Whole-body protein turnover and resting energy expenditure in obese, prepubertal children

BACKGROUND: Obesity is becoming more frequent in children; understanding the extent to which this condition affects not only carbohydrate and lipid metabolism but also protein metabolism is of paramount importance. OBJECTIVE: We evaluated the kinetics of protein metabolism in obese, prepubertal children in the static phase of obesity. DESIGN: In this cross-sectional study, 9 obese children (x +/- SE: 44+/-4 kg, 30.9+/-1.5% body fat) were compared with 8 lean (28+/-2 kg ,16.8+/-1.2% body fat), age-matched (8.5+/-0.2 y) control children. Whole-body nitrogen flux, protein synthesis, and protein breakdown were calculated postprandially over 9 h from 15N abundance in urinary ammonia by using a single oral dose of [15N]glycine; resting energy expenditure (REE) was assessed by indirect calorimetry (canopy) and body composition by multiple skinfold-thickness measurements. RESULTS: Absolute rates of protein synthesis and breakdown were significantly greater in obese children than in control children (x +/- SE: 208+/-24 compared with 137+/-14 g/d, P < 0.05, and 149+/-20 compared with 89+/-13 g/d, P < 0.05, respectively). When these variables were adjusted for fat-free mass by analysis of covariance, however, the differences between groups disappeared. There was a significant relation between protein synthesis and fat-free mass (r = 0.83, P < 0.001) as well as between protein synthesis and REE (r = 0.79, P < 0.005). CONCLUSIONS: Obesity in prepubertal children is associated with an absolute increase in whole-body protein turnover that is consistent with an absolute increase in fat-free mass, both of which contribute to explaining the greater absolute REE in obese children than in control children.     

Prediction equations for resting energy expenditure in overweight and normal-weight black and white children

BACKGROUND: Accurate estimation of children's resting energy expenditure (REE) is important for planning dietary therapy. OBJECTIVE: Our objective was to compare the utility of 5 REE prediction equations in a diverse sample of young children. DESIGN: REE was obtained in 502 black and white girls and boys aged 6-11 y by using indirect calorimetry at 4 US sites. Measured REE and REE predicted from the equations were compared. RESULTS: None of the equations provided both accurate and unbiased estimates of REE. Two new sets of sex-specific equations including race as a factor were generated and evaluated. One set used easily measured variables-females: REE = 0.046 x weight - 4.492 x 1/height(2) - 0.151 x race + 5.841; males: REE = 0.037 x weight - 4.67 x 1/height(2) - 0.159 x race + 6.792-and accounted for 72% and 69%, respectively, of REE variance. The other set used body-composition variables-females: REE = 0.101 x fat-free mass + 0.025 x fat mass + 0.293 x height(3) - 0.185 x race + 1.643; males: REE = 0.078 x fat-free mass + 0.026 x fat mass - 2.646 x 1/height(2) - 0.244 x race + 4.8-and accounted for 75% and 71%, respectively, of REE variance. When split by race and adiposity, the small bias generated could be corrected to within 0.25 MJ (60 kcal) of the mean measured value. CONCLUSION: Sex-specific equations must take race into account to predict REE adequately in children.     

肥胖儿童静息能量消耗的初步研究

目的　应用能量代谢仪测定肥胖儿童的静息能量消耗情况,以探讨安静状态下代谢水平与儿童肥胖的关系,同时比较各预测公式的准确性。方法　选取2014年7月至2015年9月在本院儿童保健科就诊的年龄在7～14周岁的儿童。应用间接测热法测静息能量消耗,应用生物电阻抗法测体脂、去脂体质量等体成分。以预测公式值与实测值误差在±10%之内为可以接受的“准确”,超过10%为“高估”,低于10%为“低估”。结果　共纳入研究对象72例,其中超重/肥胖组42例,平均年龄(10.4±1.7)岁,体质量指数(24.76±3.16)kg/m2;对照组共30例,平均年龄(10.4±2.0)岁,体质量指数(15.07±2.11)kg/m2。静息能量消耗以kJ/(kg·d)表示,校正性别、年龄的影响因素后肥胖组儿童每天静息能量消耗［(116.45±20.46)kJ/(kg·d)］明显低于对照组［(138.49±38.77) kJ/(kg·d)］(P=0.000)。各预测公式准确性尚无一致性定论,研究对象实测值与Harris-Benedict、Schofield、WHO、Mifflin、Cunningham、Liu、Jia公式完全符合的准确率分别为50%、47.6%、42.9%、47.6%、33.3%、42.9%、40.5%。结论　肥胖儿童静息能量消耗低于正常儿童,与间接测热法比较,各预测公式准确性均较差。     

