Differences In Basal Metabolic Rate Research Articles

Basal metabolic rate and energy costs at rest and during exercise in rural- and urban-dwelling Papua New Guinea highlanders.

(1) To evaluate inter-individual variations, regional and sex differences in the basal metabolic rate (BMR) and related variables; (2) to compare measured BMR with estimated BMR using predictive equations; and (3) to examine the net mechanical efficiency (NME) in step tests. BMR and energy costs at rest and during step tests were measured by the Douglas bag technique of indirect calorimetry. NME was calculated from BMR and energy costs of step tests. Rural villages under subsistence agriculture and urban settlements under cash economy. Adult males and females (n=33) including 16 rural villagers and 17 urban migrants. Step exercise test. There were significant regional differences in BMR (per body weight) in both sexes. The BMR predicted by Schofield equation correlated with the measured BMR (-1 to+3%), while the BMR predicted by Henry and Rees equations under-estimated the measured BMR by 6-11%. NME was higher in urban subjects with larger body size than in rural subjects for both sexes, albeit insignificantly. NME tended to be higher with increased stepping level in both sexes. Urban migrants had lower BMR than rural dwellers, and the BMR predicted by Schofield equation correlated with the measured BMR in both sub-groups.

Energy expenditure at rest and during sleep in children with Prader-Willi syndrome is explained by body composition

Obesity in Prader-Willi syndrome (PWS) seems to be related to a low basal metabolic rate (BMR). In addition, abnormal sleep patterns reported in PWS might affect sleeping metabolic rate (SMR). Our objective was to assess BMR and SMR adjusted for fat-free mass in young PWS patients. Subjects were 17 PWS patients (10 females and 7 males aged 7.5-19.8 y) and 17 obese control subjects matched for sex and bone age. SMR was measured in a respiratory chamber, BMR with a ventilated-hood system, and body composition by deuterium dilution. BMR and SMR were significantly lower in the PWS group than in the control group (5.36 +/- 1.18 and 4.62 +/- 1.08 MJ/d compared with 6.38 +/- 1.55 and 5.60 +/- 1.52 MJ/d, respectively; P < 0.05). When fat-free mass was included in the analysis, multiple regression showed no differences in BMR and SMR between groups. When weight was included in the analysis instead of fat-free mass, SMR was lower in the PWS group. Fat-free mass was lower in the PWS group both as an absolute value and when adjusted for height. BMR and SMR are low in young patients with PWS because of a low fat-free mass.

Lack of association between changes in plasma leptin concentration and in food intake during the menstrual cycle.

Changes in plasma leptin concentration and food intake occur during the menstrual cycle; because leptin regulates food intake, one could hypothesize that changes in plasma leptin concentration and in food intake are associated throughout the menstrual cycle. However, no data have ever been provided to support such a relationship. The aim of our study was to investigate, during the different phases of the menstrual cycle, (a) the changes in plasma leptin concentration and, if such changes were demonstrated, (b) the potential relationship between the changes in plasma leptin concentration and food intake. The study was designed as an observational study. The plasma leptin concentration was determined in 16 healthy, young women during different phases of the menstrual cycle. At the same time, the basal metabolic rate (BMR), respiratory quotient (RQ) and food intake (FI) were also determined. The plasma leptin concentration increased throughout the menstrual cycle (P < 0.01 for trend) and was significantly correlated with plasma progesterone concentration (r = 0.55, P < 0.007, for follicular phase, r = 0.58, P < 0.02, for the periovulatory period and r = 0.57, P < 0.02, for the luteal phase). No significant differences in BMR and fasting RQ throughout the different phases of the menstrual cycle were found. In contrast, FI significantly declined in the periovulatory phase. No significant correlations between BMR, RQ and FI values and fasting plasma leptin concentration at all menstrual phases were found. Changes in plasma leptin concentration and in food intake were found at different phases of the menstrual cycle. Nevertheless, no correlation among those parameters at any phase of the menstrual cycle was observed.

