Postprandial resting metabolic rate and body composition in the moderately obese and normal-weight adult subjects at sitting posture

A reduced metabolic rate in the etiology of obesity has been a subject of controversy. The prediction of the energy requirements for the obese using reference values may therefore be distorted. In order to examine this possibility, resting metabolic rate (RMR) while the subject was sitting comfortably in a chair was measured in a total of 134 moderately obese and normal-weight subjects (68 women aged 20 to 71 with a mean of 53.1 and 66 men aged 20 to 63 with a mean of 36.5). RMR per kg of body weight was significantly lower in the female obese subjects, but not in the male obese subjects. There was no evidence of difference in RMR between obese and normal-weight subjects in either sex when RMR was indexed with fat-free mass (FFM), indicating no substantial decrease in the metabolism due to obesity. Multiple regression analyses indicate that standardization of RMR by FFM eliminates the apparent difference in RMR between the sexes, and the diminution of RMR with age was not observed. While the best and logical prediction of RMR is to use FFM, regression analyses suggest an alternative way of predicting RMR by an incorporation of subscapular skinfold thickness to adjust the different body composition in lean and obese subjects. Prediction equations of postprandial RMR (kcal/24-h) while sitting are RMR = 24.5 x FFM(kg) + 303.7, and RMR = 22.7 x weight(kg) - 13.6 x SSF (subscapular skinfold: mm) + 350.6. Problems in predicting RMR are discussed.     

Differences in resting metabolic rate between white and African-American young adults

OBJECTIVE: A reported lower resting metabolic rate (RMR) in African-American women than in white women could explain the higher prevalence of obesity in the former group. Little information is available on RMR in African-American men. RESEARCH METHODS AND PROCEDURES: We assessed RMR by indirect calorimetry and body composition by DXA in 395 adults ages 28 to 40 years (100 African-American men, 95 white men, 94 African-American women, and 106 white women), recruited from participants in the Coronary Artery Risk Development in Young Adults (CARDIA), Birmingham, Alabama, and Oakland, California, field centers. RESULTS: Using linear models, fat-free mass, fat mass, visceral fat, and age were significantly related to RMR, but the usual level of physical activity was not. After adjustment for these variables, mean RMR was significantly higher in whites (1665.07 +/- 10.78 kcal/d) than in African Americans (1585.05 +/- 11.02 kcal/d) by 80 +/- 16 kcal/d (p < 0.0001). The ethnic x gender interaction was not significant (p = 0.9512), indicating that the difference in RMR between African-American and white subjects was similar for men and women. DISCUSSION: RMR is approximately 5% higher in white than in African-American participants in CARDIA. The difference was the same for men and women and for lean and obese individuals. The prevalence of obesity is not higher in African-American men than in white men. Because of these reasons, we believe that RMR differences are unlikely to be a primary explanation for why African-American women are more prone to obesity than white women.     

Impact of indexing resting metabolic rate against fat-free mass determined by different body composition models

OBJECTIVE: To examine the differences arising from indexing resting metabolic rate (RMR) against fat-free mass (FFM) determined using two-, three- and four-compartment body composition models. DESIGN: All RMR and body composition measurements were conducted on the same day for each subject following compliance with premeasurement protocols. SUBJECTS: Data were generated from measurements on 104 males (age 32.1+/-12.1 y (mean+/-s.d.); body mass 81.15+/-12.85 kg; height 179.5+/-6.5 cm; body fat 20.6+/-7.6%). INTERVENTIONS: Body density (BD), total body water (TBW) and bone mineral mass (BMM) were measured by hydrodensitometry, deuterium dilution and dual energy X-ray absorptiometry (DXA), respectively. These measures were used to determine two (hydrodensitometry: BD; hydrometry: TBW)-, three (BD and TBW)- and four- compartment (BD, TBW and BMM) FFM values. DXA also provided three compartment derived FFM values. RMR was measured using open circuit indirect calorimetry. RESULTS: Three (body fat group: lean, moderate, high) x five (body composition determination: hydrodensitometry, hydrometry, three-compartment, DXA, four-compartment) ANOVAs were conducted on FFM and RMR kJ.kg FFM(-1).d(-1). Within-group comparisons revealed that hydrodensitometry and DXA were associated with significant (P<0.001) overestimations and underestimations of FFM and RMR kJ.kg FFM(-1).d(-1), respectively, compared with four-compartment-derived criterion values. A significant interaction (P<0.001) resulted from DXA's greater deviations from criterion values in lean subjects. While hydrometric means were not significantly (P> or =0.68) different from criterion values intraindividual differences were large (FFM: -1.5 to 2.9 kg; RMR: -6.0 to 3.2 kJ.kg FFM(-1).d(-1)). CONCLUSION: The relationship between RMR kJ.kg FFM(-1).d(-1) and exercise status would best be investigated using three (BD, TBW)- or four (BD, TBW, BMM)-compartment body composition models to determine FFM. Other models either significantly underestimate indexed RMR (hydrodensitometry, DXA) or display large intraindividual differences (hydrometry) compared with four-compartment derived criterion values. SPONSORSHIP: Australian Research Council (small grants scheme).     

