Energetics and litter size variation in domestic dog Canis familiaris breeds of two sizes

We measured resting metabolic rate (RMR), daily energy expenditure (DEE) and metabolisable energy intake (MEI) in two breeds of dog during peak lactation to test whether litter size differences were a likely consequence of allometric variation in energetics. RMR of Labrador retrievers (30 kg, n=12) and miniature Schnauzers (6 kg, n=4) averaged 3437 and 1062 kJ/day, respectively. DEE of Labradors (n=6) and Schnauzers (n=4) averaged 9808 and 2619 kJ/day, respectively. MEI of Labradors (n=12) was 22448 kJ/day and of Schnauzers (n=7) was 5382 kJ/day. DEE of Labrador pups (2.13 kg, n=19) was 974 kJ/day and Schnauzers (0.89 kg, n=7) were 490 kJ/day. Although Labradors had higher MEIs than Schnauzers during peak lactation, there was no difference in mass-specific energy expenditure between the two breeds. Hence, it is unlikely that litter size variation is a likely consequence of differences in maternal energy expenditure. Individual offspring were relatively more costly for mothers of the smaller breed to produce. Therefore, litter size variations were consistent with the expectation that smaller offspring should be more costly for mothers, but not that smaller mothers should per se invest more resources in reproduction.     

Renal excretion of 8-oxo-7,8-dihydro-2(')-deoxyguanosine: degradation rates of RNA and metabolic rate in humans

Renally excreted 8-oxo-7,8-dihydro-2(')-deoxyguanosine (oxo(8)dG) is a potential marker of oxidative DNA damage by reactive oxygen species. Whole-body degradation rates of t- and rRNA are potential indicators of the resting metabolic rate (RMR). Excretion rates of oxo(8)dG and degradation rates of t- and rRNA were determined in healthy non-smoking adults and children. RMR (indirect calorimetry; 14 children, 16 adults), total energy expenditure (TEE; doubly labelled water technique; 4 children, 6 adults), and lean body mass (LBM; dual-energy X-ray absorptiometry; 14 children, 16 adults) were also measured. Degradation of t- and rRNA (micromol/d/kg LBM; 4 children, 6 adults) was highly correlated with RMR (kJ/d/kg LBM), r=0.867 (p<0.005) and 0.959 (p<0.001), respectively. Excretion of oxo(8)dG (pmol/d/kg LBM; 14 children, 16 adults) was not significantly correlated with RMR (p>0.05). Neither excretion of oxo(8)dG nor degradation of RNA was significantly correlated with TEE (kJ/d/ kg LBM) (p>0.05). In healthy subjects further factors, other than the metabolic rate, seem to influence the excretion rate of oxo(8)dG. The degradation rates of t- and rRNA seem to be appropriate indicators of the RMR.     

Energy Expenditure in Lean and Obese Prepubertal Children

The relationship between energy expenditure and obesity was examined in prepubertal children. Consenting fifth graders underwent Tanner Staging, weight, height and skinfold measurements. Subjects were selected for further study to obtain equal numbers of girls and boys with a wide range of body composition. Weight, total daily energy expenditure (TDEE) by doubly labeled water (DLW), resting metabolic rate (RMR), and body composition were measured. Children were grouped into level of obesity based on tertiles of subscapular plus triceps skinfolds. The skinfold tertiles did quite well in grouping subjects by degree of obesity, as differences in percent fat in each tertile were significantly different. There were no differences in fat-free mass between the groups, while the highest tertile group weighed 14 kg more than the lowest. For DLW, energy expenditure was calculated using day 8 and day 9 urine samples as the final time point to examine precision. Mean energy expenditure using either day was nearly identical (2220 ± 400 vs. 2300 ± 370 kcal/d), with a CV of the difference of 5.5%. No differences in RMR, energy expended in activity, or TDEE between the three groups were observed. A reduction in RMR or TDEE could not explain differences in obesity in these prepubertal children. However, the fact that the heaviest children expended the same amount of energy in activity and had the same TDEE as the leanest, while weighing 14 kg more, indicates that the obese children had a reduced activity level.     

