and the performance of young pigs. Forty-four young-pigs were assigned at 12 kg live weight for 6 weeks either to an initial slaughter group (n 8) or to one of the nine feeding treatments (n 4); three allowances of a high-protein food with 355 g crude protein (nitrogen x 6.25; CP)/kg (P1, P2, P3) at three levels of feeding (L, M and H). Each feeding level was met by supplementing the allowance of feed P with the appropriate amount of starch and each treatment had two males and two females. The rate of protein deposition was not affected by feeding level at the two lowest allowances of basal feed P (P1 and P2), but it increased with increasing the feeding level for the pigs on treatment P3. Males deposited more protein than females, but this effect was more pronounced with treatment P3. The rate of lipid deposition increased with each increase in the level of feeding and decreased with increasing the allowance of feed P. The calculated efficiency of protein utilization (ep) was expressed as a function of the energy:protein ratio in the feed (MJ metabolizable energy/kg digestible CP). The best model to describe the relationship was a linear-plateau model, with the maximum value for ep of 0.814 at 73 MJ/kg. This relationship provided the basis of a model that could predict the response of a growing pig to its diet as rates of protein and lipid retention.

The haemodynamics of obesity: a theoretical analysis

BACKGROUND

Obesity and hypertension are frequently associated with one another, and changes in body weight are usually accompanied by consensual changes in blood pressure.

OBJECTIVE

To examine formally the haemodynamic conditions required for a weight gain to cause a rise in blood pressure in the resting state.

METHODS

The relevant equations were developed, and then used in a simulation to predict blood pressure and peripheral vascular resistance in response to changes in body weight. The model was tested on data taken from published reports. Furthermore, the impact of the composition of the excess weight, i.e. fat versus muscle tissue, on the haemodynamics of obesity was incorporated into the simulation by using a range of tissue-specific blood flow rates taken from published reports.

RESULTS

The key determinant of weight-induced increases in blood pressure is a disproportional increase in cardiac output, which is not fully accounted for by the haemodynamic contribution of new tissues. An increase in muscle tissue relative to fat in newly gained weight is a further factor in the blood pressure increase arising from any given level of excess weight.

CONCLUSIONS

The disproportional increase in cardiac output in obesity is best attributed to stimulation of cardiac dynamics by the adrenergic nervous system. The low resistance of adipose tissue relative to muscle may be the physiologic basis for the dominance of fat-free mass in multiple regression analyses of blood pressure determinants in the population; it further suggests that in the obese hypertensive, fat tissue may provide protection against cardiovascular disease by limiting increases in total peripheral resistance.

Effect of very low calorie diet on body composition and exercise response in sedentary women

The effect of very low calorie diet (VLCD) on fat-free mass (FFM) and physiological response to exercise is a topic of current interest. Ten moderately obese women (aged 23-57 years) received VLCD (1695 kJ.day-1) for 6 weeks. FFM, estimated by four conventional techniques, and heart rate (fc), blood lactate (la(b)), mean arterial pressure (MAP), respiratory exchange ratio (R) and rating of perceived exertion (RPE) were measured during a submaximal cycle ergometry test 1 week before, in the 2nd and 6th week, and 1 week after VLCD treatment. Strength and muscular endurance of the quadriceps and hamstrings were tested by isokinetic dynamometry. The 11.5-kg reduction in body mass was approximately 63% fat and 37% FFM. The latter was attributed largely to the loss of water associated with glycogen. Whilst exercise fc increased by 9-14 beats.min-1 (P < 0.01), there were substantial decreases (P < 0.01) in submaximal MAP (1.07-1.73 kPa), la(b) (0.75-1.00 mmol.l-1 and R (0.07-0.09) during VLCD. R and fc returned to normal levels after VLCD. Gross strength decreased (P < 0.01) by 9 and 13% at 1.05 rad.s-1 and 3.14 rad.s-1, respectively. Strength expressed relative to body mass (Nm.kg-1) increased (P < 0.01) at the lower contraction velocity, but there was no change at the faster velocity. Muscular endurance also decreased (P < 0.01) by 62 and 82% for the hamstrings and quadriceps, respectively. We concluded that the strength decrease was a natural adaptation to the reduction in body mass as the ratio of strength to FFM was maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of early undernutrition in rats on their body fat and RNA content in VMH neurons

