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PubMed2001

Prediction of basal metabolism from organ size in the rat: relationship to strain, feeding, age, and obesity.

Use of the weight of various organs and tissues together with their specific metabolic activity for prediction of basal metabolism (BM) seems to be promising. In this study we compared the use of this method with those based on simple or multiple regression analyses. We observed that 97.4% of differences in BM in a group of nine adult male Wistar rats weighing 273--517 g could be accounted for by changes in tissue and organ weights. BM measured in lean Zucker and Sprague-Dawley rats did not diverge from the prediction of the model by >1.6%. According to the organ-based model as well as multiple regression analyses, but not simple regression analyses, BM was increased 18--21% in young rats, decreased 6--7% in food restricted/refed rats, and decreased 19--21% in aged rats. Only with obese rats did the predictions of the two methods diverge. The main reason for this discrepancy seems to be the way adipose tissue size and metabolism are taken into account.

Aging↗
PubMedDate not supplied

The allometry of avian basal metabolic rate: good predictions need good data.

Basal metabolic rate (BMR) is often predicted by allometric interpolation, but such predictions are critically dependent on the quality of the data used to derive allometric equations relating BMR to body mass (Mb). An examination of the metabolic rates used to produce conventional and phylogenetically independent allometries for avian BMR in a recent analysis revealed that only 67 of 248 data unambiguously met the criteria for BMR and had sample sizes with n>/=3. The metabolic rates that represented BMR were significantly lower than those that did not meet the criteria for BMR or were measured under unspecified conditions. Moreover, our conventional allometric estimates of BMR (W; logBMR=-1.461+0.669logMb) using a more constrained data set that met the conditions that define BMR and had n>/=3 were 10%-12% lower than those obtained in the earlier analysis. The inclusion of data that do not represent BMR results in the overestimation of predicted BMR and can potentially lead to incorrect conclusions concerning metabolic adaptation. Our analyses using a data set that included only BMR with n>/=3 were consistent with the conclusion that BMR does not differ between passerine and nonpasserine birds after taking phylogeny into account. With an increased focus on data mining and synthetic analyses, our study suggests that a thorough knowledge of how data sets are generated and the underlying constraints on their interpretation is a necessary prerequisite for such exercises.

Analysis of Variance↗
PubMed2004

Individual variation and repeatability of basal metabolism in the bank vole, Clethrionomys glareolus.

Basal metabolic rate (BMR) is a fundamental energetic trait and has been measured in hundreds of birds and mammals. Nevertheless, little is known about the consistency of the population-average BMR or its repeatability at the level of individual variation. Here, we report that average mass-independent BMR did not differ between two generations of bank voles or between two trials separated by one month. Individual differences in BMR were highly repeatable across the one month interval: the coefficient of intraclass correlation was 0.70 for absolute log-transformed values and 0.56 for mass-independent values. Thus, BMR can be a meaningful measure of an individual physiological characteristic and can be used to test hypotheses concerning relationships between BMR and other traits. On the other hand, mass-independent BMR did not differ significantly across families, and the coefficient of intraclass correlation for full sibs did not differ from zero, which suggests that heritability of BMR in voles is not high.

Analysis of Variance↗
PubMed1992

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.

Acromegaly↗
PubMed2001

[Calculating the basal metabolic rate and severe and morbid obesity].

