Differences in daily energy expenditure in lean and obese women: the role of posture allocation

Objective: A low resting metabolic rate (RMR) is considered a risk factor for weight gain and obesity; however, due to the greater fat‐free mass (FFM) found in obesity, detecting an impairment in RMR is difficult. The purposes of this study were to determine the RMR in lean and obese women controlling for FFM and investigate activity energy expenditure (AEE) and daily activity patterns in the two groups. Methods and Procedures: Twenty healthy, non‐smoking, pre‐menopausal women (10 lean and 10 obese) participated in this 14‐day observational study on free‐living energy balance. RMR was measured by indirect calorimetry; AEE and total energy expenditure (TEE) were calculated using doubly labeled water (DLW), and activity patterns were investigated using monitors. Body composition including FFM and fat mass (FM) was measured by dual energy X‐ray absorptiometry (DXA). Results: RMR was similar in the obese vs. lean women (1601 ± 109 vs. 1505 ± 109 kcal/day, respectively, P = 0.12, adjusting for FFM and FM). Obese women sat 2.5 h more each day (12.7 ± 3.2 h vs. 10.1 ± 2.0 h, P < 0.05), stood 2 h less (2.7 ± 1.0 h vs. 4.7 ± 2.2 h, P = 0.02) and spent half as much time in activity than lean women (2.6 ± 1.5 h vs. 5.4 ± 1.9 h, P = 0.002). Discussion: RMR was not lower in the obese women; however, they were more sedentary and expended less energy in activity than the lean women. If the obese women adopted the activity patterns of the lean women, including a modification of posture allocation, an additional 300 kcal could be expended every day.     

胰岛素强化治疗对胃癌围手术期营养代谢的影响：随机对照研究

目的:探讨胃癌围手术期能量及营养物质的代谢特点,研究强化胰岛素治疗对围手术营养代谢的影响.方法:选取胃中、下部癌病理诊断明确并且外科病房ICU住院时间不少于24h的患者64例,取得知情同意后随机分到强化胰岛素治疗(IIT)血糖控制在4.4～6.1 mmol/L.和传统治疗(CIT)组血糖控制在10mmol/L以下;应用CCM营养代谢监测系统测定围手术期静息能量消耗(REE),呼吸商(RQ),每公斤体重静息能量消耗(REE/kg)和脂肪氧化比率,应用多频人体生物电阻抗分析仪测定围手术期人体组分的变化及应用稳态模式评估法计算胰岛素抵抗指数(HOMA-IR).结果:64例病人入选,每组32例,手术创伤引起术后第1、3天REE水平增加约22%和12%,呼吸商降低至0.759和0.791,REE/kg增加28 kcal/kg和26 kcal/kg,脂肪氧化比率增加至78%和65%,Ln-HOMA-IR明显增加(P<0.05);IIT治疗能降低术后第1、3天Ln-HOMA-IR和REE/kg水平;术后人体指标如细胞内液、脂肪组织、蛋白组织、肌肉组织、瘦体组织和体质量较术前水平明显降低(P<0.05);IIT能明显减少脂肪组织、蛋白组织和细胞内液的消耗量(P=0.009,t=0.026).结论:IIT能够有效降低胃癌围手术期胰岛素抵抗程度、降低静息能量消耗的水平和减少脂肪及蛋白质的消耗.     

Influence of ascorbic acid on the thermic effect of feeding in overweight and obese adult humans