Changes in body weight, body composition and resting metabolic rate (RMR) in first-year university freshmen students

OBJECTIVES: The purpose of the present study was to document any changes that might occur in body weight, body composition, RMR, and dietary intake in newly enrolled college freshmen. METHODS: Body weight, RMR by ventilated O(2) consumption, body composition by bioelectrical impedance and dietary intakes were recorded in 27 first-year college freshmen during their initial 16-week semester. RESULTS: Mean body weight increased significantly with time (3.0 lbs; p < 0.001); 16 subjects (59%) gained >or= 3.0 lbs, while 6 subjects (22%) gained >or= 6 lbs. Percent fat mass significantly increased (p < 0.001), while lean body mass decreased (p < 0.001). Changes in RMR failed to reach statistical significance; however, there was a significant correlation between changes in weight and RMR (r = 0.45; p < 0.02). Mean reported calorie intake did not differ significantly between the beginning (1905 +/- 664 kcal) and end (1960 +/- 687 kcal) of the study. However, the differences ( approximately 55 kcal) are in the range necessary to support the mean 3 lb. weight gain. CONCLUSIONS: The present study supports the notion that freshmen students, on average, gain weight during their first semester; however, this weight gain may be more modest than generally perceived. The study also provides important new data on changes in diet, body composition and RMR.     

Meta-analysis of resting metabolic rate in formerly obese subjects.

BACKGROUND: A low resting metabolic rate (RMR) for a given body size and composition is partly genetically determined and has been suggested to be a risk factor for weight gain. Moreover, a low relative RMR has been reported in some, but not all, studies of formerly obese persons. The inconsistent reports may be due to a lack of statistical power to detect small differences in RMR and improper adjustment for body size and composition. OBJECTIVE: We conducted a meta-analysis based on published studies of RMR in formerly obese persons [body mass index (in kg/m2) < or = 27] and matched control subjects who had never been obese. DESIGN: We performed both an individual subject data meta-analysis and a traditional meta-analysis. RESULTS: The individual subject data meta-analysis included 124 formerly obese and 121 control subjects. RMR adjusted for differences in fat-free mass and fat mass was 2.9% lower in formerly obese subjects than in control subjects (P = 0.09). A low relative RMR (> 1 SD below the mean of the control group) was found in 3.3% of the control subjects and in 15.3% of the formerly obese subjects [difference: 12% (95% CI: 4.7%, 19.3%); P < 0.003]. The traditional meta-analysis was based on 12 studies (including 94 formerly obese and 99 control subjects) and included 3 studies not represented in the individual subject data analysis. In this analysis, relative RMR was lower in the formerly obese group than in the control group by 5.1% (95% CI: 1.7%, 8.6%). CONCLUSIONS: Formerly obese subjects had a 3-5% lower mean relative RMR than control subjects; the difference could be explained by a low RMR being more frequent among the formerly obese subjects than among the control subjects. Whether the cause of the low RMR is genetic or acquired, the existence of a low RMR is likely to contribute to the high rate of weight regain in formerly obese persons.     

Effect of a very-low-calorie diet on body composition and resting metabolic rate in obese men and women

Very-low-calorie diets (VLCDs) provide a rapid decrease in total body weight, but limited data are available regarding the extent of fat loss and whether body fat distribution is altered. The purpose of this study was to investigate body composition, body fat distribution, and resting metabolic rate in obese men and women and to compare bioelectrical impedance analysis (BIA) with hydrodensitometry before and after 12 weeks of treatment in a VLCD program. Body composition was assessed by hydrodensitometry and BIA. Circumference measures were used to determine waist:hip and waist:thigh ratios. Seventeen subjects lost a mean of 24.2 kg. A mean of 75.5% of the weight loss was adipose tissue as measured by hydrodensitometry. BIA underestimated body fat percentage compared with hydrodensitometry in this obese population. Waist:hip and waist:thigh ratios showed a small but significant decrease, implying a decreased risk for diabetes and cardiovascular disease after weight loss. Resting metabolic rate, as measured by oxygen consumption, dropped 23.8% during the 12 weeks of the VLCD. The findings indicate that a VLCD can provide a rapid weight loss of more than 75% fat and a concomitant decrease in waist:hip and waist:thigh ratios. The findings also indicate that BIA may not be a useful tool in assessing fat loss in obese subjects. Finally, it appears that the decrease in resting metabolic rate that occurs during treatment with VLCD does not correlate with changes in lean body mass.     