An Age-Associated Decline in Thymic Output Differs in Dog Breeds According to Their Longevity

The age associated decline in immune function is preceded in mammals by a reduction in thymic output. Furthermore, there is increasing evidence of a link between immune competence and lifespan. One approach to determining thymic output is to quantify signal joint T cell receptor excision circles (sj-TRECs), a method which has been developed and used in several mammalian species. Life expectancy and the rate of aging vary in dogs depending upon their breed. In this study, we quantified sj-TRECs in blood samples from dogs of selected breeds to determine whether there was a relationship between longevity and thymic output. In Labrador retrievers, a breed with a median expected lifespan of 11 years, there was an age-associated decline in sj-TREC values, with the greatest decline occurring before 5 years of age, but with sj-TREC still detectable in some geriatric animals, over 13 years of age. In large short-lived breeds (Burnese mountain dogs, Great Danes and Dogue de Bordeaux), the decline in sj-TREC values began earlier in life, compared with small long-lived breeds (Jack Russell terriers and Yorkshire terriers), and the presence of animals with undetectable sj-TRECs occurred at a younger age in the short-lived breeds. The study findings suggest that age-associated changes in canine sj-TRECs are related to breed differences in longevity, and this research highlights the use of dogs as a potential model of immunosenescence.     

Insulin-like growth factor-1, leptin, body composition, and clinical status interactions in children with cystic fibrosis

BACKGROUND/AIMS: Children with cystic fibrosis (CF) are of increased risk of reduced fat body mass (FBM) and lean body mass (LBM). Serum concentrations of insulin-like growth factor-1 (IGF-1)and leptin could be markers of LBM and/or FBM depletion. To evaluate the relationships between disease activity, body composition, IGF-1 and leptin concentrations in CF children. METHODS: A cross-sectional study with 26 CF children aged 5.0-15.5 years and 33 healthy controls, mean age 9.4 years. Body composition was evaluated by dual-energy X-ray absorptiometry. Fasting blood samples were analyzed for leptin, IGF-1 and IGFBP-3. RESULTS: FBM standard deviation score (SDS; CF boys -0.02 +/- 0.88 vs. 0.78 +/- 0.65, p < 0.01; CF girls -0.37 +/- 1.15 vs. 0.70 +/- 0.97, p < 0.05), leptin concentration (CF boys 2.07 +/- 0.79 vs. 3.07 +/- 1.28 ng/ml, p < 0.05; CF girls 2.71 +/- 0.86 vs. 5.00 +/- 2.95 ng/ml, p < 0.05) and IGF-1SDS (CF boys -1.43 +/- 1.50 vs. -0.32 +/- 0.88, p < 0.05; CF girls -0.66 +/- 1.66 vs. 0.64 +/- 0.57, p < 0.01) were lower in CF children compared to controls. Shwachman score was the strongest predictor of lean body mass (R = 0.63). Leptin levels explain 60% of the variability in FBM. CONCLUSION: Serum concentrations of IGF-1 and leptin are decreased in children with CF and are associated with clinical conditions and body composition.     

Energetic costs of parasitism in the Cape ground squirrel Xerus inauris

Parasites have been suggested to influence many aspects of host behaviour. Some of these effects may be mediated via their impact on host energy budgets. This impact may include effects on both energy intake and absorption as well as components of expenditure, including resting metabolic rate (RMR) and activity (e.g. grooming). Despite their potential importance, the energy costs of parasitism have seldom been directly quantified in a field setting. Here we pharmacologically treated female Cape ground squirrels (Xerus inauris) with anti-parasite drugs and measured the change in body composition, the daily energy expenditure (DEE) using doubly labelled water, the RMR by respirometry and the proportions of time spent looking for food, feeding, moving and grooming. Post-treatment animals gained an average 19g of fat or approximately 25kJd-1. DEE averaged 382kJd-1 prior to and 375kJd-1 post treatment (p>0.05). RMR averaged 174kJd-1 prior to and 217kJd-1 post treatment (p<0.009). Post-treatment animals spent less time looking for food and grooming, but more time on feeding. A primary impact of infection by parasites could be suppression of feeding behaviour and, hence, total available energy resources. The significant elevation of RMR after treatment was unexpected. One explanation might be that parasites produce metabolic by-products that suppress RMR. Overall, these findings suggest that impacts of parasites on host energy budgets are complex and are not easily explained by simple effects such as stimulation of a costly immune response. There is currently no broadly generalizable framework available for predicting the energetic consequences of parasitic infection.     