Metabolic correlates of selection for swim stress-induced analgesia in laboratory mice.

The upper limits of metabolic rates and the links between maximal and resting metabolic rates in vertebrates have recently received a lot of attention, mainly due to their possible relationship to the evolution of endothermy. We measured peak metabolic rates during 3 min swimming in 20 degrees C water (Vo2swim), maximal metabolic rate (Vo2max) in -2.5 degrees C Helox, and basal metabolic rate (BMR) in two lines of mice selected for high (HA) and low (LA) swim stress-induced analgesia (SSIA). We found that exercise combined with heat loss used for producing SSIA also acted as a selection agent, resulting in a 15% HA/LA line difference in Vo2swim. Core body temperature of HA mice (characterized by lower Vo2swim) was also on average 3.2 degrees C lower than that of LA mice. Furthermore, Vo2max of HA mice was lower than that of LA mice by 8% and accompanied by larger hypothermia. Thus mice with exceptionally high (or low) Vo2max tended to have exceptionally high (or low) Vo2swim, resulting in a positive correlation between Vo2swim and Vo2max. All these suggest that selection for SSIA produced genetically correlated responses in both Vo2swim and Vo2max. However, we did not observe HA/LA differences in BMR. Hence, changes in resting and maximum metabolic rates are not necessarily correlated. We hypothesize that the lack of such a correlation was partially due to the modulation of metabolic responses by SSIA.

Phylogenetic Analysis of Avian Energetics: Passerines and Nonpasserines Do Not Differ

We reevaluated comparative data on avian metabolic rates, using two recently developed statistical techniques for analysis of phylogenetically dependent data: Felsenstein's method of independent contrasts and Monte Carlo simulation. Contrary to the results of previous studies, our results found no significant differences in basal metabolic rate between passerine and nonpasserine species, once both phylogeny and body mass effects are accounted for. The common assumption that species from "extreme" groups (such as ratites, columbids, and shorebirds) differ energetically from other, "conventional" birds was not supported by our analyses. Because empirically based allometric relationships are critically dependent on the underlying assumptions of the statistical model, so-called adaptive explanations of observed departures from expectation should be corroborated by experimental data and alternative evolutionary models.

Childhood obesity: pathophysiology and treatment.

Childhood obesity is among the most difficult problems which pediatricians treat. It is frequently ignored by the pediatrician or viewed as a form of social deviancy, and blame for treatment failure placed on the patients or their families. The definition of obesity is difficult. Using total body electrical conductivity (TOBEC) technology, total body fat ranges between 12% and 30% of total body weight in normal children and adolescents. This is influenced not only by age, but also by physical fitness. Anthropometry is the easiest way to define obesity. Children whose weight exceeds 120% of that expected for their height are considered overweight. Skinfold thickness and body mass index are indices of obesity that are more difficult to apply to the child. Childhood obesity is associated with obese parents, a higher socioeconomic status, increased parental education, small family size and a sedentary lifestyle. Genetics also clearly plays a role. Studies have demonstrated that obese and non-obese individuals have similar energy intakes implying that obesity results from very small imbalances of energy intake and expenditure. An excess intake of only 418 kJ per day can result in about 4.5 kg of excess weight gain per year. Small differences in basal metabolic rate or the thermic effects of food may also account for the difference in energy balance between the obese and non-obese. In the Prader Willi Syndrome, there appears to be a link between appetite and body fatness. When placed on growth hormone, lean body mass increases, body fat decreases, sometimes to normal, and appetite becomes more normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Energetic Influences on the Life History of Glaucomys volans

Glaucomys volans is nocturnal, active during the winter, and has a low metabolic rate and conductance for its size. Body mass of G. volans was greater in winter than in summer, but there were no seasonal differences in basal metabolic rate or conductance. Energetic constraints may partially explain why many life-history characteristics of this species are relatively conservative compared to diurnal tree squirrels and to other mammals of similar mass.

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.