Lower resting metabolic rate in the elderly may not be entirely due to changes in body composition

OBJECTIVE: To investigate whether or not the lower resting metabolic rate (RMR) in the elderly is entirely due to changes in body composition. DESIGN: Cross-sectional data of 132 female (age 69.9+/-5.5 y, body mass index (BMI) 26.5+/-4.0 kg/m(2)) and 84 male (age 68.9+/-5.1 y, BMI 26.1+/-2.8 kg/m(2)) participants of the longitudinal study on nutrition and health status in an aging population of Giessen, Germany, as well as that of 159 young women (age 24.8+/-3.0 y, BMI 21.1+/-2.5 kg/m(2)) and 67 young men (age 26.8+/-3.4 y, BMI 23.3+/-2.4 kg/m(2)) were analysed. RMR was measured by indirect calorimetry after an overnight fast and body composition was estimated by bioelectrical impedance analysis and predictive equations from the literature. Analysis of covariance was used to adjust RMR for body composition, body fat distribution and smoking habits. Additionally, RMR that is to be expected theoretically, was calculated on the basis of the subjects' body composition and the specific metabolic rate of the different organs and was compared to measured RMR. RESULTS: Compared to young subjects adjusted RMR was significantly lower in elderly women (5432+/-82 vs 5809+/-70 kJ/day, P<0.01) and men (6971+/-99 vs 7558+/-121 kJ/day, P<0.001). In both elderly women and men, measured RMR was markedly lower than calculated RMR (-625+/-404, -515+/-570 kJ/day). By contrast, measured and calculated RMR were nearly the same in young men (159+/-612 kJ/day); in young women the difference between measured and calculated RMR was only -300+/-457 kJ/day. In both sexes, these differences are significantly larger in the elderly when compared to young adults. CONCLUSION: These results support the point of view that the decline in RMR with advancing age cannot be totally due to changes in body composition.     

Effects of a very-low-calorie diet and physical-training regimens on body composition and resting metabolic rate in obese females

Sixty-nine obese females received 90 d of a liquid diet providing 2184 kJ/d in clinical trials. Groups were diet only (C), diet plus endurance exercise (EE), diet plus weight training (WT), or diet plus endurance exercise and weight training (EEWT). Changes in body weight, percent fat, fat weight, and fat-free mass were not different between groups. Declines in resting metabolic rate (RMR) were approximately 7% to approximately 12% of baseline values with no differences among groups. A significant increase in work capacity (approximately 16%) was shown for EEWT. Strength index showed declines of approximately 6% for C and EE and gains of approximately 3% and approximately 10% for EEWT and WT, respectively. These clinical trials did not show advantages of any exercise regimen over diet alone for weight loss, body-composition changes, or declines in RMR. Improvements in work capacity were limited and strength improved in groups that participated in strength training.     

Effect of 3 weeks of detraining on the resting metabolic rate and body composition of trained males

OBJECTIVE: To examine the hypothesis that detraining decreases the resting metabolic rate (RMR) of long-term exercisers. DESIGN: Eight pairs of subjects were matched for age, mass and training volume. They were then randomly allocated to either a control group (continue normal training) or detraining group (stop normal training but continue activities of daily living). SETTING: Exercise Physiology Laboratory, The Flinders University of South Australia. SUBJECTS: Sixteen male subjects (age 23.1 +/- 4.7 y (s.d.); mass 73.73 +/- 8.9 kg; VO2max 60.2 +/- 6.3 ml. kg-1.min-1; height 180.3 +/- 5.0 cm; body fat 14.6 +/- 5.4%) were selected from a pool of respondents to our advertisements. INTERVENTIONS: Each pair of subjects was measured before and after a 3-week experimental period. RESULTS: Two (groups) x 3 (2-, 3-and 4-compartment body composition models) ANOVAs were conducted on the difference between the pre- and post-treatment scores for percentage body fat, fat-free mass (FFM) and relative RMR (kJ.kg FFM-1.h-1). No significant between-group differences were identified except for the detraining group's small decrease in FFM (0.7 kg, P = 0.05). The main effects for body composition model were all significant; but the overall differences between the multicompartment models and the 2-compartment one were less than their technical errors of measurement. No significant interaction (P = 0.51) resulted from a 2 x 2 ANOVA on the pre- and post-treatment absolute RMR data for the control (315.2 and 311.9 kJ/h) and detraining groups (325.4 and 325.5 kJ/h). CONCLUSIONS: 3-weeks detraining is not associated with a decrease in RMR (kJ/h, kJ.kg FFM-1.h-1) in trained males; hence, our data do not support a potentiation of the RMR via exercise training. The greater sensitivity of the multicompartment models to detect changes in body composition was of marginal value.     

