Resting Metabolic Rate Measurements Research Articles

Longitudinal Changes in Resting Metabolic Rates with Aging Are Accelerated by Diseases.

Resting metabolic rate (RMR) declines with aging and is related to changes in health status, but how specific health impairments impact basal metabolism over time has been largely unexplored. We analyzed the association of RMR with 15 common age-related chronic diseases for up to 13 years of follow-up in a population of 997 participants to the Baltimore Longitudinal Study of Aging. At each visit, participants underwent measurements of RMR by indirect calorimetry and body composition by DEXA. Linear regression models and linear mixed effect models were used to test cross-sectional and longitudinal associations of RMR and changes in disease status. Cancer and diabetes were associated with higher RMR at baseline. Independent of covariates, prevalent COPD and cancer, as well as incident diabetes, heart failure, and CKD were associated with a steeper decline in RMR over time. Chronic diseases seem to have a two-phase association with RMR. Initially, RMR may increase because of the high cost of resiliency homeostatic mechanisms. However, as the reserve capacity becomes exhausted, a catabolic cascade becomes unavoidable, resulting in loss of total and metabolically active mass and consequent RMR decline.

척수손상 장애인 대상 휴식기 신진대사량과 휠체어 주행속도별 신진대사 해당치 측정 연구

척수손상 장애인 대상 휴식기 신진대사량과 휠체어 주행속도별 신진대사 해당치 측정 연구

Resting metabolic rate and skeletal muscle SERCA and Na+ /K+ ATPase activities are not affected by fish oil supplementation in healthy older adults.

Omega‐3 polyunsaturated fatty acids (PUFAs) have unique properties purported to influence several aspects of metabolism, including energy expenditure and protein function. Supplementing with n‐3 PUFAs may increase whole‐body resting metabolic rate (RMR), by enhancing Na+/K+ ATPase (NKA) activity and reducing the efficiency of sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA) activity by inducing a Ca2+ leak‐pump cycle. The purpose of this study was to examine the effects of fish oil (FO) on RMR, substrate oxidation, and skeletal muscle SERCA and NKA pump function in healthy older individuals. Subjects (n = 16 females; n = 8 males; 65 ± 1 years) were randomly assigned into groups supplemented with either olive oil (OO) (5 g/day) or FO (5 g/day) containing 2 g/day eicosapentaenoic acid and 1 g/day docosahexaenoic acid for 12 weeks. Participants visited the laboratory for RMR and substrate oxidation measurements after an overnight fast at weeks 0 and 12. Skeletal muscle biopsies were taken during weeks 0 and 12 for analysis of NKA and SERCA function and protein content. There was a main effect of time with decrease in RMR (5%) and fat oxidation (18%) in both the supplementation groups. The kinetic parameters of SERCA and NKA maximal activity, as well as the expression of SR and NKA proteins, were not affected after OO and FO supplementation. In conclusion, these results suggest that FO supplementation is not effective in altering RMR, substrate oxidation, and skeletal muscle SERCA and NKA protein levels and activities, in healthy older men and women.

Limited mass-independent individual variation in resting metabolic rate in a wild population of snow voles (Chionomys nivalis).

Resting metabolic rate (RMR) is a potentially important axis of physiological adaptation to the thermal environment. However, our understanding of the causes and consequences of individual variation in RMR in the wild is hampered by a lack of data, as well as analytical challenges. RMR measurements in the wild are generally characterized by large measurement errors and a strong dependency on mass. The latter is problematic when assessing the ability of RMR to evolve independently of mass. Mixed models provide a powerful and flexible tool to tackle these challenges, but they have rarely been used to estimate repeatability of mass-independent RMR from field data. We used respirometry to obtain repeated measurements of RMR in a long-term study population of snow voles (Chionomys nivalis) inhabiting an environment subject to large circadian and seasonal fluctuations in temperature. Using both uni- and bivariate mixed models, we quantify individual repeatability in RMR and decompose repeatability into mass-dependent and mass-independent components, while accounting for measurement error. RMR varies among individuals, that is, is repeatable (R=.46) and strongly co-varies with BM. Indeed, much of the repeatability of RMR is attributable to individual variation in BM, and the repeatability of mass-independent RMR is reduced by 41% to R=.27. These empirical results suggest that the evolutionary potential of RMR independent of mass may be severely constrained. This study illustrates how to leverage bivariate mixed models to model field data for metabolic traits, correct for measurement error and decompose the relative importance of mass-dependent and mass-independent physiological variation.