Basal metabolic rate and physique of Gurkha and British soldiers stationed in Britain

Measurements of basal metabolic rate (BMR) and physique were made on Gurkha soldiers stationed in Britain, and on British controls matched by body weight and occupational background. Gurkhas were significantly shorter, with greater body mass index, calf circumference and subscapular skinfold thickness than the European controls, although there was no difference in BMR between the two groups. For the Gurkhas, linear regression analysis incorporating factors which may influence BMR showed a positive relationship between the length of time since leaving Nepal and BMR, supporting the view that Asians living in temperate regions have higher BMR than those living in the tropics.

Energetic cost of standard activities in Gurkha and British soldiers

Measurements of basal metabolic rate and energy expenditure at lying, sitting, standing, and performing a step test at four levels of exercise, were made on Gurkha soldiers stationed in Britain and on British controls matched by body weight and occupational background. There was no significant difference in basal metabolic rate (BMR), nor in the energy cost of lying, sitting and standing between the two groups. Gurhas showed significantly lower gross and net energy expenditure, and so significantly greater net mechanical efficiency, at the lower levels of step exercise. The ratio of gross energy expenditure to BMR was lower in Gurkhas at the lowest rates of stepping compared with the British controls. These results suggest that the energy cost of some physical activities expressed as multiples of BMR may not be constant across populations.

The influence of different methods on basal metabolic rate measurements in human subjects

While collating basal metabolic rate (BMR) measurements made worldwide it becomes important to know how different instruments compare with each other and whether errors in methodology could account for the differences in BMRs measured. BMRs of 34 healthy individuals were measured by using five different instruments in various combinations. Results show that energy outputs were comparable between the oxylog. Hartmann and Braun Metabolator, ventilated tent and hood, and whole-body indirect calorimeter: small differences, if any, were not statistically significant. However, significant interactions existed between subjects with the ventilated tent and hood and calorimeter when measurements were taken in subjects who were unaccustomed to the apparatus. When converting O2-consumption measurements to energy output, some instruments make assumptions that introduce a variable error in the final result, which may lead to systematic errors during the compilation of large databases of human BMRs.

Fat feeding causes widespread in vivo insulin resistance, decreased energy expenditure, and obesity in rats.

High levels of dietary fat may contribute to both insulin resistance and obesity in humans but evidence is limited. The euglycemic clamp technique combined with tracer administration was used to study insulin action in vivo in liver and individual peripheral tissues after fat feeding. Basal and nutrient-stimulated metabolic rate was assessed by open-circuit respirometry. Adult male rats were pair-fed isocaloric diets high in either carbohydrate (69% of calories; HiCHO) or fat (59% of calories; HiFAT) for 24 +/- 1 days. Feeding of the HiFAT diet resulted in a greater than 50% reduction in net whole-body glucose utilization at midphysiological insulin levels (90-100 mU/l) due to both reduced glucose disposal and, to a lesser extent, failure to suppress liver glucose output. Major suppressive effects of the HiFAT diet on glucose uptake were found in oxidative skeletal muscles (29-61%) and in brown adipose tissue (BAT; 78-90%), the latter accounting for over 20% of the whole-body effect. There was no difference in basal metabolic rate but thermogenesis in response to glucose ingestion was higher in the HiCHO group. In contrast to their reduced BAT weight, the HiFAT group accumulated more white adipose tissue, consistent with reduced energy expenditure. HiFAT feeding also resulted in major decreases in basal and insulin-stimulated conversion of glucose to lipid in liver (26-60%) and brown adipose tissue (88-90%) with relatively less effect in white adipose (0-43%). We conclude that high-fat feeding results in insulin resistance due mainly to effects in oxidative skeletal muscle and BAT.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy Scaling in Marsupials and Eutherians

Marsupials have been shown to have basal metabolic rates below those of eutherian mammals. Now metabolic rates below thermoneutrality are found to be equivalent in both taxa. Two models are proposed to explain the observed metabolic patterns: in one, marsupials differ only in having reduced basal metabolic rates; in the other, the reduced marsupial basal metabolic rates combined with a reduced body temperature and elevated conductance. The metabolic costs of existence below thermoneutrality appear to be similar for both taxa. The difference in basal metabolic rate may be of energetic significance or merely a phylogenetic coincidence.

