[Study of Basal metabolic rate of 81 young adults aged 20-29 years old in Changsha].

Objective: To determine the basal metabolic rate (BMR) of young adults aged between 20-29 years old in Changsha. Methods: We recruited volunteers to join in our research project from April to May, 2015. All recruited volunteers must meet the inclusion criteria: aged 20-29 years old, height between 164-180 centimeters in males and 154-167 centimeters in females, in good health condition, and with no habit of regular physical exercise in last year. Finally, 81 qualified volunteers were selected as research objects, including 43 males and 38 females. The BMR, resting lying metabolism rate and resting sitting metabolism rate of the subjects were detected, and the determined BMR was compared with the calculated results: from the adjusted Schofield equation. Results The BMR, resting lying metabolism rate and resting sitting metabolism rate among males were (166.10±22.09), (174.22±24.56), and (179.54±23.35) kJ·m(-2)·h(-1), respectively, which were all higher than those among females were (137.70±20.04), (149.79±19.25), and (167.78±26.02) kJ·m(-2)·h(-1), respectively, (P<0.001). The BMR of males and females calculated from the adjusted Schofield equation were (160.83±3.93), and (140.29±4.18) kJ·m(-2)·h(-1), respectively, and there was no significantly statistical difference found between the determined BMR and the calculated results from Schofield equation (adjusted) classified by sex, all P values >0.05. Conclusion: The BMR of young adults aged 20-29 years old in Changsha was in the national average level, and the adjusted Schofield equation displayed fine accuracy in predicting BMR of young adults aged 20-29 years old in Changsha.

Serum scEMC10 Levels are Negatively Associated With Resting Metabolic Rate and age in Humans.

CONTEXT: We have recently shown that the secreted isoform of endoplasmic reticulum membrane complex subunit 10 (scEMC10) is upregulated in human obesity and that overexpression of scEMC10 promotes, whereas antibody neutralization of circulating scEMC10 prevents diet-induced obesity in mice. OBJECTIVE: To explore associations of serum scEMC10 with body mass index (BMI), resting metabolism rate (RMR), and age in humans. DESIGN: A cross-sectional study. SETTING AND PATIENTS: A total of 833 participants from a Chinese physical examination cohort and 191 participants from the Leipzig Obesity Biobank cohort. MAIN OUTCOME MEASURES: Serum scEMC10 concentrations are measured using chemiluminescent immunoassay. RMR is calculated based on measurements from indirect calorimetry with an open-circuit ventilated-hood system. RESULTS: In the Chinese physical examination cohort, a J-shaped nonlinear correlation between BMI and serum scEMC10 was identified in participants where underweight, overweight, and obese people all presented higher serum scEMC10 levels than normal weight people. Participants younger than age 30 years old exhibited significantly higher serum scEMC10 levels than those older than 50 years of age. In addition, participants aged 30 to 40 years also had significantly higher serum scEMC10 levels than those aged 50 to 60 years. In the Leipzig Obesity Biobank cohort, we observed a significantly negative correlation between serum scEMC10 and resting energy expenditure after adjusting for BMI. Participants in the highest quartile of serum scEMC10 levels had significantly lower RMR than those in the first quartile. RMR had an independently inverse association with serum scEMC10. CONCLUSIONS: Serum scEMC10 levels are negatively associated with age and RMR in humans.

Modification of resting metabolism, body composition, and muscle strength after resolution of coronavirus disease 2019.