Effects of heated water-based versus land-based exercise training on vascular function in individuals with peripheral artery disease.

Peripheral artery disease (PAD) is an atherosclerotic disease that is associated with poor vascular function, walking impairment, and reduced quality of life. Land-based exercise therapy (LBET) is frequently recommended to improve walking and reduce symptoms. Recently, evidence has suggested that heated-water exercise therapy (HWET) is an effective intervention for PAD. However, the efficacy of LBET versus HWET in PAD patients had not been elucidated. Therefore, we sought to compare effects of LBET with HWET on cardiovascular function, exercise tolerance, physical function, and body composition in PAD patients. PAD patients (n = 53) were recruited and randomly assigned to a LBET group (n = 25) or HWET group (n = 28). The LBET group performed treadmill walking, whereas the HWET group performed walking in heated water for 12 wk. Leg (legPWV) and brachial-to-ankle arterial stiffness (baPWV), blood pressure (BP), ankle-brachial index (ABI), 6-min walking distance (6MWD), claudication onset time (COT), physical function, and body composition were assessed before and after 12 wk. There were significant group-by-time interactions (P < 0.05) for legPWV, BP, 6MWD, COT, body composition, and resting metabolic rate (RMR). Both groups significantly reduced (P < 0.05) legPWV, BP, and body fat percentage, and HWET measures were significantly lower than LBET measures. Both groups significantly increased 6MWD, COT, and RMR, and HWET group measures were significantly greater than LBET measures. A time effect was noted for baPWV reduction in both groups (P < 0.05). These results suggest that both LBET and HWET improve cardiovascular function, exercise tolerance, and body composition, and HWET showed considerably greater improvements compared with LBET in patients with PAD.NEW & NOTEWORTHY The results of this study reveal for the first time that although land-based exercise therapy is effective for reducing arterial stiffness and blood pressure in patients with peripheral artery disease (PAD), heated-water exercise therapy demonstrates greater benefits on vascular function. The greater improvements in muscular strength, time to onset of claudication, and exercise tolerance after heated-water exercise therapy may have clinical implications for improving quality of life in patients with PAD. The heated-water exercise therapy intervention demonstrated relatively higher exercise training adherence (∼88%) compared with the land-based exercise intervention (∼81%).

Daily Changes of Resting Metabolic Rate in Elite Rugby Union Players

Preparation for competitive contact sport has been extensively researched. There are, however, limited data to guide players as to how the demands of their sport affect the energy requirements of recovery. We aimed to provide novel data on changes in resting metabolic rate (RMR) in contact sport athletes and relate these to the physical demands of training and competition. Twenty-two elite professional Premiership Rugby Union players were recruited to the study. Indirect calorimetry (Vyntus CPX canopy; CareFusion) was used to measure RMR each morning of the competitive game week, in a fasted, rested state. External loads for training and game play were monitored and recorded using global positioning systems (Catapult Innovations, Australia), whereas internal loads were tracked using rate of perceived exertion scales. Collisions were reviewed and recorded by expert video analysts for contacts in general play (breakdown and tackle area) or the set piece (scrum or maul). There were significant (P = 0.005) mean increases in RMR of approximately 231 kcal the morning after (game day [GD] + 1) and 3 d after the game (GD + 3), compared with the day before the game (GD - 1). The players were exposed to internal and external loads during the training week comparable to that of a match day; however, despite the equivocal loads between training and game play, there were no significant increases in RMR after training. The collisions experienced in rugby match play are likely to be responsible for the significant increases in RMR at GD + 1 and GD + 3. Consequently, the measurement of RMR via indirect calorimetry may provide a novel noninvasive measure of the effects of collisions. This study provides a novel insight to the energy requirements of recovering from contact sport.

Effects of core temperature, skin temperature, and inter-beat interval on resting metabolic rate measurements in thermoneutral conditions.