BACKGROUND AND OBJECTIVE: The aim of this study was to evaluate the currently available predictive equations for basal metabolic rate (BMR) in subjects with obesity class II and III, and to assess the contribution by the components of a two-compartment model of body composition, namely the lean body mass (LBM) and the fat mass (FM) to the prediction. A second objective was to examine the reliability of the Harris Benedict equation in obese subjects, especially with a weight > or = 120 kg. PATIENTS AND METHODS: In 43 patients (age range 18 to 61 years, 5 men, 38 women) with obesity class II and III (body mass index, BMI, mean +/- SD 45.6 kg/m2 +/- 5.4 kg/m2, range 37.1-58.6 kg/m2) basal metabolic rate BMR was determined using indirect calorimetry (Deltatrac MBM, Datex, Instrumentarium Corp., Helsinki, Finnland) and the components of body composition were determined using the bioelectrical-impedance-analysis (BIA) method (BIA, Akern-Gerät, RJL Systems, Detroit). Calculated BMR was compared with measured BMR. RESULTS: The best fitting equations for predicting BMR in these 43 severe und morbidly obese subjects were the Harris-Benedict (ratio calculated BMR to measured, BMR mean +/- SD%; correlation coefficient r = 101 +/- 12.9; 0.69), the Jensen (101.5 +/- 12.3; 0.74), the Nelson (99.3 +/- 11.4; 0.76) and the Cunningham equation (98.9 +/- 11.7; 0.74). The predictive value of the original Harris-Benedict equation was slightly different from modified Harris-Benedict equation, which was recalculated by Roza et al. (101.1 +/- 12.9; 0.69 vs. 99.7 +/- 12.8; 0.69). In the group of the 22 subjects with a body weight > or = 120 kg ratio of estimated values for BMR using original Harris-Benedict equation to measured BMR was 102.2 +/- 15.4% (mean +/- SD%, r = 0.61), respectively 93.2 +/- 14.5% (r = 0.50) when weight was set at 120 kg due to current recommendations. The ratio calculated BMR/measured BMR according to the Nelson equation in this subgroup was 101.0 (12.1/0.74). CONCLUSION: In patients with obesity class II and III the equation of Harris-Benedict predicted the average BMR with acceptable precision for clinical use and was better fitting than most of the currently available predictive equations for basal metabolic rate (BMR). However, the recalculated version (by Roza et al.) was more accurate and should therefore be used instead of the original equation: BMR (men) = 88.362 + 4.799 x (length) + 13.397 x (weight) - 5.677 x (age); BMR (women) = 447.593 + 3.098 x (length) + 9.247 x (weight) - 4.330 x (age). The Nelson equation, including not only LBM but FM as additional predictor, was the best predicting equation ([108 LBM + 16.9 FM]0.239). Harris-Benedict equation had sufficient precision also in extreme obese subjects with a body weight > or = 120 kg, so there is no need for adaptation.

Adolescent↗
PubMed1992

Basal metabolism adds a significant offset to unloaded myocardial oxygen consumption per minute.

Myocardial oxygen consumption (MVO2) includes components for 1) mechanical energy generation, 2) activation, and 3) basal metabolism. Whereas the first two components are expected to increase in proportion with heart rate, a significant basal level of metabolism would consume oxygen even if the heart rate were zero. Contrary to this expectation, however, a previous study reported that, during unloaded beats, MVO2 per beat (which includes basal metabolism) was independent of heart rate. Accordingly, unloaded MVO2 per minute would extrapolate to zero at zero heart rate; this result is unexpected considering basal metabolism. To resolve this inconsistency, we varied heart rate over a wide range after inducing atrioventricular block in eight isolated cross-circulated canine hearts that contracted isovolumically. We examined whether a term representing rate-independent basal metabolism was needed to describe MVO2 per minute. Mechanical energy generated by the left ventricle was evaluated from the pressure-volume area, which was altered by changing isovolumic ventricular volume over at least five levels at each heart rate. Contractility, evaluated by the slope of the end-systolic pressure-volume relation, did not vary significantly with heart rate in this study. In contrast to the previous report, unloaded MVO2 per beat (i.e., MVO2 extrapolated to a pressure-volume area of zero) was not constant but fell monotonically with increases in heart rate in every heart. We considered that this trend was caused by a significant rate-independent basal level of MVO2 per minute. Multiple linear regression analysis confirmed that this rate-independent basal term differed significantly from zero in seven of the eight hearts studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Validation of three predictive equations for basal metabolic rate in adults.