The thermic effect of feeding (TEF: increase in energy expenditure following acute energy intake) is an important physiological determinant of total daily energy expenditure and thus energy balance. Approximately 40% of TEF is believed to be mediated by sympathoadrenal activation and consequent beta-adrenergic receptor stimulation of metabolism. In sedentary adults, acute administration of ascorbic acid, a potent antioxidant, augments the thermogenic response to beta-adrenergic stimulation. We hypothesized that acute ascorbic acid administration augments TEF in sedentary overweight and obese adults. Energy expenditure was determined (ventilated hood technique) before and 4 h after consumption of a liquid-mixed meal (caloric equivalent 40% of resting energy expenditure (REE)) in 11 sedentary, overweight/obese adults (5 men, 6 women; age: 24 +/- 2 years; BMI: 28.5 +/- 1.0 kg/m(2) (mean +/- s.e.)) on two separate, randomly ordered occasions: during continuous intravenous administration of saline (placebo control) and/or ascorbic acid (0.05 g/kg fat-free mass). Acute ascorbic acid administration prevented the increase in plasma concentration of oxidized low-density lipoprotein in the postprandial state (P = 0.04), but did not influence REE (1,668 +/- 107 kcal/day vs.1,684 +/- 84 kcal/day; P = 0.91) or the area under the TEF response curve (33.4 +/- 2.4 kcal vs. 30.5 +/- 3.6 kcal; P = 0.52) (control vs. ascorbic acid, respectively). Furthermore, acute ascorbic acid administration had no effect on respiratory exchange ratio, heart rate, or arterial blood pressure in the pre- and postabsorptive states (all P > 0.64). These data imply that the attenuated TEF commonly observed with sedentary lifestyle and obesity is not modulated by ascorbic acid-sensitive oxidative stress.     

Evaluation of a multisensor armband in estimating energy expenditure in obese individuals

Objective: To examine the reliability and validity of the SenseWear Pro 2 Armband (SWA; Body Media, Pittsburgh, PA) during rest and exercise compared with indirect calorimetry (IC) in obese individuals. Research Methods and Procedures: Energy expenditure was assessed during rest with the SWA and IC in 142 obese adults (37 men and 105 women, BMI = 42.3 ± 7.0) and in 25 lean and overweight adults (BMI = 25.3 ± 3.2) who were used as a comparison group. Twenty‐nine of the obese adults also participated in three separate short exercise sessions including cycle ergometry, stair stepping, and treadmill walking. Results: The repeatability of SWA estimates in obese subjects was high (r = 0.88, p < 0.001). The SWA generally underestimated the resting energy expenditure (REE) (1811 ± 346 vs. 1880 ± 382 kcal/d) and highly overestimated the energy expenditure during the exercise sessions in obese individuals. REE estimations by SWA were significantly correlated with fat‐free mass (r = 0.88, p < 0.001). Bland‐Altman plots based statistical analysis for the estimated REE, and measured IC showed a low agreement (Total Error > 20% but Systematic Error < 5%) between the two methods in obese subjects, although they showed a high correlation and a very good agreement in lean and overweight patients. Discussion: The SWA is an easy to handle, practical, new portable device for measuring energy expenditure. The accuracy of the SWA appeared to be poor in the obese subjects we examined, especially those with high REE both in rest and exercise. We believe that it is necessary to incorporate new, obesity‐specific algorithms in the relative software.     

Greater Than Predicted Decrease in Resting Energy Expenditure and Weight Loss: Results From a Systematic Review

Changes in resting energy expenditure (EE) during weight loss are said to be greater than what can be expected from changes of body mass, i.e., fat mass (FM) and fat‐free mass (FFM) but controversy persists. The primary focus of this study was to investigate whether there is a greater than predicted decrease in resting EE during weight loss in a large sample size through a systematic review. The study data were weighted and a partial residual plot followed by a multiple regression analysis was performed to determine whether FM and FFM can predict the changes of resting EE after weight loss. Another subgroup of studies from which all necessary information was available was analyzed and compared against the Harris—Benedict (HB) prediction equation to determine whether the changes in resting EE were greater than what was expected. Subjects lost 9.4 ± 5.5 kg (P < 0.01) with a mean resting EE decline of 126.4 ± 78.1 kcal/day (P < 0.01). Changes in FM and FFM explained 76.5% and 79.3% of the variance seen in absolute resting EE at baseline and post‐weight loss, respectively (P < 0.01). Analysis of the 1,450 subject subgroup indicated an ～29.1% greater than predicted decrease in resting EE when compared to the HB prediction equation (P < 0.01). This analysis does not support the notion of a greater than predicted decrease in resting EE after weight loss.     