It is important to identify potential underlying factors that can affect the variability of resting metabolic rate (RMR) measurements. The RMRs of 20 college-aged men were tested twice in stable environmental conditions, with each measurement separated by 40 min. Skin temperature, core temperature, and inter-beat interval were monitored throughout the study as identified factors that could affect RMR measurements. Since environmental conditions in a clinic or laboratory can vary, skin temperature and core temperature can be affected which may affect RMR. Similarly, prior physical activity, stress, sleep, and caffeine intake can affect inter-beat interval and may be a co-variable affecting RMR. Higher RMR measurements were compared to lower RMR measurements. RMR for the higher trial was 2068 ± 66 kcal/day, the lower trial was 1975 ± 65 kcal/day (t = 4.23; p < 0.01). Core temperature for higher trial was 37.1 ± 0.1 °C, the lower trial was 36.8 ± 0.1 °C (s = 105.00; p < 0.01). Skin temperature measurements were significantly different for the anterior bicep site (t = -2.52; p = 0.02), but not for any other site. Inter-beat interval for the higher measurement was 1038 ± 33 ms, the lower measurement was 998 ± 32 ms (t = 3.82; p < 0.01). However, regression analysis found that none of the variables were significant predictors for the higher RMR, lower RMR, or change in RMR. While the factors affecting RMR measurement variability remain unclear, the results suggest that typical fluctuations in core temperature, skin temperature, and inter-beat interval do not effectively predict changes in RMR in a thermoneutral environment.

Accuracy of Predictive Resting-Metabolic-Rate Equations in Chinese Mainland Adults.

Accurate measurement of the resting metabolic rate (RMR) is necessary when we make energy requirements and nutrition suggestions in clinical. However, indirect calorimetry is not always available. The objectives of this study were to make a comparison between RMR measured by indirect calorimetry and RMR predicted by different kinds of equations, and to develop new predictive equations for Chinese mainland adults. In this study, 315 Chinese mainland adults from different provinces all over China were recruited. Subjects underwent half a day of testing, which consisted of anthropometric assessment and RMR measurement. Measured and predicted RMR were compared; new optimal equations for Chinese mainland adults were developed and tested by splitting the subjects into a development and validation group. The measured RMR was in the range of 831–2776 kcal/day (mean 1651 ± 339 kcal/day). Our findings indicated that, except for the Harris–Benedict and Schofield equations, three Chinese equations and two fat-free mass (FFM) modeling equations all significantly underestimated RMR compared to the measured value (all p < 0.01). There were no significant differences between predicted and measured RMR using the new equations for females and males. Of the pre-existing equations, Schofield’s is the most suitable for Chinese mainland adults. However, the two new equations developed in this study seem to be more effective for predicting the RMR of Chinese mainland adults, and need to be validated by a larger independent sample with different physiological and anthropometric characteristics.

Potential Benefit of Repeated Resting Metabolic Rate Measurements

Potential Benefit of Repeated Resting Metabolic Rate Measurements

Estimated Resting Metabolic Rate and Body Composition Measures Are Strongly Associated With Diabetic Retinopathy in Indonesian Adults With Type 2 Diabetes.

To investigate the associations of estimated resting metabolic rate (RMR), body fat (BF), subcutaneous fat (SCF), visceral fat (VF), fat-free mass (FFM) percentage, BMI, and waist circumference (WC) with diabetic retinopathy (DR) in Indonesian adults with type 2 diabetes. This was a community-based cross-sectional study of 1,184 subjects with type 2 diabetes. DR was assessed from fundus photography and categorized as mild, moderate nonproliferative DR (NPDR), and vision-threatening DR (VTDR). RMR and body composition parameters were measured using automated body composition scan. Logistic regression with semipartial correlation analysis was used. DR and VTDR were present in 43.1 and 26.3% of participants, respectively. After adjustment for age, sex, diabetes duration, fasting glucose, systolic blood pressure, smoking, diabetic ulcer, and use of combined diabetes treatment, per SD increase in RMR (odds ratio [OR] 2.60 [95% CI 2.19-3.07]; P < 0.001) was associated with DR, while per SD increases in BF (0.66 [95% CI 0.56-0.78]; P < 0.001), FFM (0.69 [0.57-0.84]; P < 0.001), VF (0.77 [0.67-0.88]; P < 0.001), BMI (0.83 [0.73-0.94]; P = 0.004), and WC (0.81 [0.73-0.91]; P < 0.001) were inversely associated with presence of DR. Similar associations were found for VTDR. Among all variables, RMR had the largest contribution to the variance in the DR model (39%). In this study, RMR and body composition measures were strongly associated with and contributed considerably to the presence and severity of DR. These findings, if confirmed, suggest that RMR and body composition may be strong markers that represent actual metabolic state in the pathophysiology of DR.

Impact of Feeding on Resting Metabolic Rate and Gas Exchange in Critically Ill Patients.