OBJECTIVE: To cross-validate three predictive set of equations for basal metabolic rate (BMR) developed by Schofield (Schofield database), Henry (Oxford database) and Cole (Oxford database) using mean values for age, weight, height and BMR of published studies. DESIGN: Literature review of studies published from 1985 to March 2002. SETTING: All studies selected used appropriate methods and followed conditions that met the criteria established for basal metabolism, were performed in healthy adults, and were not part of the Schofield or Oxford database. SUBJECTS: A total of 261 groups of men and women from 175 studies were selected and categorised in three age groups (18.5-29.9, 30.0-59.9, > or = 60 years old) and three body mass index (BMI) groups (normal weight, overweight and obese). RESULTS: Linear regression and concordance correlation analysis showed that the three sets of equations had the same association and agreement with measured BMR, across gender, age, and BMI groups. The agreement of all equations was moderate for men and poor for women. The lowest mean squared prediction errors (MSPRs) were given by Henry equations in men and Cole equations in women. Henry and Cole equations gave lower values than Schofield equations, except for men over 60 years of age. Henry equations were the most accurate in men. None of the three equations performed consistently better in women. CONCLUSION: These results support the use of Henry equations in men with a wide range of age and BMI. None of the proposed predictive equations seem to be appropriate to estimate BMR in women.

Adolescent↗
PubMed1987

Basal metabolic rate of Indian men: no evidence of metabolic adaptation to a low plane of nutrition.

Basal metabolic rate (BMR) was measured in 58 men of a rural Indian population who had low body weight and body fat stores. Comparisons of subgroups of subjects of different socio-economic status and different nutritional status showed no evidence of differences in BMR when corrected for differences in body weight and body fat content. This suggests that metabolic adaptation did not account for differences in absolute BMR between subgroups of this population. The BMR values agreed well with values predicted by equations based on BMR measurements in Asian men of higher body weight, but were below values predicted by the new FAO/WHO/UNU prediction equations by an average of 12.1 per cent (P less than 0.0001). This overprediction could be a reflection of allometric or climatic influences on BMR rather than evidence for metabolic adaptation to a low plane of energy nutrition.

Adaptation, Physiological↗
PubMed1983

Effects of glucagon on basal metabolic rate and oxidative phosphorylation of rat liver mitochondria.

Glucagon produced fast but transient stimulation of respiration rates in state 3 and state 4 rat liver mitochondria when either succinate or beta-hydroxybutyrate was used as substrate. Stimulation was already detectable 7.5 minutes after glucagon injection. Glucagon also clearly activated basal metabolic rate, and its effects on oxygen consumption rates reached their maximum 20 to 30 minutes after injection. Pretreatment with cycloheximide blocked most activation by glucagon of both oxidative phosphorylation and basal metabolic rate, but did not affect its enhancement of glycaemia. The rise in basal metabolic rate was the direct result of glucagon's effect on mitochondria, which was secondary to nucleocytoplasmic protein synthesis.

Animals↗
PubMed1994

Decremental reset in basal metabolism during 20-days bed rest.

Changes in basal metabolism during 20 days bed rest were measured in 9 young healthy males and 5 females. Food intake was unrestricted and supplementary meals were allowed. All food intake was monitored. A special sleeping pattern was not enforced, although an ordinary day-night diurnal rhythm was kept in the rooms. Body temperatures were measured daily every 2 hours from 7:00 to 22:00. Basal oxygen uptake decreased significantly during the first 10 days of bed rest and levelled off during the following 10 days. Body weight and composition remained substantially unchanged in spite of a decreased energy consumption during the bed rest. In conclusion, basal VO2 was reset at a decreased level during the first 10 days of bedrest with no relationship to the dietary energy intake or to the body temperature, while no more change took place during the following 10 days.

Adult↗
PubMed1990

Basal metabolic rate in monozygotic and dizygotic twins.