Comparison between Medgem and Deltatrac resting metabolic rate measurements

OBJECTIVE: The primary aims of this trial were to evaluate the reproducibility of a portable handheld calorimeter (Medgem) in a clinical population, and to compare its measures with a calorimeter in typical use with these patients. DESIGN: Cross-sectional clinical validation study. SETTING: Outpatient Clinical Research Center. SUBJECTS: A total of 24 stable home nutrition support patients. INTERVENTIONS: In random order three measures of resting metabolic rate (RMR) were taken after a 4-h fast, 15 min rest and 2-h abstention from exercise. Two measures were taken with the same Medgem (MG) and one with the traditional calorimeter (Deltatrac). Reproducibility of MG measures and their comparability to a Deltatrac measure were assessed by Bland-Altman analysis, with >+/-250 kcal/day established a priori as a clinically unacceptable error. In addition, disagreement between the two types of measures was defined as greater than 10% difference. RESULTS: The mean difference between two MG measures was -6.8 kcal/day, with limits of agreement between 233 and -247 kcal/day and clinically acceptable. The mean difference between the Deltatrac and mean of two MG measures was -162 kcal/day, with limits of agreement between 577 and -253 kcal/day and clinically unacceptable. In all, 80% of the repeated MG RMR measures agreed within 10%, and the mean MG reading agreed with the Deltatrac in 60% of cases. CONCLUSIONS: RMR obtained using the MG calorimeter has an acceptable degree of reproducibility, and is acceptable to patients. The MG measures, however, are frequently lower than traditional measures and require further validation prior to application to practice in this vulnerable patient group.     

北京市城区858例中老年体检人群体成分和静息代谢率分析

目的 了解北京市城区中老年人超重/肥胖率,分析体成分和静息代谢率随年龄改变的趋势。方法 对2014年11月至2015年12月在北京医院体检的51～99岁的858例（男性760例,女性98例）进行体成分和静息代谢率检测。结果 超重率为51.4%,肥胖率为16.9%,且女性超重/肥胖率明显低于男性（P<0.001）;骨骼肌量、肌肉指数、体脂百分比、内脏脂肪面积和静息代谢率在不同年龄段的分布有差异（均P<0.001）。在体重正常组,≥80岁年龄段的骨骼肌量、肌肉指数、静息代谢率显著减少（P<0.05）,体脂百分比和内脏脂肪面积明显增多（P<0.05）;在超重/肥胖组,70～岁年龄段的骨骼肌量、肌肉指数、静息代谢率开始显著减少（P<0.05）,≥80岁年龄段减少更加显著,而70～岁年龄段体脂百分比和内脏脂肪面积明显增多（P<0.05）。结论 北京市城区中老年人超重/肥胖率较高,且男性高于女性;随年龄增长,骨骼肌量、肌肉指数、静息代谢率逐渐减少,而体脂百分比、内脏脂肪面积增加。超重/肥胖人群更早出现体成分和静息代谢率的改变。     

Indirect calorimetry in obese female subjects: Factors influencing the resting metabolic rate

AIM: To evaluate selected factors influencing resting energy expenditure (REE) in obese female subjects.METHODS: Seventy seven 61 obese Caucasian women [mean age of 52.93 ± 13.45 years, and mean body mass index (BMI) of 41.78 ± 11.54 kg/m²] were enrolled; measurements of resting metabolic rate (RMR) by a ventilated, open-circuit system, indirect calorimeter were performed after an overnight fast. Body composition as well as medications, physical parameters, blood samples, disease pattern, and smoking were considered.RESULTS: RMR was significantly associated with body weight (r = 0.732, P < 0.001), body height (r = 0.401, P = 0.008), BMI (r = 0.504, P < 0.001), waist circumference (r = 0.602, P < 0.001), mid-upper arm circumference (r = 0.417, P = 0.006), mid-upper arm muscle circumference (r = 0.344, P = 0.028), total body water (r = 0.339, P = 0.035), body temperature (r = 0.409, P = 0.007), smoking (P = 0.031), serum T₄ levels (r = 0.331, P = 0.036), obstructive sleep apnoea syndrome (OSAS; P = 0.023), impaired glucose tolerance (IGT; P = 0.017) and impaired glycaemic status, including hyperinsulinism, IGT and diabetes mellitus (P = 0.003).CONCLUSION: Future research should be prompted to optimize the procedure of indirect calorimetry to achieve clinical benefits in obese subjects.     