Lower than predicted resting metabolic rate is associated with severely impaired cardiorespiratory fitness in obese individuals

Obese individuals have reduced cardiorespiratory fitness as compared with leaner counterparts. Regular exercise maintains or increases fitness and lean body mass. Lean body mass, in turn, has a direct impact on resting metabolic rate (RMR). Given these relationships, we sought to evaluate the association between RMR and cardiorespiratory fitness in obese individuals. We evaluated 64 obese individuals (78% female) with direct assessment of RMR and cardiorespiratory fitness via breath‐by‐breath measurement of oxygen consumption and carbon dioxide production at rest and during exercise. The mean age and BMI were 47.4 ± 12.2 years and 47.2 ± 9.2 kg/m², respectively. The majority of subjects, 69%, had a measured RMR above that predicted by the Harris‐Benedict equation. Compared with the higher RMR group, those with a lower than predicted RMR had increased BMI, with values of 52.9 vs. 44.7 kg/m², P = 0.001, respectively. Analysis of those demonstrating significant effort during cardiopulmonary exercise testing (peak respiratory exchange ratio ≥1.10) revealed a significantly higher peak oxygen uptake (VO₂ peak) in the higher RMR group (17.3 ± 3.5 ml/min/kg) compared with the lower RMR group (13.6 ± 1.9 ml/min/kg), P = 0.003. In summary, a lower than predicted RMR was associated with a severely reduced VO₂ peak and a higher BMI in this cohort. These data suggest that morbid obesity may be a vicious cycle of increasing BMI, reduced cardiorespiratory fitness, muscle deconditioning, and lower RMR. Collectively, these responses may, over time, exacerbate the imbalance between energy intake and expenditure, resulting in progressive increases in body weight and fat stores.     

Effects of air and water temperatures on resting metabolism of auklets and other diving birds

For small aquatic endotherms, heat loss while floating on water can be a dominant energy cost, and requires accurate estimation in energetics models for different species. We measured resting metabolic rate (RMR) in air and on water for a small diving bird, the Cassin's auklet (Ptychoramphus aleuticus), and compared these results to published data for other diving birds of diverse taxa and sizes. For 8 Cassin's auklets (~165 g), the lower critical temperature was higher on water (21 °C) than in air (16 °C). Lowest values of RMR (W kg?1) averaged 19% higher on water (12.14 ± 3.14 SD) than in air (10.22 ± 1.43). At lower temperatures, RMR averaged 25% higher on water than in air, increasing with similar slope. RMR was higher on water than in air for alcids, cormorants, and small penguins but not for diving ducks, which appear exceptionally resistant to heat loss in water. Changes in RMR (W) with body mass either in air or on water were mostly linear over the 5- to 20-fold body mass ranges of alcids, diving ducks, and penguins, while cormorants showed no relationship of RMR with mass. The often large energetic effects of time spent floating on water can differ substantially among major taxa of diving birds, so that relevant estimates are critical to understanding their patterns of daily energy use.     

Influence of body composition on the metabolic rate of nestling European shags (Phalacrocorax aristotelis)

During the early development of avian nestlings, their mass-specific resting metabolic rate (RMR) changes in a biphasic pattern with the peak value often being much higher than that expected for an adult bird of similar body mass. In the present study we examined the possible influence of variations in the size of internal organs in “setting” the high RMR and peak metabolic rate (PMR) during development in a large altricial species, the European shag (Phalacrocorax aristotelis). Thermoneutral RMR and cold-exposure induced PMR were measured in nestlings 15 days old, the age at which the highest RMR occurred during development. Body mass averaged 414 g. Mean values of RMR and PMR were 5.75 W and 9.08 W, respectively; the RMR value corresponds to approximately 250% of the expected value for an adult non-passerine bird of similar body mass. The masses of all the organs measured (breast and leg muscles, heart, liver, intestine, and kidney) varied isometrically with total body mass. However, large chicks had a significantly lower fractional water content than small chicks, suggesting that the former had achieved a higher level of functional maturity. In contrast to what has been suggested for adult birds in general, the heart and kidney masses of shag nestlings were not significantly correlated with the metabolic rates. The intestine length, in contrast, was highly and positively correlated with both the RMR and the PMR, i.e. intestine length was a better predictor of RMR and PMR than was total body mass. In addition, liver mass was positively correlated with RMR. The results of the present study suggest that the liver in particular may play a key role in establishing the high, mass-specific RMR which is attained during development in bird chicks. Our results also support previous suggestions that early in their development, altricial chicks mainly allocate energy to the growth of `energy-processing' organs (such as the intestine and liver) rather than to `energy-consuming' organs. Accepted: 3 March 1999     