The basal metabolic rate (BMR) was determined in 14 pairs of monozygotic (MZ; 11 females, 3 males) and 12 pairs of dizygotic (DZ; 10 females, 2 males) twins, with mean ages of 22.7 and 26 years. Zygosity was confirmed using DNA fingerprinting. When BMR was expressed as kJ/d, kJ/kg/d and kJ/kg FFM/d significant intra-class correlation coefficients were observed in the MZ twins of 0.82, 0.79 and 0.85, respectively. The DZ twins showed much lower intra-class correlations coefficients of 0.1, 0.07 and -0.04. Although the results of the study suggest a likely genetic component to the variation in BMR, they should be interpreted with caution as heritability estimates vary with the method of calculation. These will be critically discussed in the paper.

Adult↗
PubMed1985

Daily energy expenditure and basal metabolic rates of patients with spinal cord injury.

Basal metabolic rate (BMR) and daily energy expenditure were measured in 48 men with complete traumatic transections of the spinal cord. Subjects were classified according to their residual motor function as high or low quadriplegic (HQ, LQ) or as high or low paraplegic (HP, LP). Measured BMR was lower than predicted BMR in almost all of the subjects and was significantly lower in the HQ group than in the other groups. High quadriplegics also expended significantly less energy while awake and over a 24-hour period than did the other groups. Measurements of BMR and total energy expenditure were significantly correlated with the level of lesion. The data provide a basis for establishing guidelines on the average energy needs of patients with spinal cord injury.

Adult↗
PubMed1988

The effect of the preceding day's protein intake on basal metabolic rates in young adults.

1. Changes in basal metabolic rates (BMR), following alterations in the preceding day's dietary protein (8.6, 11.5 and 14.0% of energy) were studied in eight, young, healthy adults over 4 d. 2. Results showed a significant training effect, with BMR values 4.8% lower on day 4 of the study period. Analysis of the results by ANOVA revealed a significant interaction between subjects and diets (P less than 0.005), a significant difference between subjects but no differences in BMR due to the protein content of the diets. 3. Mean coefficient of variation (CV) for intra- and inter-individual differences in BMR from day-to-day was of the order of 4 and 9% respectively. 4. Changes in protein content of the preceding day's diet do not influence variations in BMR which appear to be random in nature with a true CV of 3.8%.

Adult↗
PubMed1991

New predictive equations for the estimation of basal metabolic rate in tropical peoples.

The measurement of basal metabolic rate (BMR) is an important element in the estimation of energy requirements in man. Based on a survey of 2822 BMR measurements conducted in the tropics, a series of new predictive equations to estimate BMR in tropical peoples is presented. These new equations based on bodyweight show that the current FAO/WHO/UNU predictive equations overestimate BMR of peoples living in the tropics by an average of 8 per cent, and by up to 11.5 per cent for males over 30 years old. These differences were significant over between 65 and 100 per cent of the normal bodyweight range found in our data, for both males and females over 10 years old. However, for younger ages, 3-10 years, the FAO/WHO/UNU equations predicted BMR quite accurately. The inclusion of height made no significant difference to the predictive equation. Although caution must be exercised in interpreting these results, it is concluded that the lower BMR in the tropics appears to be a general and genuine phenomenon in adults. Further discussion of energy requirements in tropical peoples must consider these observed deviations in BMR from the FAO/WHO/UNU predictive equations.

Adolescent↗
PubMedDate not supplied

[Evaluation of the basal metabolic requirements of patients with grave brain lesions].