BACKGROUND & AIMS: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes changes that can influence human metabolism and modify the distribution of body compartments. We aimed to describe the clinical findings of changes in resting metabolism, muscle strength, and body composition in nonhospitalized patients after being diagnosed with coronavirus disease 2019 (COVID-19). METHODS: Physically active patients were evaluated at a nutrition clinic, and indirect calorimetry (IC) and body composition analysis using portable ultrasound were performed. After a routine appointment, all patients were instructed to inform the staff if they tested positive for SARS-CoV-2 infection. Our sample included individuals diagnosed with COVID-19, confirmed by real-time reverse transcription polymerase chain reaction (RT-PCR), within 7 days of the routine appointment. After an average incubation period of 14-21 days, in which there was no proven transmission of disease by RT-PCR, all of the patients were re-evaluated. RESULTS: A total of 38 volunteers (63.2% female) completed the study and were included in the analysis. The mean age of the participants was 37.3 ± 8.8 years. The comparison between pre- and post-COVID-19 stratified by sex demonstrated significant reduction in the RMR and RMR adjusted for weight (p < 0.0001) for both groups. Regarding body composition, there was a significant increase observed in fat mass in men (p < 0.002) and women (p < 0.01), and a significant reduction observed in fat-free mass (men: p < 0.002; women: p < 0.001) and skeletal muscle mass (men: p = 0.003; women: p < 0.0001). There was a significant difference between the change in the RMR measured by IC (p < 0.0001) and that calculated by the predictive equation of Cunningham (1980) (p < 0.0001), whereas the Harris and Benedict (1918) and Mifflin (1990) equations exhibited no difference. However, the mean difference in RMR between the post- and pre-COVID-19 calculated by the Cunningham equation was -40.4 kcal/day (95% confidence interval [CI]: -56.38 to -24.45), whereas the mean difference measured by IC was -362.3 kcal/day (95% CI: -452.7 to -271.9). CONCLUSION: This study describes the trends in the RMR, and body composition in individuals with COVID-19 who were not hospitalized from the pre-COVID-19 period to the post-COVID-19 period. A significant reduction in resting energy expenditure, and loss of fat-free mass and muscle mass in the post-COVID-19 period were observed in both men and women.

Body composition and energy expenditure in anorexia nervosa: preliminary data of outpatients with recovering and active disease.

BACKGROUND: In Anorexia Nervosa (AN) recovery, body mass index (BMI) may not reflect body composition. To investigate recovery, bioelectrical impedance (BIA) parameters and energy expenditure were investigated in patients with active and recovering AN, with emphasis on phase angle (PA), a BIA parameter. METHODS: BMI, PA, indirect BIA parameters (fat free mass, fat mass, total body water, fat free mass index, fat mass index) and resting metabolic rate (RMR) were obtained. Data from subjects distributed to active AN (ANact, n = 9), recovered AN (ANrec, n = 9) and healthy individuals (HI) (n = 16) were compared employing univariate methods and ordinal logistic regression. RESULTS: In univariate comparison, the BMI would not distinguish recovered individuals; this distinction was observed for the PA (p = < 0,001). PA showed a good capacity to discriminate, between ANrec and HI (AUC = 0.792; CI = 0.564- 1.000; p = 0.017). In 2 models of ordinal logistic regression PA (OR = 0.123; 95% CI 0.030; 0.503 and OR = 0.091; 95% CI 0.016; 0.528) remained as a significant independent variable, indicating that increases in PA are related to higher probabilities of moving from ANact, to ANrec and to HI group. Bivariate regression indicated the presence of a relationship between PA and (R2 = 0.266, p = 0.002). CONCLUSIONS: Changes in body composition and energy expenditure were observed in recovered anorexics with normal BMI. PA can play an important role in the assessment of recovering anorexic patients.

In recovery from anorexia nervosa, the body mass index does not reflect changes in body composition. Energy expenditure can change according to body composition in an anorexia nervosa and normal individuals. To investigate distinctive parameters in recovering Anorexia Nervosa patients, we evaluated body mass index and other indices obtained from body measurements by bioimpedance among patients with anorexia nervosa with low weight and in the weight recovery phase compared with a group of normal weight women without anorexia nervosa. In conclusion, we observed that one of these indexes, the phase angle can play an important role in the assessment of nutritional status in recovering anorexia nervosa.