The RNA content of the ventromedial hypothalamus (VMH) and lateral hypothalamic area (LHA) neurons, and the epididymal, retroperitoneal, and liver fat content of 150-day-old male rats submitted to neonatal undernutrition, were investigated. The neonatal undernutrition was carried out by two different ways. First, by reducing the litters to two pups per nest from birth to weaning. The pups from normal litters (eight pups/nest) served as controls. Secondly, by separating half of the pups (four pups) from normal litters for 8 h daily during the first 5 postnatal days. The remaining nonseparated pups served as their controls. The data show that both groups of early undernourished pups had a significantly increased RNA content in the VMH neurons (RNA content in the LHA neurons was unchanged) and a significantly decreased epididymal, retroperitoneal, and liver fat content in comparison with their controls. The results indicate that early undernutrition leads to a permanent increase in the functional activity of VMH and alteration in fat metabolism in rats.

Composition of weight loss in severely obese women: a new look at old methods

Seven severely obese, outpatient dieters lost weight (mean +/- SEM, 14 +/- 1 kg), and the composition of weight lost was determined by six different models. Total body water (TBW), total body potassium (TBK), and body density, bone mineral content, and fat as determined by dual photon absorptiometry (DPA) were measured while subjects were weight-stable, before and after weight loss. Fat loss was calculated by three two-compartment models (2C-TBW, 2C-TBK, and hydrodensitometry [2C-HD]), one three-compartment model (HD with correction for water content of fat-free mass [FFM], 3C), and one four-compartment model (HD with correction for water and mineral content of FFM, 4C), and was measured directly by DPA. Mean composition of weight loss was similar for all models (mean weight lost as fat: 89% for DPA, 91.5% for 4C, 89% for 3C, 88.6% for 2C-HD, and 87% for 2C-TBW) except 2C-TBK (weight lost as fat, 66%). There was a much wider range of individual values for the 2C-TBW and 2C-TBK models (17% to 138% and 18% to 93%, respectively) than for the multicompartment models (63% to 112%) and DPA (76% to 107%). Almost opposite results were obtained for the same individual when using the 2C-TBK and 2C-TBW models. The discrepancy between these models was due to the inverse relationship between changes in TBW and TBK in the group as a whole (r = -.34, NS). In addition, TBK loss was found to be dependent on the initial level of hyperinsulinemia, calculated as the area under the 2-hour oral glucose tolerance curve.(ABSTRACT TRUNCATED AT 250 WORDS)

Rheumatoid cachexia: depletion of lean body mass in rheumatoid arthritis. Possible association with tumor necrosis factor

OBJECTIVE

To investigate body composition and serum tumor necrosis factor (TNF) levels in a series of 24 patients with rheumatoid arthritis (RA).

METHODS

Body composition assessment by anthropometric measures and bioelectrical impedance. Cytokine determination in serum by ELISA:

RESULTS

When compared to United States population norms, 16 of the subjects (67%) were cachectic. In regression models, lean body mass (LBM) was inversely associated with the number of swollen joints (p < 0.025). Elevated TNF-alpha was found in 3 of 5 flaring patients vs 0 of 18 patients with less active disease (p = 0.001). These 3 were all cachectic, while the 2 flaring patients without detectable TNF had normal LBM (p < 0.03). Among the whole group, there was a trend toward increasing disability with decreased LBM after adjusting for joint pain and disease duration (p < 0.07).

CONCLUSION

Cachexia is common in RA, and may be cytokine driven. Given the prognostic impact of LBM wasting in other diseases, the effect of rheumatoid cachexia on outcome in RA deserves further study.

Acute alcohol intoxication, body composition, and pharmacokinetics

The present study compared alcohol pharmacokinetics associated with body weight, anthropometrically estimated total body water, and body mass index in men and women in two experimental sessions, single dose and double dose. All subjects were given the same amount of alcohol (2.3 and 4.6 oz. 86 proof vodka for single dose and double dose, respectively). Data analyses found a significant correlation between body mass index and peak blood alcohol concentration (BAC). Weight and total body water were not significantly correlated with peak BAC. The findings suggested that body mass index may be considered a better criterion than body weight for equating alcohol doses.

The metabolic output of avian (Sturnus vulgaris, Calidris alpina) adipose tissue liver and skeletal muscle: Implications for BMR/body mass relationships

1. The oxygen uptake rate of avian adipose tissue, liver and skeletal muscle slices were measured. 2. The energy consumption of fat was less than one tenth that of liver and muscle. 3. Thus, interspecific allometric equations for the prediction of basal metabolic rate from body mass will not be accurate throughout the avian annual cycle unless changes in body composition are taken into account.