Accuracy of SenseWear Pro2 Armband to Predict Resting Energy Expenditure in Childhood Obesity

Objective: The accuracy of the SenseWear Pro2 Armband (SWA) in estimating resting energy expenditure (REE) in children and adolescents with obesity, using indirect calorimetry (IC) as a reference was evaluated. Design and Methods: REE was assessed using both the SWA and IC in 40 obese subjects (26 M/14 F, age 11.5 ± 2.57 years, z‐score BMI 3.14 ± 0.53). The agreement between methods was assessed by the Bland‐Altman procedure. The relationship between REE assessments and patients' characteristics was also analyzed. Results : SWA‐ and IC‐derived estimates of REE showed a significant correlation (r = 0.614; P < 0.001), but the SWA overestimated mean REE by 13% (P < 0.001). Age and kilogram of fat‐free mass (kg‐FFM) were significantly correlated with both REE estimation by SWA (r = 0.434 and r = 0.564, respectively) and IC (r = 0.401 and r = 0.518, respectively). Only kg‐FFM was demonstrated to be the main predictor factor of REE variability (r² 79% SWA; 75% IC). Conclusions: The SWA overestimated mean REE in childhood obesity, suggesting that the SWA and IC are not yet interchangeable methods. This would require improving the SWA by developing better algorithms for predicting REE and, probably, bias in each individual REE could be reduced by an adjustment for subjects' kg‐FFM.     

Metabolically active components of fat free mass and resting energy expenditure in nonobese adults

Resting energy expenditure (REE) and components of fat-free mass (FFM) were assessed in 26 healthy nonobese adults (13 males, 13 females). Detailed body composition analyses were performed by the combined use of dual-energy X-ray absorptiometry (DEXA), magnetic resonance imaging (MRI), bioelectrical impedance analysis (BIA), and anthropometrics. We found close correlations between REE and FFM(BIA) (r = 0.92), muscle mass(DEXA) (r = 0.89), and sum of internal organs(MRI) (r = 0.90). In a multiple stepwise regression analysis, FFM(BIA) alone explained 85% of the variance in REE (standard error of the estimate 423 kJ/day). Including the sum of internal organs(MRI) into the model increased the r(2) to 0.89 with a standard error of 381 kJ/day. With respect to individual organs, only skeletal muscle(DEXA) and liver mass(MRI) significantly contributed to REE. Prediction of REE based on 1) individual organ masses and 2) a constant metabolic rate per kilogram organ mass was very close to the measured REE, with a mean prediction error of 96 kJ/day. The very close agreement between measured and predicted REE argues against significant variations in specific REEs of individual organs. In conclusion, the mass of internal organs contributes significantly to the variance in REE.     

Determinants of resting energy expenditure in obese and non-obese children and adolescents

Resting energy expenditure (REE) is the largest component of total daily energy expenditure. Objectives of this study were to examine whether differences in REE exist after obesity develops in a group of children and adolescents, and to determine the effects of body composition, gender, age, pubertal development and parental obesity on REE. In 116 Caucasian children and adolescents (57 obese and 59 non-obese), aged 7.8 to 16.6 years, REE was assessed by open-circuit indirect calorimetry and different anthropometric variables and bioelectrical impedance were obtained (weight, height, skinfold thicknesses, waist and hip circumferences). Anthropometric indices and body compartments were calculated: the body mass index, surface area (SA), fat-free mass (FFM), fat-mass (FM) and percentage of FM. Differences between obese and non-obese subjects were tested and stepwise multiple regression analysis was performed with REE as dependent variable. Results show that REE was significantly higher in obese than in non-obese children and adolescents but REE/FFM ratio was not significantly different between these groups. In the non-obese group, FFM explained 73.1% of the variability in REE and gender, age and SA added 3.8%, 2.6%, and 2.6% to it, respectively. In the obese group, FFM was also the most powerful predictor of REE with 72.3%, followed by waist circumference and age with 2.5% and 2.1%, respectively. These results show that REE differences between obese and lean children do not seem to justify the maintenance of obesity. The main determinant of REE is FFM in both groups. No significant contribution of FM, pubertal development or parental obesity in REE was found in children and adolescents.     