Short-Term Ingestion of Medium-Chain Triglycerides Could Enhance Postprandial Consumption of Ingested Fat in Individuals with a Body Mass Index from 25 to Less than 30: A Randomized, Placebo-Controlled, Double-Blind Crossover Study.

The elimination of obesity is essential to maintaining good health. Medium-chain triglycerides (MCTs) inhibit fat accumulation. However, studies examining energy expenditure and fat oxidation with continuous ingestion of MCTs show little association with the elimination of obesity. In this study, we conducted a randomized, double-blind crossover clinical trial to investigate the effects of continuous ingestion of MCTs on postprandial energy expenditure and ingested long-chain triglycerides (LCTs) oxidation. A daily 2 g of MCTs were ingested for two weeks by sedentary participants with a body mass index (BMI) from 25 (kg/m2) to less than 30. Ingestion of a meal containing MCTs and isotopic carbon-13-labeled (13C) LCTs increased energy expenditure and consumption of diet-derived LCTs, as determined by postprandial 13C carbon dioxide excretion, compared to canola oil as the placebo control. These results indicate that continuous ingestion of MCTs could enhance postprandial degradation of diet-derived fat and energy expenditure in sedentary, overweight individuals.

Resting metabolic rate and its adjustments as predictors of risk protein-energy wasting in hemodialysis patients.

BACKGROUND: The purpose of the present study was to explore the association between resting metabolic rate (RMR) and protein-energy wasting (PEW) risk in Chinese hemodialysis patients by age and gender subgroup. METHODS: RMR and body composition (body cell mass (BCM) and fat mass) of 774 patients undergoing hemodialysis were estimated by bio-electrical impedance analysis (BIA). Anthropometric data were collected by a standard measurement protocol, and the upper arm muscle circumference (AMC) was calculated. Biochemical nutritional and dialysis parameters were obtained. Linear regression analysis was used to analyze the relationship among RMR, body composition and nutritional factors. RESULTS: The mean age was 54.96 ± 15.78 years. RMR level in patients was 1463.0 (1240.5, 1669.0) kcal/d. In multiple linear regression models, BCM, left calf circumference (LCC), fat mass were the determinants association with RMR (P<0.001). Among the patients in the sample, 133 (17.2%) had been diagnosed with PEW per International Society of Renal Nutrition and Metabolism (ISRNM) criteria and 363 (46.9%) were being at risk PEW. The area under the receiver-operating characteristic curve (AUC) of RMR for predicting risk PEW was greater than RMR/BCM and RMR/body surface area (BSA). When the cutoff of RMR was 1481 kcal/d it had the higher sensitivity and specificity (82 and 42%), and the AUC was 0.68 in elderly maintenance hemodialysis (MHD) patients (P<0.001). After adjustment for potential confounders, lowest RMR quartile level (<1239) increased the risk of PEW (OR = 4.71, 95% CI: 1.33-16.64, P=0.016) in all patients. CONCLUSIONS: Older patients with PEW have a lower RMR reduction. RMR and RMR/BCM may play the role in objective screening to detect risk PEW in MHD patients, especially in males.

Seasonal adaptations in energy budgeting in the primate Lepilemur leucopus.

The spiny forest of South Madagascar is one of the driest and most unpredictable habitats in Africa. The small-bodied, nocturnal primate Lepilemur leucopus lives in this harsh habitat with high diurnal and seasonal changes in ambient temperature. In this study, we investigated seasonal adaptions in energy budgeting of L. leucopus, which allow it to live under these conditions by measuring resting metabolic rate using open-flow respirometry. No signs of heterothermy were detected, and resting metabolic rate was significantly lower in the warmer wet season than in the colder dry season. In fact, L. leucopus possesses one of the lowest mass-specific metabolic rates measured so far for an endotherm, probably the result of adaptations to its habitat and folivorous and potentially toxic diet. Surprisingly, we identified a shift of the thermoneutral zone from between 25 and 30 °C in the wet season to between 29 and 32 °C in the cool dry season. L. leucopus seems to be more affected by the hot daytime temperatures during the dry season and thermoregulation seems to be more costly during this time, which makes this shift of the thermoneutral zone advantageous. Our findings suggest that L. leucopus has a very small scope to unfavorable conditions, making it highly vulnerable, e.g., to changing conditions due to climate change.