Bulimia nervosa and resting metabolic rate

This study investigated the relationship between bulimia nervosa and resting metabolic rate. It was hypothesized that severe levels of bulimia, characterized by purging through self-induced vomiting as well as restrictive eating patterns, would be associated with a decrease in the rate of energy utilization and thus a lower resting metabolic rate. Forty-two female subjects participated in the metabolic assessment. Twenty-six were given the diagnosis of bulimia nervosa, and only those subjects purging through self-induced vomiting were included. Sixteen nonbulimic women of comparable age, height, and weight were included as a control group. Resting metabolic rate was measured by continuous monitoring of expired oxygen and carbon dioxide fractions by indirect calorimetry via open-circuit spirometry. Mean values of kilocalories per hour per kilogram were utilized as the dependent variable in the statistical analysis. Bulimic subjects were divided into severe and less severe groups using a median split on the Bulimia Test (BULIT) and compared with normals. Results showed a negative correlation between severity of bulimia, as measured by the BULIT, and resting metabolic rate. It was found that severe bulimics had lower resting metabolic rates than less severe bulimics and normals, who did not differ. These data indicate that severe levels of bulimia are associated with lower resting metabolism, although the correlational nature of the data prohibits a direct causal statement regarding bulimic behavior and its effects on metabolism.     

Physical activity and resting metabolic rate

The direct effects of physical activity interventions on energy expenditure are relatively small when placed in the context of total daily energy demands. Hence, the suggestion has been made that exercise produces energetic benefits in other components of the daily energy budget, thus generating a net effect on energy balance much greater than the direct energy cost of the exercise alone. Resting metabolic rate (RMR) is the largest component of the daily energy budget in most human societies and, therefore, any increases in RMR in response to exercise interventions are potentially of great importance. Animal studies have generally shown that single exercise events and longer-term training produce increases in RMR. This effect is observed in longer-term interventions despite parallel decreases in body mass and fat mass. Flight is an exception, as both single flights and long-term flight training induce reductions in RMR. Studies in animals that measure the effect of voluntary exercise regimens on RMR are less commonly performed and do not show the same response as that to forced exercise. In particular, they indicate that exercise does not induce elevations in RMR. Many studies of human subjects indicate a short-term elevation in RMR in response to single exercise events (generally termed the excess post-exercise O2 consumption; EPOC). This EPOC appears to have two phases, one lasting < 2 h and a smaller much more prolonged effect lasting up to 48 h. Many studies have shown that long-term training increases RMR, but many other studies have failed to find such effects. Data concerning long-term effects of training are potentially confounded by some studies not leaving sufficient time after the last exercise bout for the termination of the long-term EPOC. Long-term effects of training include increases in RMR due to increases in lean muscle mass. Extreme interventions, however, may induce reductions in RMR, in spite of the increased lean tissue mass, similar to the changes observed in animals in response to flight.     

大连市成年人静息心率与代谢综合征的关系

目的 探究大连市成年人静息心率(resting heart rate,RHR)与代谢综合征(metabol-ic syndrome,MS)之间的关系.方法 选取2015年1月1日-2017年12月31日在辽宁省大连市大连医科大学附属医院体检中心体检的人员作为研究对象,采用x2检验对不同心率组间MS患病率进行比较.利用二...     

Weight loss and change in resting metabolic rate

The relation between change in resting metabolic rate (RMR) and change in fat-free mass (FFM) after weight loss is not well understood and is often inappropriately expressed in kilocalories per unit of FFM. We measured RMR and FFM in 35 obese patients enrolled in a conservative weight-loss program. RMR per kilogram FFM was not different after weight loss. However, the regression of delta RMR on delta FFM revealed that the decline in RMR tended to be greater than could be accounted for by loss of FFM. At initial test and retest, body fat (Fat) was not a predictor of RMR after FFM had been taken into account but delta Fat significantly contributed to the prediction of delta RMR when added to the equation after delta FFM. Thus, people losing larger amounts of weight had declines in RMR greater than could be accounted for by loss of FFM. Self-reported age of onset of obesity was not related to delta RMR.