Comparison between predicted and measured resting energy expenditures in Korean male collegiate soccer players

[Purpose] This study aimed to evaluate the differences between predicted resting energy expenditure (REE), using fat-free mass (FFM)-based prediction equations, and measured REE in Korean male collegiate soccer players.[Methods] Fifteen male collegiate soccer players (18-21 years) participated in this study. The REE measurements were conducted using the Douglas bag method. Body composition was measured by dual-energy X-ray absorptiometry (DXA). The differences between the measured REE and predicted REE, using the five FFM-based REE equations, were analyzed using the t-test, calculation of errors, regression analysis, and the Bland-Altman method.[Results] The Cunningham (1980) and ten Haaf and Weijs (2014) equations showed significantly overestimated REE (1,808 ± 99 kcal/d, p <0.01; 1,838 ± 103 kcal/d, p <0.01; respectively), but the Owen (1988), Taguchi (2011), and Kim (2015) equations’ estimations were not significantly different from the measured REE (1,589 ± 106 kcal/d, 1,640 ± 124 kcal/d, and 1,622 ± 68 kcal/d, respectively). The Taguchi equation gave the best prediction of REE with the lowest constant error (-6 ± 125) and effect size (-0.05), and a non-significant proportional bias (p = 0.95).[Conclusion] The Taguchi equation is recommended for predicting REE in Korean collegiate soccer players. The selection process of a REE-prediction equation must take into consideration the target population’s characteristics. Future studies are recommended to evaluate the validity of the different FFM-based REE-prediction equations in various Korean athletes.     

胰岛素强化治疗对胃癌围手术期营养代谢的影响：随机对照研究

目的：探讨胃癌围手术期能量及营养物质的代谢特点,研究强化胰岛素治疗对围手术营养代谢的影响。方法：选取胃中、下部癌病理诊断明确并且外科病房ICU住院时间不少于24h的患者64例,取得知情同意后随机分到强化胰岛素治疗（IIT）组血糖控制在4.4~6.1mmol/L,和传统治疗（CIT）组血糖控制在10mmol/L以下;应用CCM营养代谢监测系统测定围手术期静息能量消耗（REE）,呼吸商（RQ）,每公斤体重静息能量消耗（REE/kg）和脂肪氧化比率,应用多频人体生物电阻抗分析仪测定围手术期人体组分的变化及应用稳态模式评估法计算胰岛素抵抗指数（HOMA-IR）。结果：64例病人入选,每组32例,手术创伤引起术后第1、3天REE水平增加约22%和12%,呼吸商降低至0.759和0.791,REE/kg增加28kcal/kg和26kcal/kg,脂肪氧化比率增加至78%和65%,Ln-HOMA-IR明显增加（P〈0.05）;IIT治疗能降低术后第1、3天Ln-HOMA-IR和REE/kg水平;术后人体指标如细胞内液、脂肪组织、蛋白组织、肌肉组织、瘦体组织和体质量较术前水平明显降低（P〈0.05）;IIT能明显减少脂肪组织、蛋白组织和细胞内液的消耗量（P=0.009,t=0.026）。结论：IIT能够有效降低胃癌围手术期胰岛素抵抗程度、降低静息能量消耗的水平和减少脂肪及蛋白质的消耗。     

Proinflammatory cytokines and the hypermetabolism of children with sickle cell disease

Sickle cell anemia (HbSS) includes chronic inflammation, but the origin is unclear. We hypothesized that in stable HbSS patients the inflammation was associated with hypermetabolism. We compared selected hypermetabolic and key immunomodulator indicators in HbSS versus control children and examined associations between measures of hypermetabolism and inflammation. Twelve fasting asymptomatic HbSS children 6-12 years and 9 controls matched for age, gender and fat mass (FM) were studied. Proportional reticulocyte count (retic%) and resting energy expenditure (REE) represented hypermetabolism, and C-reactive protein (CRP) indicated inflammation. Proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), chemokine monocyte chemoattractant protein-1 (MCP-1), and energy balance cytokine leptin were measured. Methods were indirect calorimetry, enzyme-linked immunosorbent assay, and radioimmunoassay. Statistical analysis included simple correlation and regression analysis. REE (51 +/- 6 vs. 43 +/- 12 kcal/kg per fat-free mass (FFM), mean +/- SD), retic% (12 +/- 4 vs. 0.7 +/- 0.3%), CRP (5 +/- 3 vs. 0.3 +/- 0.4 mg/liter), and IL-6 (71 +/- 40 vs. 20 +/- 7 pg/ml) were significantly higher for HbSS than controls (P < 0.05). Conversely, leptin (0.1 +/- 0.1 vs. 2 +/- 1 microg/liter per kgFM) and MCP-1 (34 +/- 5 vs. 41 +/- 4 pg/ml) were significantly lower for the HbSS subjects (P < 0.01). TNF-alpha was not significantly different. There were no significant associations between REE or retic% and any cytokine measured. However, CRP was significantly associated with REE in HbSS (r = 0.8, P = 0.003) and an important predictor of REE/FFM. We provide new evidence for low circulating levels of inflammatory chemokine MCP-1 in stable HbSS children, confirm mostly low cytokine levels, inflammation, and hypermetabolism and demonstrate association of hypermetabolism with inflammation via CRP but not via cytokines.     