Feeding is understood to alter gas exchange and resting metabolic rate (RMR) in critically ill patients, but there are limited data describing such changes. A large collection of RMR measurements and energy intake was assembled in mechanically ventilated and critically ill patients. The data were used to explore differences in RMR, respiratory quotient (RQ), and carbon dioxide production (V̇co2 ) related to feeding state. A total of 708 RMR measurements were available. No significant thermogenic effect of feeding could be appreciated. When controlled for body weight, the difference was 4.2% (1946±400kcal/d for unfed vs 2028±341kcal/d for fed patients; P=.299), and this small difference was fully eliminated when body temperature was also controlled for. RQ increased as carbohydrate and energy intake increased, but there was much variation in the relationship. Among 215 overfed patients, only 22 had RQ ≥1.0, and among 9 patients whose carbohydrate intake alone exceeded RMR, only 4 had an RQ ≥1.0. V̇co2 was influenced mainly by the volume of oxygen consumed and to a lesser degree by carbohydrate intake. No appreciable thermogenic effect of feeding occurs in continuously fed critically ill patients. This factor does not need to be considered in the assessment of resting energy needs. RQ is not a reliable indicator of overfeeding, and the ability of carbohydrate intake to alter V̇co2 is small, although not absent.

Accuracy of Resting Metabolic Rate Prediction Equations in Athletes.

Jagim, AR, Camic, CL, Kisiolek, J, Luedke, J, Erickson, J, Jones, MT, and Oliver, JM. Accuracy of resting metabolic rate prediction equations in athletes. J Strength Cond Res 32(7): 1875-1881, 2018-The purpose of this study was to determine the accuracy of 5 different resting metabolic rate (RMR) prediction equations in male and female athletes. Twenty-two female (19.7 ± 1.4 years; 166.2 ± 5.5 cm; 63.5 ± 7.3 kg; 49.2 ± 4.3 kg of fat-free mass (FFM); 23.4 ± 4.4 body fat (BF) percent) and 28 male (20.2 ± 1.6 years; 181.9 ± 6.1 cm; 94.5 ± 16.2 kg; 79.1 ± 7.2 kg of FFM; 15.1 ± 8.5% BF) athletes were recruited to participate in 1 day of metabolic testing. Assessments comprised RMR measurements using indirect calorimetry, and body composition analyses using air displacement plethysmography. One-way repeated-measures analysis of variance with follow-up paired t tests were selected to determine differences between indirect calorimetry and 5 RMR prediction equations. Linear regression analysis was used to assess the accuracy of each RMR prediction method. An alpha level of p ≤ 0.05 was used to determine statistical significance. All the prediction equations significantly underestimated RMR while the Cunningham equation had the smallest mean difference (-165 kcals). In men, the Harris-Benedict equation was found to be the best prediction formula with the lowest root-mean-square prediction error value of 284 kcals. In women, the Cunningham equation was found to be the best prediction equation with the lowest root-mean-squared error value of 110 kcals. Resting metabolic rate prediction equations consistently seem to underestimate RMR in male and female athletes. The Harris-Benedict equation seems to be most accurate for male athletes, whereas the Cunningham equation may be better suited for female athletes.

The Effects Of An Acute Bout Of Resistance Training On College-aged Male 24hr Rmr

It has been demonstrated that increasing caloric expenditure through exercise participation is one mechanism by which to modify caloric balance in favor of weight loss. While chronic resistance training (RT) has been demonstrated to elevate resting metabolic rate (RMR) due to increased lean mass, there has been less research on the acute effects of a single bout of resistance training on RMR. PURPOSE: To determine the effects of an acute bout of resistance training on the 24 h RMR of college-aged males. METHODS: Ten healthy men aged 18-24yr performed 8 exercises (2 sets, 10 repetitions, 2 min recovery, 70% 1RM & 8RM) following ACSM Guidelines for RT. Subjects reported for testing following a 12 h fast and engaged in 7, 30 min RMR measurements over the next 24 h. Subjects completed both an experimental (RT) and control (no exercise) day separated by 1 week. RESULTS: RMR (kcal) data was analyzed using a 1 way ANOVA with repeated measures on 2 factors (group and time). Statistical analysis revealed that there was no significant main effect for group (2179.58± 44.82 kcal vs. 2143.16 ± 44.82 kcal; F = .330, p = .567) or group x time interaction (F =.592, p =.736, Table 1). There was a significant main effect for time (F = 5.126, p < .001, Table 2). CONCLUSION: We conclude that an acute bout of RT, following ACSM guidelines, did not significantly impact RMR in RT males 24 hrs post-exercise.Table 1: Mean 24-hour RMR Values by GroupTable 2: Mean RMR Values across Measurements

Biological and psychological mediators of the relationships between fat mass, fat-free mass and energy intake.