先天性心脏病患儿术后静息能量消耗

目的　应用间接测热法（IC）测定先天性心脏病术后机械通气患儿的静息能量消耗（REE）,探究先天性心脏病患儿术后静息能量代谢规律及可能影响因素。方法　纳入2015年2至6月入住上海儿童医学中心心胸外科重症监护室的先天性心脏病术后患儿共150例,于术后4 h应用代谢车测定REE。收集患儿一般人口学和人体测量学资料、临床资料,分析临床因素与REE的相关性。比较患儿术后营养摄入与REE的关系。结果　入组患儿150例,男104例、女46例,中位年龄14（8.3~36.0）个月。IC测得非蛋白呼吸商为0.79±0.20,REE实测值（MREE)（264.76±61.74）kJ/(kg·d),与Schofield公式估算值（278.51±93.42）kJ/(kg·d)比较,差异无统计学意义（P=0.096）,但相关性较低（R2=0.119）;多因素逐步回归分析显示先天性心脏病风险校正评分（RACHS-1）与MREE呈显著正相关（P=0.012）、年龄与MREE呈显著负相关（P=0.010）。术后97.33%（146/150）患儿第1天摄入热量低于MREE。结论　先天性心脏病术后并未出现明显高代谢状态,但影响底物代谢。RACHS-1评分、年龄是影响患儿术后REE的因素。先天性心脏病患儿术后第1天摄入热量普遍低于REE。     

机械通气危重患儿的连续性静息能量消耗测定

目的　探讨机械通气危重患儿的静息能量消耗变化,比较公式估算与间接测热法（IC）所测得的能量消耗之间的差异,分析影响危重患儿代谢状态的可能因素。方法　前瞻性收集2012年9月至2013年9月入住上海儿童医学中心重症监护室、行呼吸机辅助通气、满足IC要求的内科危重症患儿共56例,于机械通气第1、4、7、10天应用代谢车测定其静息能量消耗,并记录患儿的一般临床资料。结果　对56例患儿行IC测定130次,所测得的静息能量消耗值（MREE）在机械通气第1、4、7、10天间比较差异无统计学意义（P=0.379）。MREE与Schofield及WHO公式估算值（PEE）比较差异虽无统计学意义（P值分别为0.917和0.995）,但一致性较差（R2值分别为0.185和0.322）。患儿在机械通气第1天的代谢状态仅与年龄（P=0.000）和身高（P=0.027）相关,与疾病严重程度和临床结局均无关联。结论　机械通气危重患儿的静息能量消耗IC法实测值随机械通气时间变化并不显著,预测公式估算的静息能量消耗值与IC法实际测量值之间一致性较差。建议将IC应用于重症监护病房,指导危重患儿个体化营养支持治疗,以改善患儿临床结局。     

Development and cross-validation of prediction equations for estimating resting energy expenditure in severely obese Caucasian children and adolescents

The objectives of the present study were to develop and cross-validate new equations for predicting resting energy expenditure (REE) in severely obese children and adolescents, and to determine the accuracy of new equations using the Bland-Altman method. The subjects of the study were 574 obese Caucasian children and adolescents (mean BMI z-score 3.3). REE was determined by indirect calorimetry and body composition by bioelectrical impedance analysis. Equations were derived by stepwise multiple regression analysis using a calibration cohort of 287 subjects and the equations were cross-validated in the remaining 287 subjects. Two new specific equations based on anthropometric parameters were generated as follows: (1) REE=(Sex x 892.68)-(Age x 115.93)+(Weight x 54.96)+(Stature x 1816.23)+1484.50 (R(2) 0.66; se 1028.97 kJ); (2) REE=(Sex x 909.12)-(Age x 107.48)+(fat-free mass x 68.39)+(fat mass x 55.19)+3631.23 (R(2) 0.66; se 1034.28 kJ). In the cross-validation group, mean predicted REE values were not significantly different from the mean measured REE for all children and adolescents, as well as for boys and for girls (difference <2 %) and the limits of agreement (+/-2 sd) were +2.06 and -1.77 MJ/d (NS). The new prediction equations allow an accurate estimation of REE in groups of severely obese children and adolescents. These equations might be useful for health care professionals and researchers when estimating REE in severely obese children and adolescents.     

Positive association between resting energy expenditure and weight gain in a lean adult population

BACKGROUND: Weight gain in adulthood is common, from modest gains in developing countries to substantial increases in Western societies. Evidence of the importance of energy expenditure in adult weight change has been limited to studies conducted in Pima Indians, in whom resting energy expenditure (REE) was found to be inversely associated with weight gain. OBJECTIVE: The aim was to determine whether REE was predictive of weight change in lean Nigerian adults. DESIGN: Weight was measured in 744 adults on 2-4 occasions over 5.5 y. REE was measured in the second follow-up examination. Sex-specific, mixed-effects models with REE, fat-free mass, and age as fixed effects were used to test the association between REE and weight change. RESULTS: Adults aged >19 y (n = 352 men and 392 women) were included in these analyses. At baseline, the mean (+/-SD) age was 45.9 +/- 16.1 y for the whole population; the mean weight was 61.4 +/- 10.7 and 58.1 +/- 12.1 kg and body mass index (in kg/m(2)) was 21.4 +/- 3.2 and 23.1 +/- 4.0 for men and women, respectively. Over a mean 5.5 y of follow-up, the age-adjusted weight gain was 0.42 kg/y for the men and 0.59 kg/y for the women. In mixed-effects models, REE was positively associated with weight gain in both men and women (P < 0.001). No significant association was observed in participants who lost weight. CONCLUSIONS: In contrast with observations in overweight Pima Indians, REE adjusted for body size and composition was positively associated with weight gain in lean Nigerian adults. This suggests either that the potential for differential regulation of body weight in lean compared with overweight populations exists or that the increased REE in this population was the result, rather than cause, of weight gain.     