Role of body fat distribution in the decline in insulin sensitivity and glucose tolerance with age

The relationships of body composition and physical fitness [maximal aerobic capacity (VO2max)] to the decline in insulin sensitivity with age were examined in healthy older (47-73 yr; n = 36) and young (19-36 yr; n = 13) men. In 18 older men with normal glucose tolerance (OGTT), glucose disposal rates (M) during hyperinsulinemic euglycemic clamps correlated negatively with the waist to hip ratio (WHR; r = -0.77; P < .001) and percent body fat (r = -0.46; P < 0.05) and positively with VO2max (r = 0.54; P < 0.05), but not with age. Similar relationships existed in the 36 older men with a spectrum of OGTT responses; however, only WHR was independently related to M (r2 = 0.32; P < 0.01). In the older men with normal OGTT, M (mean +/- SEM, 7.88 +/- 0.43 mg/kg fat-free mass.min) was not different from that in the young men (8.56 +/- 0.47; P = NS). Furthermore, in older and young men with normal OGTT matched for WHR, percent fat, or VO2max, glucose disposal was comparable at sequential 15-min intervals during the clamp and in its relationship to insulin concentrations at the tissue level (multicompartmental analysis). In contrast, despite higher steady state plasma insulin levels during the clamp, M was significantly lower in the older men with a higher WHR, greater percent fat, lower VO2max, or impaired OGTT. Thus, in healthy older men up to the age of 73 yr, insulin sensitivity and glucose tolerance are affected primarily by the regional body fat distribution, not age, obesity, or VO2max.

[Percentage of body fat and risk factors of coronary heart disease]

This study is a cross sectional analysis using measurement of the relative amount of fat on the right upper arm by means of the near infra-red method (NIR) and computerised calculation of the percent body fat by the use of the Futrex 5000. The total sample consisted of 1,988 subjects (942 women and 1,046 men) in the two age groups 40-42 years (n = 1,180) and 65-67 years (n = 808). Average percentage of relative fat in the total sample was 26.7, average percentage of body fat was 26.5 and average Body Mass Index, BMI (kg/m2) was 24.4. The percentage of fat and the BMI would both appear to increase with age and be higher in non-smokers. The BMI was higher in men, while the percentage of body fat was higher in women. A relatively weak correlation was found between the relative amount of fat and the BMI (0.4 < or = r < or = 0.57) but there was a relatively strong correlation between the percentage of fat and the BMI (0.72 < or = r < or = 0.88). The correlation with total cholesterol, triglycerides, blood pressure (SBP, DBP, MAP) and susceptibility to cardiac infarction (calculated estimated units) was similar for both the percentage of fat and the BMI. All correlations were positive, but with a relatively low r (0.05 < or = r < or = 0.39). The interaction between the percentage of body fat and the BMI would appear to be independent of age and sex.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of endurance training on energy intake, norepinephrine kinetics, and metabolic rate in older individuals

The role of physical activity in the regulation of energy intake in older persons is presently unclear. We therefore examined the influence of endurance training on voluntary energy intake and the associated changes in resting metabolic rate (RMR) and norepinephrine (NE) kinetics in seven healthy (six men, one woman) older individuals (69.4 +/- 2.2 years) under supervised living conditions. Energy intake was measured by covert assessment in a clinical research environment during: (1) a 10-day inpatient control period (no exercise); (2) a 10-day light exercise period (150 kcal per session, 3 times/wk); and (3) a 10-day moderate exercise period (300 kcal per session, 3 times/wk). RMR was determined after all three periods, and NE kinetics were assessed before and after training by infusions of tritiated NE ([3H]-NE). No significant change in energy intake was found between the control (2,378 +/- 130 kcal/d) and light exercise (2,449 +/- 104 kcal/d) periods, whereas energy intake increased 17% (P less than .01) during moderate exercise (2,785 +/- 161 kcal/d). Changes in RMR paralleled those of energy intake, as no differences were noted in RMR after control (1.03 +/- 0.12 kcal/min) and light exercise periods (1.04 +/- 0.12 kcal/min), but RMR increased 9% (1.13 +/- 0.14 kcal/min, P less than .01) after moderate endurance training, despite no changes in body composition.(ABSTRACT TRUNCATED AT 250 WORDS)