Calorigenic response in obese and nonobese women

The calorigenic response to a high protein test meal was studied in women with a history of childhood onset obesity. Obese and nonobese individuals were fasted overnight and basal oxygen consumptions determined the following morning. A semisynthetic 823 kcal high protein test meal was ingested within a 1-hr period followed by hourly determinations of oxygen consumption and plasma levels of insulin, free fatty acids, triglycerides, glucose, amino acids, and urea nitrogen. Amino acid levels increased faster and to a higher plateau in the nonobese group, while insulin levels increased and eventually decreased in a similar fashion in both groups. No differences in basal metabolic rate were detected. The postprandial increment in oxygen consumption was significantly less among the obese subjects. Diminished calorigenesis after each meal would result in accumulation of extra calories provided that caloric consumption is not appropriately decreased. These data suggest that a physiological aberration of energy metabolism may contribute to the development of childhood onset obesity.

A comparison of the feeding behaviour of young broiler and layer males

Synopsis The feeding patterns of young broilers were compared with those of young layers to see if any differences might explain the faster growth rate of broilers. During 5 d of observation, the broilers ate almost twice as much as the layers and gained twice as much weight. However, the broilers also converted their food more efficiently and it was thought that this accounted for their faster growth rate. Since there was no difference in the ability of the two strains to digest their food, and since any differences in basal metabolic rate between the strains were likely to be small, it was suggested that the layer strain probably expended more energy on various behavioural responses. The broilers spent half as much time feeding as the layers but ate more meals which were larger and of shorter duration than those of the layers. Although both strains showed the same daily pattern of food consumption, their patterns of feeding activity differed markedly and in general feeding activity bore little relation to food intake.

Basal metabolic rate and lipid and liver glycogen in mice infected by the nematode Nematospiroides dubius

The basal metabolic rate ( BMR) of mice losing weight about two weeks after infection by Nematospiroides dubius was lower than that of uninfected mice gaining weight when fed ad libitum or losing weight on quantitatively reduced rations. There was no difference in BMR between the latter two groups. Following the injection of 14C-glucose, the high specific activity of expired CO 2 from infected and reduced ration mice was considered to be due to the utilization of energy reserves. The levels of lipid and liver glycogen were low in these two groups of mice and their specific activities, particularly in the severely affected animals, were high. It was concluded that the depressed BMR of infected mice is unrelated to anorexia, which did, however, explain the low levels of lipid and liver glycogen.

Gaseous Metabolism and Water Relations of the Zebra Finch, Taeniopygia castanotis

Gaseous Metabolism and Water Relations of the Zebra Finch, Taeniopygia castanotis

Basal Metabolic Rate, Pulse Rate, Respiration Rate, and Certain Organ Weights in Relation to Neonatal Iron Deficiency Anemia in Dairy Calves

Summary An effort was made to determine how and to what extent calves born with iron-deficiency anemia were able to compensate physiologically for their low oxyhemoglobin content. Pulse rate was significantly elevated in nine anemic calves (oxyhemoglobin 9 g/100ml) throughout the 3-wk period of observation following birth. No differences in respiration rate were noted between the two groups of calves. Measurements of basal metabolic rate (BMR) soon after birth and before feeding were significantly higher in the anemic calves. Thereafter, differences in BMR were not significantly different to 3 wk of age. No difference was found in the spleen weight of 22 normal male calves compared with nine male anemic calves slaughtered at birth. Average liver weight of the anemic calves was significantly higher. Heart weights obtained on four of the anemic calves were not different from eight normal calves with which they were compared. Apparently sufficient physiological compensation resulted through increased pulse rate and perhaps other unmeasured effects to allow the normal development of the anemic newborn calves, under the environmental conditions that existed.