Effect of Diet Composition and Weight Loss on Resting Energy Expenditure in the POUNDS LOST Study

Weight loss reduces energy expenditure, but it is unclear whether dietary macronutrient composition affects this reduction. We hypothesized that energy expenditure might be modulated by macronutrient composition of the diet. The Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST study, a prospective, randomized controlled trial in 811 overweight/obese people who were randomized in a 2 × 2 design to diets containing 20en% or 40en% fat and 15en% or 25en% protein (diets with 65%, 55%, 45%, and 35% carbohydrate) provided the data to test this hypothesis. Resting energy expenditure (REE) was measured at baseline, 6, and 24 months using a ventilated hood. REE declined at 6 months by 99.5 ± 8.0 kcal/day in men and 55.2 ± 10.6 kcal/day in women during the first 6 months. This decline was related to the weight loss, and there was no difference between the diets. REE had returned to baseline by 24 months, but body weight was still 60% below baseline. Measured REE at 6 months was significantly lower than the predicted (?18.2 ± 6.7 kcal/day) and was the result of significant reductions from baseline in the low‐fat diets (65% or 55% carbohydrate), but not in the high fat diet groups. By 24 months the difference had reversed with measured REE being slightly but significantly higher than predicted (21.8 ± 10.1 kcal/day). In conclusion, we found that REE fell significantly after weight loss but was not related to diet composition. Adaptive thermogenesis was evident at 6 months, but not at 24 months.     

Subclinical Hypothyroidism in Obese Patients: Relation to Resting Energy Expenditure,Serum Leptin,Body Composition,and Lipid Profile

Objective: To evaluate whether subclinical hypothyroidism (SH) affects resting energy expenditure (REE) as well as body composition, lipid profile, and serum leptin in obese patients. Research Methods and Procedures: A total of 108 obese patients with SH defined as normal free thyroxine levels and thyroid‐stimulating hormone (TSH) values of >4.38 μU/ml (mean ± 2 SD of the values of our reference group of obese patients with normal thyroid function) were compared with a group of 131 obese patients matched for age, sex, and body mass index (BMI) but with normal TSH levels. We assessed estimated daily caloric intake by 7‐day recall, REE by indirect calorimetry, body composition by bioelectrical impedance analysis, serum leptin by radioimmunoassay, and lipid profile (i.e., total cholesterol, high‐density lipoprotein cholesterol, low‐density lipoprotein cholesterol, and triglycerides). Results: All of the variables measured were not different between the euthyroid obese patients and those with SH. In a multiple regression model with REE expressed for kilograms of fat free mass (REE/kgFFM) as a dependent variable and percentage of fat mass, BMI, waist‐to‐hip ratio, age, TSH, free thyroxine, serum leptin, and caloric intake as independent variables, only percentage of fat mass was significantly correlated with REE/kgFFM in both groups. In the SH group only, BMI, waist‐to‐hip ratio, age, and TSH were related to REE/kgFFM and explained 69.5% of its variability. After dividing the patients with SH using a cutoff TSH value of 5.7 μU/ml, which represents 3 SD above the mean of TSH levels of the group of obese patients with normal thyroid function, only REE/kgFFM was significantly different and lower in the group of more severely hypothyroid patients. Discussion: In patients with obesity, SH affects energy expenditure only when TSH is clearly above the normal range; it does not change body composition and lipid profile. We suggest that, at least in obese patients, evaluation of TSH levels may be useful to rule out a possible impairment of resting energy expenditure due to a reduced peripheral effect of thyroid hormones.     