Pattern and cost of weight gain in previously obese women

Weight gain is common among postobese individuals, providing an opportunity to address the cost of weight regain on energy expenditure. We investigated the energy cost of weight regain over 1 yr in 28 women [age 39.5 +/- 1.3 (SE) yr; body mass index 24.2 +/- 0.5 kg/m(2)] with recent weight loss (>12 kg). Body composition, total energy expenditure (TEE) using doubly labeled water, resting metabolic rate (RMR), and thermic effect of a meal (TEM) were assessed at 0 and 12 mo. Metabolizable energy intake (MEI) was calculated from TEE and change in body composition. Fourteen women had a weight gain of 13.2 +/- 2.1 kg. Twelve-month cumulative excess MEI, calculated as the intake in excess of TEE at month 0, was 749 +/- 149 MJ. Of this, 462 +/- 83 MJ (62%) were stored as accrued tissue, and 287 +/- 72 MJ (38%) was increased TEE. Expressed per kilogram of body weight gain, the energy cost of weight gain was calculated to be 54.8 +/- 4.6 MJ/kg. Interestingly, weight regain time courses fell into three distinct patterns, possibly requiring varying countermeasures.     

Relationship Between Circulating Leptin and Energy Expenditure in Adult Men and Women Aged 18 Years to 81 Years

SUSAN B. ROBERTS, MARGERY NICHOLSON, MYRLENE STATEN, GERALD E. DALLAL, ANA L. SAWAYA, MELVIN B. HEYMAN, PAUL FUSS, ANDREW S. GREENBERG. Relationship between circulating leptin and energy expenditure in adult men and women aged 18 years to 81 years. Recent studies suggest that leptin may be an important metabolic signal for energy regulation in rodents, but the role of leptin in human energy regulation remains uncertain. Because adaptive variations in energy expenditure play an important role in human energy regulation, we investigated the relationship between leptin and energy expenditure parameters in 61 weight-stable men and women aged 18 years to 81 years who were not obese. Measurements were made of circulating leptin in the fasting state, body fat and fat free mass, resting metabolic rate (n=61), free-living total energy expenditure (n=52), and the thermic effect of feeding (n=33). After statistically accounting for age, body fat, and fat free mass, there was no association between leptin and any measured energy expenditure parameter. In addition, there was no effect of age on the relationship between circulating leptin and body fat mass. These results indicate that physiological variations in circulating leptin are not linked with adaptive variations in energy expenditure in humans, in contrast to indications of this phenomenon in the ob/ob mouse.     

Dynamics of Change in Total and Regional Body Composition After Gastric Bypass in Obese Patients

Little is known on patterns of change over time in body composition, especially lean body mass (LBM), during massive weight loss after Roux‐en‐Y gastric bypass (RYGB) in obese patients. We performed sequential measurements of total and regional body composition in patients after RYGB, and we compared a subsample of patients after surgery to a nonsurgical control group of similar age and body fatness. We used dual‐energy X‐ray absorptiometry (DXA) before and at 3, 6, and 12 months after RYGB in 42 obese women (before surgery: age 39.5 ± 11.6 years; BMI 44.6 ± 6.1 kg/m²; mean ± s.d.) and in 48 control obese women referred for nonsurgical weight management, before weight loss. During 1‐year follow‐up after RYGB, there was a continuous decrease in body weight (?36.0 ± 12.5 kg at 1 year), total fat mass (FM) (?26.0 ± 9.1 kg), as well as in trunk and appendicular FM. In contrast, the decrease in total LBM (?9.8 ± 4.8 kg at 1 year), as well as in trunk and appendicular LBM, plateaued after 3–6 months. Rates of loss in weight, FM, and LBM were highest during the first 3‐month period after RYGB (6.4 ± 1.8, 4.1 ± 1.7, and 2.3 ± 1.2 kg/month, respectively), then decreased continuously for FM but plateaued for LBM. There was no evidence of a decrease in total, trunk, or appendicular LBM in weight‐reduced subjects compared to the control group. In conclusion, follow‐up of these obese women revealed a differential pattern of change in FM and LBM after RYGB. Despite an important loss in LBM, especially during the 3–6 months of initial period, LBM appears to be spared thereafter.     