Skinfolds and body composition of sports participants

Body composition of 1815 North-Italian young sports participants in relation to sex, age, sport and level of performance was investigated. About thickness and anatomical distribution of subcutaneous fat females showed skinfolds thicker than males. Significant differences were observed in skinfold thicknesses means of different sport-groups. Subscapular and forearm skinfolds were the best discriminant variables for males and females respectively. Body density was estimated according to Katch and McArdle (1973) and Durnin and Womersley (1974) equations. Males showed higher body density and lower fat percentage values than females. The lowest value of body density and the highest fat percentage were in male martial art competitors and in females practising skating and athletics. The highest values of body density and the lowest of fat percentage were in males practising athletics and rowing and in female martial art competitors. Highest and lowest values of fat-free mass were in games players and in soccer players and gymnasts respectively. "High aptitude" subjects showed higher fat-free mass values than "middle aptitude" group, besides a tendency towards higher body density values and lower fat percentage than "middle aptitude" group. With aging body density decreased whereas fat percentage and fat-free mass increased.

Basal metabolic rate in adults with growth hormone deficiency and in patients with acromegaly: relationship with lean body mass, plasma insulin level and leucocyte sodium pump activity

1. The relationship of lean body mass, plasma insulin concentration and leucocyte active sodium transport with basal metabolic rate was investigated in 24 adults with growth hormone deficiency before and after treatment with recombinant human growth hormone and in 10 patients with untreated acromegaly. 2. Based on total-body potassium determined by whole-body 40K counting, patients with acromegaly had increased lean body mass, whereas lack of growth hormone was associated with decreased lean body mass. 3. By indirect calorimetry, patients with acromegaly had increased basal metabolic rates and patients with growth hormone deficiency had decreased values when expressed as percentages of values predicted from the WHO/FAO/UNU equations. Basal metabolic rate expressed in terms of lean body mass was similar in acromegaly and growth hormone deficiency, but was higher than normal in both patient groups. 4. The leucocyte ouabain-sensitive sodium efflux rate constant was decreased in both patients with acromegaly and patients with growth hormone deficiency, and there was no correlation with basal energy expenditure, fasting plasma insulin level or serum growth hormone level. 5. There was no increase in the sodium efflux rate constant in patients with growth hormone deficiency after 1 month on treatment with recombinant human growth hormone. 6. Apparent differences in basal metabolic rate in growth hormone deficiency and acromegaly are due to changes in lean body mass. Both adults with growth hormone deficiency and patients with acromegaly have increased energy expenditure, probably owing to changes in fuel metabolism which are not reflected in the leucocyte sodium pump activity.

Moderate exercise in young female S5B/P1 rats does not reduce body fat

Weanling S5B/P1 female rats were divided into four groups as follows: high fat diet, exercised (FE); high fat diet, unexercised (FU); high carbohydrate diet, exercised (CE); and high carbohydrate diet, unexercised (CU). After 25 days of progressive training, exercised rats ran on a motor-driven treadmill for 30 days at 25 m/min per 1 h at 0 degree grade for 6 days a week. Rats were weighed weekly throughout the experiment and food intakes were recorded for the last 3 weeks of the experiment. After euthanasia at 15 weeks of age, three muscles, liver, heart, kidney, 3 fat depots, and tibia-fibula were dissected out and weighted. The carcass, including weighted organs and fat depots, was analyzed for body fat. Exercised rats, regardless of diet, weighed slightly but significantly more than unexercised rats. They also tended to eat more food and to have a higher quantity of fat-free body mass than unexercised rats. Percent body fat was similar for exercised and unexercised rats. The tibia weighed significantly more (p less than 0.05) in CU than in FU rats but the weight was similar in CE and FE rats. The density of the tibia was significantly higher (p less than 0.01) in exercised than in unexercised rats.

Massive overfeeding and energy balance in men: the Guru Walla model

To determine the magnitude of the thermogenic response to a massive long-term overfeeding, an energy-balance study was carried out in nine lean, young Cameroonian men participating in a traditional fattening session: the Guru Walla. Food intake, body weight, body composition, activity, and metabolic rates were recorded during a 10-d baseline period and over the 61-65 d of fattening. Total energy expenditure (TEE) was measured by using doubly labeled water during the baseline period and the final 10 d of Guru Walla. Cumulative overfeeding consisted of 955 +/- 252 MJ (chi +/- SD) mainly as carbohydrate. Body-weight increase was 17 +/- 4 kg, 64-75% as fat. Metabolic rates increased but TEE did not. However, when accounting for the reduction in physical activity, substantial thermogenesis was observed but its amplitude was not greater than that observed under less extreme carbohydrate-overfeeding conditions. If luxuskonsumption does exist, it is not related to the magnitude of the cumulative overfeeding.