Cardiac output increases independently of basal metabolic rate in early human pregnancy

Early pregnancy is characterized by the institution of a high-flow low-resistance circulation. In this study, we tested the hypothesis that these hemodynamic changes develop independently of changes in basal metabolic rate. In 12 healthy women, we determined and calculated once during the follicular phase (day 5 +/- 2) and at 6, 8, 10, and 12 wk of pregnancy the following variables: body weight and length, body mass index, fat-free mass (FFM), mean arterial pressure (MAP), heart rate (HR), stroke volume, cardiac output (CO), total peripheral vascular resistance (TPVR), resting energy expenditure (REE), FFM REE (REE(FFM)), and respiratory quotient (RQ). At 6 wk of gestational age, HR and CO had increased, whereas MAP and TPVR had decreased. These changes persisted throughout the study period. Meanwhile, REE, REE(FFM), RQ, FFM, and body weight did not change consistently. The changes with pregnancy in hemodynamics did not correlate with those in basal metabolic rate. In early pregnancy, the institution of a high-flow low-resistance circulation develops without a concomitant rise in basal metabolic rate. These findings support the concept that the hemodynamic changes in early pregnancy develop independently of concomitant changes in basal metabolic rate.     

A Weight Reduction Program Preserves Fat‐Free Mass but Not Metabolic Rate in Obese Adolescents

Objective: To determine the effects of a multidisciplinary weight reduction program on body composition and energy expenditure (EE) in severely obese adolescents. Research Methods and Procedures: Twenty‐six severely obese adolescents, 12 to 16 years old [mean BMI: 33.9 kg/m²; 41.5% fat mass (FM)] followed a 9‐month weight reduction program including moderate energy restriction and progressive endurance and resistance training. Body composition was assessed by DXA, basal metabolic rate by indirect calorimetry, and EE by whole‐body indirect calorimetry with the same activity program over 36‐hour periods before starting and 9 months after the weight reduction period. Results: Adolescents gained (least‐square mean ± SE) 2.9 ± 0.2 cm in height, lost 16.9 ± 1.3 kg body weight (BW), 15.2 ± 0.9 kg FM, and 1.8 ± 0.5 kg fat‐free mass (FFM) (p < 0.001). Basal metabolic rate, sleeping, sedentary, and daily EE were 8% to 14% lower 9 months after starting (p < 0.001) and still 6% to 12% lower after adjustment for FFM (p < 0.05). Energy cost of walking decreased by 22% (p < 0.001). The reduction in heart rate during sleep and sedentary activities (?10 to ?13 beats/min), and walking (?20 to ?25 beats/min) (p < 0.001) resulted from both the decrease in BW and physical training. Discussion: A weight reduction program combining moderate energy restriction and physical training in severely obese adolescents resulted in great BW and FM losses and improvement of cardiovascular fitness but did not prevent the decline in EE even after adjustment for FFM.     

Comparisons of energy intake and energy expenditure in overweight and obese women with and without binge eating disorder

The purpose of this study was to determine whether there are differences in energy intake or energy expenditure that distinguish overweight/obese women with and without binge eating disorder (BED). Seventeen overweight/obese women with BED and 17 overweight/obese controls completed random 24-h dietary recall interviews, and had total daily energy expenditure (TDEE) assessed by the doubly labeled water (DLW) technique with concurrent food log data collection. Participants received two baseline dual-energy X-ray absorptiometry (DXA) scans and had basal metabolic rate (BMR) and thermic effect of food (TEF) measured using indirect calorimetry. Results indicated no between group differences in TDEE, BMR, and TEF. As in our previous work, according to dietary recall data, the BED group had significantly higher caloric intake on days when they had binge eating episodes than on days when they did not (3,255 vs. 2,343 kcal). There was no difference between BED nonbinge day intake and control group intake (2,233 vs. 2,140 kcal). Similar results were found for food log data. Dietary recall data indicated a trend toward higher average daily intake in the BED group (2,587 vs. 2,140 kcal). Furthermore, when comparing TDEE to dietary recall and food log data, both groups displayed significant under-reporting of caloric intake of similar magnitudes ranging from 20 to 33%. Predicted energy requirements estimated via the Harris-Benedict equation (HBE) underestimated measured TDEE by 23-24%. Our data suggest that increased energy intake reported by BED individuals is due to increased food consumption and not metabolic or under-reporting differences.     