The MTHFR gene polymorphism is associated with lean body mass but not fat body mass

Along with aging, human body composition undergoes notable changes and may incur sarcopenia, obesity or osteoporosis. Sarcopenia is related to a wide series of human health problems and can be largely characterized by loss of lean body mass (LBM). Studies have showed relevance of methylenetetrahydrofolate reductase (MTHFR) with variation in LBM and fat body mass (FBM). To test if polymorphism of the MTHFR gene is underlying the pathology of sarcopenia and obesity, we concurrently tested five single nucleotide polymorphisms (SNPs) of the MTHFR gene for association with LBM, FBM and body mass index (BMI) in 405 Caucasian nuclear families comprising 1,873 individuals. After correction for multiple testing, we detected significant associations for LBM with rs2066470 (P = 0.0006), rs4846048 (P = 0.0007) and with rs3737964 (P = 0.004), as well as for BMI with rs4846048 (P = 0.009). Polymorphism of rs2066470 explains 3.67% of LBM variation in this sample. The association between BMI and rs4846048 diminished after adjusting for LBM, suggesting that the association between BMI and rs4846048 is largely due to LBM instead of the fat component. In concert, no significant associations were identified for FBM with any of the studied SNPs. The results of single-locus association analyses were corroborated by haplotype-based analyses. In summary, the MTHFR gene polymorphism is associated with LBM, suggesting that MTHFR may play an important role in LBM variation. In addition, the MTHFR gene polymorphism is not associated with FBM or obesity in this sample.     

Reduced short-term thermic effects of a meal in obese adolescent girls

Post-meal energy expenditure (TEM) was compared for 14 healthy obese (body fat = 45.3%, body mass index, BMI = 35.9 kg m-2) and 9 healthy nonobese (body fat = 20.7%, BMI = 17.8 kg m-2) adolescent girls. The test meal for both groups was a standard 3348.8-kJ, 0.473-1 chocolate milkshake of 15% protein (casein), 40% fat (polyunsaturated/saturated ratio = 0.05; 75 mg cholesterol) and 45% carbohydrate (lactose and sucrose). Glucose, insulin and resting energy expenditure (RMR) were measured at rest prior to meal consumption and 20, 40, 60, 90, and 120 min after the meal. Cumulative net TEM was calculated as the integrated area under the TEM curve with RMR as baseline. Reliability was assessed by retesting 4 subjects, and a placebo effect was tested by administering a flavored energy-free drink. Results indicated high reliability and no placebo effect. The meal resulted in a greater rise in insulin and glucose for the obese compared to the nonobese subjects (P < or = 0.05), and a significant TEM for both groups (P < or = 0.05). The cumulative TEM (W kg-1) was 61.9% greater for the nonobese (P < 0.01) when expressed relative to body mass, and 33.2% greater for the nonobese (P < or = 0.01) when expressed relative to the fat-free body mass. Expressed relative to the meal, the TEM was 25.5% less for the obese (P < 0.01). The data support an energy conservation hypothesis for obese female adolescents.     