While recent studies in humansindicate that fat-free mass (FFM) is closely associated with energy intake (EI) when in energy balance, associations between fat mass (FM) and EI are inconsistent. The present study used a cross-sectional design to examine the indirect and direct effects of FFM, FM and resting metabolic rate (RMR) on EI in individuals at or close to energy balance. Data for 242 individuals (114 males; 128 females; BMI = 25.7 ± 4.9 kg/m2) were collated from the non-intervention baseline conditions of five studies employing common measures of body composition (air-displacement plethysmography), RMR (indirect calorimetry) and psychometric measures of eating behaviours (Dutch Eating Behaviour Questionnaire). Daily EI (weighed dietary records) and energy expenditure (flex heart rate) were measured for 6-7 days. Sub-analyses were conducted in 71 individuals who had additional measures of body composition (dual-energy X-ray absorptiometry) and fasting glucose, insulin and leptin. After adjusting for age, sex and study, linear regression and mediation analyses indicated that the effect of FFM on EI was mediated by RMR (P < 0.05). FM also independently predicted EI, with path analysis indicating a positive indirect association (mediated by RMR; P < 0.05), and a stronger direct negative association (P < 0.05). Leptin, insulin and insulin resistance failed to predict EI, but cognitive restraint was a determinant of EI and partially mediated the association between FM and EI (P < 0.05). While the association between FFM and EI was mediated by RMR, FM influenced EI via two separate and opposing pathways; an indirect 'excitatory' effect (again, mediated by RMR), and a stronger direct 'inhibitory' effect. Psychological factors such as cognitive restraint remain robust predictors of EI when considered alongside physiological determinants of EI, and indeed, have the potential to play a mediating role in the overall expression of EI.

Food Availability Is the Main Driver of Seasonal Changes in Resting Metabolic Rate in African Striped Mice (Rhabdomys pumilio).

Resting metabolic rate (RMR) influences energy allocation to survival, growth, and reproduction, and significant seasonal changes in RMR have been reported. According to one hypothesis, seasonal changes in RMR are mainly attributable to seasonal changes in ambient temperature (Ta) and food availability. Studies on species from the temperate zone indicated that food availability is the main driver. However, whether this is generally true is unknown, because studies from the tropics and subtropics, where most species live, are rare. We studied the African striped mouse (Rhabdomys pumilio) inhabiting a seasonal environment with hot dry seasons with low food availability and cold moist seasons with high food availability. Using 603 RMR measurements of 277 individuals, we investigated the relative importance of food availability and Ta on RMR during selected periods, in which one extrinsic factor varied while the other factor was relatively constant. At similar Ta, residual RMR increased with increasing levels of food availability. In contrast, different Ta did not influence residual RMR at similar levels of food availability. Thus, our study on a subtropical species gives support to the hypothesis, derived from temperate zone species, that food availability mainly drives seasonal changes in RMR.

Within-Day Energy Deficiency and Metabolic Perturbation in Male Endurance Athletes.

Endurance athletes are at increased risk of relative energy deficiency associated with metabolic perturbation and impaired health. We aimed to estimate and compare within-day energy balance in male athletes with suppressed and normal resting metabolic rate (RMR) and explore whether within-day energy deficiency is associated with endocrine markers of energy deficiency. A total of 31 male cyclists, triathletes, and long-distance runners recruited from regional competitive sports clubs were included. The protocol comprised measurements of RMR by ventilated hood and energy intake and energy expenditure to predict RMRratio (measured RMR/predicted RMR), energy availability, 24-hr energy balance and within-day energy balance in 1-hr intervals, assessment of body composition by dual-energy X-ray absorptiometry, and blood plasma analysis. Subjects were categorized as having suppressed (RMRratio < 0.90, n = 20) or normal (RMRratio > 0.90, n = 11) RMR. Despite there being no observed differences in 24-hr energy balance or energy availability between the groups, subjects with suppressed RMR spent more time in an energy deficit exceeding 400kcal (20.9 [18.8-21.8]hr vs. 10.8 [2.5-16.4], p = .023) and had larger single-hour energy deficits compared with subjects with normal RMR (3,265 ± 1,963kcal vs. -1,340 ± 2,439, p = .023). Larger single-hour energy deficits were associated with higher cortisol levels (r = -.499, p = .004) and a lower testosterone:cortisol ratio (r = .431, p = .015), but no associations with triiodothyronine or fasting blood glucose were observed. In conclusion, within-day energy deficiency was associated with suppressed RMR and catabolic markers in male endurance athletes.