Effects of Acute Vaporized Nicotine in Non-Tobacco Users at Rest and during Exercise.

Smokers, and even non-smokers, may utilize vaporized nicotine delivered by electronic cigarette (EC) due to the perception that EC are "healthier" than traditional tobacco cigarettes. The effects of vaporized nicotine delivered by EC on resting blood pressure (BP) and resting metabolic rate (RMR), or BP and aerobic power during exercise have not been studied. This investigation tested the effects of acute vaporized nicotine inhalation by EC on resting BP and RMR and cycle exercise BP, metabolic responses, and aerobic power in young, normotensive non-smokers. Using a double-blind design, 20 subjects (10 female) participated in two randomized trials: placebo (0 mg nicotine) or nicotine (18 mg nicotine). Participants inhaled from EC once every 30 s for 10 min (20 inhalations total). RMR was assessed 40 min later by indirect calorimetry followed by an incremental cycle test. RMR was not different between trials (p=0.79). Compared to the placebo, resting diastolic pressure (DBP) was 3 mmHg higher with nicotine (p=0.04). VO2peak was not different between the nicotine trial (2.3±0.8 L•min-1) and placebo (2.3±0.7 L•min-1) trials (p=0.77), and Wmax was also similar between nicotine (201.0±53.8 W) and the placebo (204.8±57.8 W) (p=0.29). During the cycle exercise test, average DBP was higher following nicotine use compared with placebo trial (p=0.05), and exercise DBPpeak after nicotine (79.4±7.6) was significantly higher than placebo (74.9±8.3 mmHg) (p=0.02). Resting systolic blood pressure (SBP) was 3.7 mmHg lower for nicotine trial (p=0.04) but no SBP treatment effect was observed during exercise (p=0.14). Our results show that acute vaporized nicotine inhalation via EC increases resting and exercise DBP but does not affect RMR or cycle aerobic power in young, normotensive non-smokers.

Taxa metabólica de repouso de ciclistas estimada por equações e obtida por calorimetria indireta / Resting metabolic rate of cyclists estimated by mathematical equations and obtained by indirect calorimetry

A taxa metabólica de repouso (TMR) pode ser determinada por calorimetria indireta (CI). Porém, em função da praticidade, na prática clínica na maioria das vezes esta é estimada por equações de predição, as quais foram desenvolvidas em estudos envolvendo indivíduos não atletas. Apesar de alguns autores terem indicado que tais equações não estimam adequadamente a TMR, estas têm sido bastante utilizadas para calculá-la e prescrever dietas, inclusive para atletas. O objetivo deste estudo foi comparar a TMR determinada por CI com a estimada pelas equações de Harris & Benedict (HB), Schofield, FAO/WHO/UNU e Henry & Rees (HR), em 15 homens ciclistas, de 24,4 ± 3,68 anos, apresentando índice de massa corporal de 21,97 ± 1,46kg/m² e VO2máx de 70,00 ± 5,32mL(kg.min)-1. Para comparar a TMR determinada por CI e pelas equações, utilizou-se o tratamento estatístico testes t de Student (variáveis com distribuição normal) e de Mann-Whitney (variáveis sem distribuição normal), considerando p < 0,05. Além disso, foi realizada correlação de Pearson entre TMR e massa livre de gordura (MLG). Verificou-se que a TMR foi subestimada em 23,5 por cento, 16,7 por cento, 16,8 por cento e 16,9 por cento, respectivamente, quando se utilizaram as equações de HR, FAO/WHO/UNU, Schofield e HB, em relação à TMR obtida por CI. A TMR se correlacionou com a MLG (r = 0,551, p = 0,03). Os resultados confirmam que as equações avaliadas não são adequadas para estimar a TMR em atletas. Tais resultados podem ser explicados pela maior quantidade de MLG apresentada por atletas e possivelmente maior resposta dos receptores β-adrenérgicos aos estímulos do sistema nervoso simpático, resultando em TMR mais alta que em indivíduos sedentários. Diante disso, desenvolveu-se uma equação com as variáveis MLG e idade para melhor estimativa da TMR de ciclistas. Recomenda-se, no entanto, que a equação desenvolvida seja validada em estudo envolvendo um número maior de ciclistas, para que...