Effects of Sibutramine on Resting Metabolic Rate and Weight Loss in Overweight Women

Sibutramine, a monoamine re-uptake inhibitor, has recently been approved by the Food and Drug Administration as a weight loss agent. Sibutramine lowers body-weight in rodents by reducing energy intake and increasing energy expenditure. Sibutramine facilitates weight loss in human subjects, but it is not clear whether it acts on energy intake, energy expenditure, or both. The present study was a randomized clinical trial designed to assess the effects of sibutramine (at 10 or 30 mg/day) on body weight and resting metabolic rate (RMR). Forty-four overweight women were randomized to 1) placebo (n=15); 2) sibutramine at 10 mg/day (n=15) or, 3) sibutramine at 30 mg/day (n=14). All subjects were instructed to consume a 1200 kcal/day diet for 8 weeks while receiving drug or placebo. RMR was assessed by indirect calorimetry at baseline, at 3 hours after the first dose of drug (or placebo), and at the end of the 8-week weight-loss period. Sibutramine reduced body weight-relative to placebo, but there was no difference between weight loss on the two sibutramine doses. No significant differences in RMR between sibutramine and placebo were seen, either 3-hour post dose or after the 8-week weight-loss period. After the weight loss period, all groups were taken off medication and kept weight stable for another 4 weeks. RMR was measured again and was not different among groups. That there was no change in RMR when sibutramine was stopped further suggests that the drug does not directly affect RMR. In summary, while sibutramine was shown to be an effective weightloss agent over 8 weeks, we found no evidence that it increased RMR.     

Resting energy metabolism of Goeldi's monkey (Callimico goeldii) is similar to that of other callitrichids

The resting metabolic rates (RMRs) of six adult Goeldi's monkeys (Callimico goeldii) were measured using standard methods of open circuit respirometry during both the active (daytime) and inactive (nighttime) circadian phases for this species. One subject was measured both while she was pregnant and after she delivered a full-term, stillborn infant. Inactive-phase RMR within thermal neutrality (above 27.5 degrees C) averaged 288.5 +/- 30.8 ml O2/hr; active-phase RMR within thermal neutrality averaged 416.3 +/- 60.9 ml O2/hr. These values are 74.6% and 107.6%, respectively, of the mammalian expected for animals of this body mass. During the inactive phase, metabolic rate increased an estimated 4.3% for every degree decline in temperature below 27.5 degrees C. The RMR in Goeldi's monkey is similar quantitatively and qualitatively to those of other captive callitrichids that have been studied, with active-phase RMR being at or slightly above the mammalian expected, and inactive-phase RMR being significantly reduced. We propose that this circadian pattern of RMR is a consequence of small body size, and is not a specific metabolic adaptation within the Callitrichidae. Thus we predict that metabolic studies measuring both circadian phases in other small primates will also find this pattern of reduced RMR during the inactive phase. The inactive-phase RMR within thermal neutrality of the pregnant female was not different from that measured after the stillbirth, despite an almost 15% difference in body mass. During pregnancy, however, the female was more metabolically responsive to temperature below thermal neutrality, and had a lower upper critical temperature (i.e., was less tolerant of heat).     

Energy expenditure in Crocidurinae shrews (Insectivora): is metabolism a key component of the insular syndrome?

A cascade of morphological, ecological, demographical and behavioural changes operates within island communities compared to mainland. We tested whether metabolic rates change on islands. Using a closed circuit respirometer, we investigated resting metabolic rate (RMR) of three species of Crocidurinae shrews: Suncus etruscus, Crocidura russula, and C. suaveolens. For the latter, we compared energy expenditure of mainland and island populations. Our measurements agree with those previously reported for others Crocidurinae: the interspecific comparison (ANCOVA) demonstrated an allometric relation between energy requirements and body mass. Energy expenditure also scaled with temperature. Island populations (Corsica and Porquerolles) of C. suaveolens differed in size from mainland (gigantism). A GLM showed a significant relationship between energy expenditure, temperature, body mass and locality. Mass specific RMR allometrically scales body mass, but total RMR does not significantly differ between mainland and island, although island shrews are giant. Our results are consistent with other studies: that demonstrated that the evolution of mammalian metabolism on islands is partially independent of body mass. In relation to the insular syndrome, we discuss how island selective forces (changes in resource availability, decrease in competition and predation pressures) can operate in size and physiological adjustments.     