Basal metabolism (BM) was studied in 26 patients with a brain lesion treated at the neuro-resuscitation department. The complex of examination methods included dynamic appraisal of total energy expenditure and contribution of carbohydrates, fats, and proteins to the total energy expenditures by indirect calorimetry in combination with tests for daily nitrogen excretion, determination of biochemical indices characterizing BM: total lymphocyte count, concentration of blood total protein, albumin, blood urea nitrogen, and creatinine. It is shown that the character and degree of changes of BM depend on the clinico-neurological features of the disease in the postoperative (posttraumatic) period. Aspontaneity of various genesis leads to reduction of total energy expenditure by 18-25% of the normal values. Increased motor activity and the spasmodic syndrome increase total energy expenditure by 30-50%. Concurrent development of infectious complications increases total energy expenditure and changes its structure at the cost of increase of protein expenditure (proteins become responsible for up to 50% of energy expenditure). Indirect calorimetry in combination with tests for daily nitrogen losses is recommended for the evaluation and correction of BM disorders in patients requiring intensive therapy.

Adolescent↗
PubMed2007

Associations between basal metabolic rate and reproductive performance in C57BL/6J mice.

Basal metabolic rate (BMR) is highly variable, both between and within species. One hypothesis is that this variation may be linked to the capacity for sustained rate of energy expenditure, leading to associations between high BMR and performance during energy-demanding periods of life history, such as reproduction. However, despite the attractive nature of this hypothesis, previous studies have failed to show an association between BMR and fecundity. Our approach was to mate 304 C57BL/6J mice and allow them to wean pups before measuring BMR by indirect calorimetry. We did not find an association between BMR and litter mass, size or pup mass at birth or weaning that could not be accounted for by the body mass of the dam. There was also no relationship between BMR (or BMR corrected for body mass) and birth or weaning success, losses during weaning, or sex ratio. However, a significant relationship was found between BMR and gestational weight loss indicative of foetal resorption. This suggests that during pregnancy the available energy may be limited and partitioned away from the growing foetus and towards maintenance of the mother. In this context, a high BMR may actually be disadvantageous, conflicting with the idea that high BMR may bring reproductive benefits.

Animals↗
PubMed1999

New equations to estimate basal metabolic rate in children aged 10-15 years.

OBJECTIVE: To develop new equations for the estimation of basal metabolic rate in children aged 10-15 years, and to evaluate the impact of including pubertal stage into the equations. DESIGN: Mixed longitudinal. SETTING: The children were recruited from schools in Oxford, and the measurements were made in the schools. SUBJECTS: 195 school children, aged 10-15 years, were recruited in three cohorts. The gender distribution of the subjects was 40% boys and 60% girls. METHODS: Basal metabolic rate (BMR) was measured, by indirect calorimetry, at 6-monthly intervals for 3 years. Anthropometric data, height, weight, body breadths and skinfold measurements (biceps, triceps, subscapular, suprailiac and medial calf) were collected on each occasion. Fat and fat-free mass was calculated from the skinfold measurements. Pubertal development was also assessed on annually by paediatricians. Pubic hair (PH) and gonad (G) development was assessed in boys and breast (B) development in girls. The girls were questioned about menarche. Stepwise multiple regression analysis was used to develop and assess new formulae for BMR that also incorporate pubertal development. RESULTS: The mean BMR measured was 5.754 (s.d. 0.933) MJ/day (138 (s.d. 22) kJ/kg body wt/day) in the boys (n = 351) and 5.476 (s.d. 0.725) MJ/day (121 (s.d. 20) kJ/kg body wt/day) in the girls (n = 554). Weight was the most important factor in developing the regression equations for the calculation of BMR in both sexes (R2 = 0.61 and 0.52 for boys and girls, respectively). Stepwise multiple regression analyses, with independent variables such as gender, weight, height, puberty stage and skinfolds, allowed several BMR regression equations to be developed. The inclusion of the menarche status in the regression equations significantly (P < 0.05) improved BMR estimation in the pre-menarche girls. Boys, pubertal stage as assessed by Pubic Hair (PH) and Gonadal Stage (G) did not contribute to a significant improvement in BMR estimation, except for 11-year-olds. CONCLUSIONS: The inclusion of pubertal stage afforded only minor improvements in the derivation of regression equations for the estimation of BMR of children aged between 10 and 15 years.

Adolescent↗