Evaluation of specific metabolic rates of major organs and tissues: comparison between nonobese and obese women

Elia (1992) identified the specific resting metabolic rates (K(i)) of major organs and tissues in young adults with normal weight: 200 for liver, 240 for brain, 440 for heart and kidneys, 13 for skeletal muscle, 4.5 for adipose tissue and 12 for residual mass (all units in kcal/kg per day). The aim of the present study was to assess the applicability of Elia's K(i) values for obese adults. A sample of young women (n = 80) was divided into two groups, nonobese (BMI <29.9 kg/m(2)) and obese (BMI 30.0-43.2 kg/m(2)). This study was based on the mechanistic model: REE = σ (K(i) × T(i)), where REE is whole-body resting energy expenditure measured by indirect calorimetry and T(i) is the mass of individual organs and tissues measured by magnetic resonance imaging. For each organ/tissue, the corresponding Elia's K(i) value was analyzed respectively for nonobese and obese groups by using stepwise univariate regression analysis. Elia's K(i) values were within the range of 95% confidence intervals (CIs) in the nonobese group. However, Elia's K(i) values were outside the right boundaries of 95% CIs in the obese group and a corresponding obesity-adjusted coefficient was calculated as 0.98, indicating that Elia's values overestimate K(i) by 2.0% in obese adults. Obesity-adjusted K(i) values were 196 for liver, 235 for brain, 431 for heart and kidneys, 12.7 for skeletal muscle, 4.4 for adipose tissue, and 11.8 for residual mass. In conclusion, although Elia's K(i) values were validated in nonobese women, obesity-adjustments are appropriate for application in obese women.     

Resting energy expenditure-fat-free mass relationship: new insights provided by body composition modeling

The relationship between resting energy expenditure (REE) and metabolically active fat-free mass (FFM) is a cornerstone in the study of physiological aspects of body weight regulation and human energy requirements. Important questions, however, remain unanswered regarding the observed linear REE-FFM association in adult humans. This led us to develop a series of REE-body composition models that provide insights into the widely used simple linear REE-FFM prediction model derived experimentally in adult humans. The new models suggest that the REE-FFM relationship in mammals as a whole is curvilinear, that a segment of this function within a FFM range characteristic of adult humans can be fit with a linear equation almost identical to that observed from a composite review of earlier human studies, and that mammals as a whole exhibit a decrease in the proportion of FFM as high metabolic rate organs with greater FFM. The present study thus provides a new approach for examining REE-FFM relationships, advances in a quantitative manner previously observed albeit incompletely formulated REE-body composition associations, and identifies areas in need of additional research.     

Influence of Sibutramine on Energy Expenditure in African American Women

Objective: African American women have a high prevalence of obesity, which partially may be explained by their lower rates of resting energy expenditure (REE). The aim of this study was to examine the influence of acute sibutramine administration on REE and post‐exercise energy expenditure in African American women. Research Methods and Procedures: A total of 15 premenopausal, African American women (age, 29 ± 5 years; body fat, 38 ± 7%) completed a randomized, double‐blind cross‐over design with a 30‐mg ingestion of sibutramine or a placebo. Each trial was completed a month apart in the follicular phase and included a 30‐minute measurement of REE 2.5 hours after sibutramine or placebo administration. This was followed by 40 minutes of cycling at ～70% of peak aerobic capacity and a subsequent 2‐hour measurement of post‐cycling energy expenditure. Results: There was no difference (p > 0.05) in REE (23.70 ± 2.81 vs. 23.69 ± 2.95 kcal/30 min), exercise oxygen consumption (1.22 ± 0.15 vs. 1.25 ± 0.15 liter/min), and post‐cycling energy expenditure (104.2 ± 12.7 vs. 104.9 ± 11.4 kcal/120 min) between the sibutramine and placebo trials, respectively. Cycling heart rate was significantly higher (p = 0.01) during the sibutramine (158 ± 14 beats/min) vs. placebo (150 ± 12 beats/min) trials. Discussion: These data demonstrate that acute sibutramine ingestion does not increase REE or post‐exercise energy expenditures but does increase exercising heart rate in overweight African American women. Sibutramine may, therefore, impact weight loss through energy intake and not energy expenditure mechanisms.