The resting metabolic rate (RMR) can be determined by indirect calorimetry (IC). However, the clinical estimation of this parameter has been done using mathematical equations, which were developed in studies involving non-athletes. Although some authors have indicated that such equations do not estimate correctly the RMR, they have been constantly used to estimate such parameter and to prescribe diets, including for athletes. The objective of this study was to compare the RMR determined by IC with the ones estimated using the equations proposed by Harris & Benedict (HB), Schofield, FAO/WHO/UNU and Henry & Rees (HR), in 15 male cyclists, aged 24.4±3.68 years, body mass index of 21.97±1.46 kg/m² and VO2max of 70.00±5.32 mL(kg.min)-1. Student's t test (when data presented normal distribution) and Mann-Whitney (when data did not present normal distribution) were used to compare the RMR determined by IC and the ones estimated by the equations. Probability values below 0.05 were considered statistically significant. Pearson bivariate correlation coefficients were calculated to evaluate the relationship between RMR and fat free mass (FFM). It was verified that the RMR was significantly underestimated in 23.5 percent, 16.7 percent, 16.8 percent and 16.9 percent, respectively by the equations proposed by HR, FAO/WHO/UNU, Schofield and HB in comparison to RMR obtained by IC. RMR values were significantly correlated with FFM (r=0.551, p=0.03). These results confirm that the equations evaluated in this study are not appropriate to estimate the RMR of athletes. Such results can be explained by the fact that athletes have more FFM and possibly a greater β- adrenergic receptors response to the sympathetic nervous system, which in turn leads to RMR higher than in sedentary people. Therefore, we created an equation considering the FFM and age variables to better estimate athletesï RMR. However, this equation should be validated in a study involving...

THE EVOLUTION OF ENDOTHERMY: TESTING THE AEROBIC CAPACITY MODEL.

One of the most important events in vertebrate evolution was the acquisition of endothermy, the ability to use metabolic heat production to elevate body temperature above environmental temperature. Several verbal models have been proposed to explain the selective factors leading to the evolution of endothermy. Of these, the aerobic capacity model has received the most attention in recent years. The aerobic capacity model postulates that selection acted mainly to increase maximal aerobic capacity (or associated behavioral abilities) and that elevated resting metabolic rate evolved as a correlated response. Here we evaluate the implicit evolutionary and genetic assumptions of the aerobic capacity model. In light of this evaluation, we assess the utility of phenotypic and genetic correlations for testing the aerobic capacity model. Collectively, the available intraspecific data for terrestrial vertebrates support the notion of a positive phenotypic correlation between resting and maximal rates of oxygen consumption within species. Interspecific analyses provide mixed support for this phenotypic correlation. We argue, however, that assessments of phenotypic or genetic correlations within species and evolutionary correlations among species (from comparative data) are of limited utility, because they may not be able to distinguish between the aerobic capacity model and plausible alternatives, such as selection acting directly on aspects of thermoregulatory abilities. We suggest six sources of information that may help shed light on the selective factors important during the evolution of high aerobic metabolic rates and, ultimately, the attainment of endothermy. Of particular interest will be attempts to determine, using a combination of mechanistic physiological and quantitative-genetic approaches, whether a positive genetic correlation between resting and maximal rates of oxygen consumption is an ineluctable feature of vertebrate physiology.