Resting Metabolic Rate in Severely Obese Diabetic and Nondiabetic Subjects

Objectives : To compare the resting metabolic rate (RMR) between diabetic and nondiabetic obese subjects and to develop a predictive equation of RMR for these subjects. Research Methods and Procedures : Obese adults (1088; mean age = 44.9 ± 12.7 years) with BMI ≥ 35 kg/m² (mean BMI = 46.4 ± 8.4 kg/m²) were recruited. One hundred forty‐two subjects (61 men, 81 women) were diagnosed with type 2 diabetes (DM), giving the prevalence of DM in this clinic population as 13.7%. RMR was measured by indirect calorimetry, and several multivariate linear regression models were performed using age, gender, weight, height, BMI, fat mass, fat mass percentage, and fat‐free mass as independent variables. Results : The severely obese patients with DM had consistently higher RMR after adjustment for all other variables. The best predictive equation for the severely obese was RMR = 71.767 ? 2.337 × age + 257.293 × gender (women = 0 and men = 1) + 9.996 × weight (in kilograms) + 4.132 × height (in centimeters) + 145.959 × DM (nondiabetic = 0 and diabetic = 1). The age, weight, and height‐adjusted least square means of RMR between diabetic and nondiabetic groups were significantly different in both genders. Discussion : Severely obese patients with type 2 diabetes had higher RMR than those without diabetes. The RMR of severely obese subjects was best predicted by an equation using age, gender, weight, height, and DM as variables.     

Physical activity in aging: comparison among young, aged, and nonagenarian individuals.

Physical activity (PA) is known to decline with age; however, there is a paucity of data on activity in persons who are in their nineties and beyond. We used objective and reliable methods to measure PA in nonagenarians (>or=90 yr; n=98) and hypothesized that activity would be similar to that of aged (60-74 yr; n=58) subjects but less than in young (20-34 yr; n=53) volunteers. Total energy expenditure (TEE) was measured by doubly labeled water over 14 days and resting metabolic rate (RMR) by indirect calorimetry. Measures of PA included activity energy expenditure adjusted for body composition, TEE adjusted for RMR, physical activity level (PAL), and activity over 14 days by accelerometry expressed as average daily durations of light and moderate activity. RMR and TEE were lower with increasing age group (P<0.01); however, RMR was not different between aged and nonagenarian subjects after adjusting for fat-free mass, fat mass, and sex. Nonagenarians had a lower PAL and were more sedentary than the aged and young groups (P<0.01); however, the nonagenarians who were more active on a daily basis walked further during a timed test, indicating higher physical functionality. For all measures of activity, no differences were found between young and aged volunteers. PA was markedly lower in nonagenarians compared with young and aged adults. Interestingly, PA was similar between young volunteers and those who were in their 60s and 70s, likely due to the sedentary nature of our society, particularly in young adults.     

Lower body mass and higher metabolic rate enhance winter survival in root voles,Microtus oeconomus

Although the biological significance of individual variation in physiological traits is widely recognized, studies of their association with fitness in wild populations are surprisingly scarce. We investigated the effect of individual phenotypic variation in body mass, resting (RMR) and peak metabolic rates (PMR) on mortality of the root vole Microtus oeconomus. Body mass and metabolic rates varied significantly among consecutive years and were also age dependent, as individuals born in late summer and autumn were characterized by significantly lower body mass and metabolic rates than animals born earlier. At the beginning of winter voles born in spring and early summer exhibited reduced body mass and metabolic rates, whereas animals born later maintained lower body mass and RMR, which may be interpreted as phenotypic plasticity enhancing the probability of survival. Body mass had no significant effect on vole survival during summer. In contrast, smaller individuals were characterized by lower mortality during early winter, whereas higher body mass was positively associated with survival later in the season. High body‐mass‐corrected RMR positively affected survival in both summer and winter. The effect of PMR was apparent only during winter, though its direction (and correlation with RMR) varied among years. Deep snow cover negatively affected the survival of voles in both early and late winter. Ambient temperature was positively associated with winter survival, except for late winter, when rising temperature caused flooding of vole habitat. We conclude that the lack of consistency in the directionality and strength of the effects of body mass and metabolic rates on winter survival does not undermine their importance, but rather demonstrates the ability of individuals to adjust metabolic rate to changing environmental conditions. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 297–309.