Within-day energy deficiency and reproductive function in female endurance athletes.

We aimed to estimate and compare within-day energy balance (WDEB) in athletes with eumenorrhea and menstrual dysfunction (MD) with similar 24-hour energy availability/energy balance (EA/EB). Furthermore, to investigate whether within-day energy deficiency is associated with resting metabolic rate (RMR), body composition, S-cortisol, estradiol, T3 , and fasting blood glucose. We reanalyzed 7-day dietary intake and energy expenditure data in 25 elite endurance athletes with eumenorrhea (n=10) and MD (n=15) from a group of 45 subjects where those with disordered eating behaviors (n=11), MD not related to low EA (n=5), and low dietary record validity (n=4) had been excluded. Besides gynecological examination and disordered eating evaluation, the protocol included RMR measurement; assessment of body composition by dual-energy X-ray absorptiometry, blood plasma analysis, and calculation of WDEB in 1-hour intervals. Subjects with MD spent more hours in a catabolic state compared to eumenorrheic athletes; WDEB<0kcal: 23.0hour (20.8-23.4) vs 21.1hour (4.7-22.3), P=.048; WDEB<-300kcal: 21.8hour (17.8-22.4) vs 17.6hour (3.9-20.9), P=.043, although similar 24-hour EA: 35.6 (11.6) vs 41.3 (12.7) kcal/kg FFM/d, (P=.269), and EB: -659 (551) vs -313 (596) kcal/d, (P=.160). Hours with WDEB <0kcal and <-300kcal were inversely associated with RMRratio (r=-.487, P=.013, r=-.472, P=.018), and estradiol (r=-.433, P=.034, r=-.516, P=.009), and positively associated with cortisol (r=.442, P=.027, r=.463, P=.019). In conclusion, although similar 24-hour EA/EB, the reanalysis revealed that MD athletes spent more time in a catabolic state compared to eumenorrheic athletes. Within-day energy deficiency was associated with clinical markers of metabolic disturbances.

Investigating predictors of eating: is resting metabolic rate really the strongest proxy of energy intake?

Background: Evidence suggests that fat-free mass and resting metabolic rate (RMR), but not fat mass, are strong predictors of energy intake (EI). However, body composition and RMR do not explain the entire variance in EI, suggesting that other factors may contribute to this variance.Objective: We aimed to investigate the associations between body mass index (in kg/m2), fat mass, fat-free mass, and RMR with acute (1 meal) and daily (24-h) EI and between fasting appetite ratings and certain eating behavior traits with daily EI. We also evaluated whether RMR is a predictor of the error variance in acute and daily EI.Design: Data collected during the control condition of 7 studies conducted in Ottawa, Ontario, Canada, were included in these analyses (n = 191 and 55 for acute and daily EI, respectively). These data include RMR (indirect calorimetry), body composition (dual-energy X-ray absorptiometry), fasting appetite ratings (visual analog scales), eating behavior traits (Three-Factor Eating Questionnaire), and EI (food buffet or menu).Results: Fat-free mass was the best predictor of acute EI (R2 = 0.46; P < 0.0001). The combination of fasting prospective food consumption ratings and RMR was the best predictor of daily EI (R2 = 0.44; P < 0.0001). RMR was a statistically significant positive predictor of the error variance for acute (R2 = 0.20; P < 0.0001) and daily (R2 = 0.23; P < 0.0001) EI. RMR did, however, remain a statistically significant predictor of acute (R2 = 0.32; P < 0.0001) and daily (R2 = 0.30; P < 0.0001) EI after controlling for this error variance.Conclusions: Our findings suggest that combined measurements of appetite ratings and RMR could be used to estimate EI in weight-stable individuals. However, greater error variance in acute and daily EI with increasing RMR values was observed. Future studies are needed to identify whether greater fluctuations in daily EI over time occur with increasing RMR values. This trial was registered at clinicaltrials.gov as NCT02653378.

Abstract P469: CRISPR-Cas9 Gene Editing Yields Genetic Regulation of Obesity and Metabolism in Female LH-derived Rats

Despite strong evidence that the Metabolic Syndrome (MetS) and its defining features (central obesity, dyslipidemia, hypertension, hyperglycemia) are highly heritable, the genetic etiology is complex and relatively few causative genes are known. For this reason, we employ the Lyon Hypertensive (LH) rat, a well-characterized genetic model of MetS. Previously, we identified a novel gene ( RGD1562963 ) on LH rat chromosome 17 (RNO17) that affects components of MetS, using a combination of genetic mapping and gene network analyses. In this study, frameshift mutations (by CRISPR-Cas9) in exon 2 of RGD1562963 is shown to change resting metabolic rate (RMR) and body composition in LH-derived female rats, measured at 8 and 11 weeks of age, despite no differences in either total body weight or food consumption. RGD1562963 -/- ( RGD -/- ) females have significantly more body fat mass than their wild-type control at 8 weeks of age, measured by nuclear magnetic resonance (NMR) as a percentage of total body weight ( # 8 weeks: WT = 5.08±0.099, n=5; RGD -/- = 6.52±0.260, n=8; *p&lt;.001), and this difference increases by 11 weeks of age (WT = 5.39±0.140, n=5; RGD -/- = 7.81±0.293, n=8, *p&lt;.0001). RMR measurements at 8 weeks showed that both genotypes had identical resting energy expenditure (WT: 0.721±0.033 kcal/hr, n=5; RGD -/- : 0.721±0.021 kcal/hr, n=6) and body weights (WT = 160.5g±6.884, n=5; RGD -/- = 160.7g±4.246, n=8). Though no body weight differences appear by 11 weeks (WT: 196.5g±7.226, n=5; RGD -/- : 196.1g±3.765, n=8), the wild-type females have an unexpected decrease in RMR, while the RMR of RGD -/- females remains high (WT: 0.654±0.005 kcal/hr, n=4; RGD -/- : 0.759±0.014 kcal/hr, n=7, *p&lt;.01). Our studies suggest RGD1562963 is an obesity susceptibility gene. Furthermore, inhibition of this gene at the whole body level is tolerated, and unexpectedly induced increased resting metabolic rate despite increased adiposity, possibly as a protective mechanism. The continued study of this rat model of Metabolic Syndrome has the potential to functionally validate an uncharacterized regulatory gene, and provide novel targets for pharmacological intervention in the treatment of obesity. # all measures are presented as mean±SEM, * RM 2-WAY ANOVA, Sidak’s correction

Reliability of resting metabolic rate measurements in young adults: Impact of methods for data analysis

A high inter-day reliability is a key factor to analyze the magnitude of change in resting metabolic rate (RMR) after an intervention, and the impact of using different methods for data analysis is not known. The aims of this study were: i) to analyze the impact of methods for data analysis on RMR and respiratory exchange ratio (RER) estimation; ii) to analyze the impact of methods for data analysis on inter-day RMR and RER reliability; iii) to compare inter-day RMR and RER reliability across methods for data analysis in participants who achieved steady state (SS) vs. participants who did not achieve SS. Seventeen young healthy adults completed two 30-min indirect calorimetry (IC) measures ontwo consecutive mornings, using two metabolic carts each day. Two methods for data analysis wereused: i) Selection of a predefined time interval (TI) every 5min (1-5min, 6-10min, 11-15min, 16-20min, 21-25min, 26-30min); and TI representing the whole measurement period (0-30min, 5-30min, 5-25min); and ii) Methods based on the selection of the most stable period (SSt methods) (3min SSt, 4min SSt, 5min SSt, 10min SSt). Additionally, participants were classified as those achieving SS (CV<10% for VO2, VCO2 and VE, and CV<5% for RER) and those who did not. RMR and RER measurements were lower when following SSt methods than when following TI methods (all P<0.01). Although no significant differences were found between different lengths of SSt, 5min SSt presented the lowest RMR. There were no differences on the inter-day reliability across methods for data analysis (TI and SSt) (all P>0.2), and there was no systematic bias when comparing RMR and RER day 1 and day 2 measurements (all P>0.1). Inter-day reliability was similar in individuals who achieved the SS and individuals who did not achieve it. The results were consistent independently of the metabolic cart used. The 5min SSt approach should be the method of choice for analyzing IC measures with metabolic carts. However, achieving SS should not be an inclusion criterion in an IC study with young healthy adults.