Variability in results from predicted resting energy needs as compared to measured resting energy expenditure in Korean children

Energy needs are influenced by many factors, including ethnicity. Multiple studies have shown that the accuracy of an energy prediction equation varies with the ethnic background of the study population. Therefore, it is crucial to identify the most accurate energy prediction equation to use for a given population. This study compared measured resting energy expenditure to results from commonly-used energy prediction equations to identify the most accurate equation to use for Korean children. Based on previous literature showing wide variation in accuracy of energy prediction equations in different ethnic groups, we hypothesized that results from measured- vs. predicted energy needs would be significantly different in this population. Subjects were 92 South Korean children (38 boys, 54 girls) age 7.7 ± 2.7 years (mean ± SD). Measurements included: resting metabolic rate (TrueOne 2400 metabolic cart), weight/height (digital scale/stadiometer); body fat (BIA, Inbody720), blood pressure (sphingomanometer), triceps skinfold thickness (MD-500 skinfold calipers), muscle mass (Heymsfield's formula) and body surface area (Dubois formula) calculations. Resting energy needs were predicted using the Harris-Benedict, WHO/NAO/FAO, Altman and Dittmer, Maffeis, and Schofield-HW equations, and the Dietary Reference Intake recommendations. Measured and predicted energy needs were significantly correlated (P < .001 for all; range R² = 0.54-0.56), yet significantly different for all equations studied (P < .05) except the Maffeis and Schofield-HW equations. Differences (means ± SD) between measured vs. predicted energy needs ranged from 9.5 ± 123.2 (Schofield-HW) to 199.6 ± 132.7 (WHO/NAO/FAO) kcal/day, where a value closer to zero indicates increased accuracy of the prediction equation to correspond to measured energy needs. Although results from equations studied were significantly correlated with measured resting energy needs, notable discrepancies existed which, over time, could produce undesirable weight changes in Korean children.     

Measurement of resting energy expenditure in a clinical setting

In this study indirect calorimetry for the measurement of a patient's resting energy expenditure (REE) was assessed in clinical practice. REE measured early in the morning after an overnight fast was highly reproducible. REE measured in the afternoon, when patients had consumed their meals, was 15% higher than REE measured in the morning. REE measured at mid-morning was not different from that measured early in the morning, except for patients who had breakfast between the two measurements. Therefore, to avoid the effect of diet-induced thermogenesis in the measurement a patient must be measured in the morning in the post-absorptive state. Variations because of limited physical activities may be neglected, including a short travel from home to the hospital, which implies that REE may be measured on an out-patient basis. The effect of total parenteral nutrition (TPN) on energy expenditure (EE) was a 12% increase. The respiratory quotient (RQ) rose to almost 1.0. Nine days of enteral nutritional support showed only a 3% increase in REE, while RQ increased from 0.78 to 0.87, indicating restored glycogen stores.     

Estimating energy requirements in burned children: a new approach derived from measurements of resting energy expenditure

We examined the determinants of resting energy expenditure (REE) in 127 observations in 56 burned children. Predicted basal energy expenditure (PBEE), body surface area (BSA), and body weight correlated significantly with REE (r2 = 0.76). Days postburn and burn size (% BSA burned) only accounted for 21%, and 24% of the variation in the elevation in REE above PBEE. The single most powerful predictor of REE was PBEE (REE = 1.29 x PBEE); addition of other variables did not improve the prediction. When our recently described activity factor of 1.2 for burn patients is used, the data predict that the average energy requirement to maintain energy balance is 1.55 x PBEE, which is significantly lower than commonly used recommendations, especially for larger burns. The energy required to ensure that 95% of patients achieve energy balance was (1.55 x PBEE) + (2.39 xoff+PBEE0.75), approximately equal to 2 x PBEE. Because the equations presented are derived from measurements of energy expenditure, they represent the most valid approach to estimating energy requirements.     

Prediction of daily energy expenditure during a feeding trial using measurements of resting energy expenditure, fat-free mass, or Harris-Benedict equations

BACKGROUND: During feeding trials, it is useful to predict daily energy expenditure (DEE) to estimate energy requirements and to assess subject compliance. OBJECTIVE: We examined predictors of DEE during a feeding trial conducted in a clinical research center. DESIGN: During a 28-d period, all food consumed by 26 healthy, nonobese, young adults was provided by the investigators. Energy intake was adjusted to maintain constant body weight. Before and after this period, fat-free mass (FFM) and fat mass were assessed by using dual-energy X-ray absorptiometry, and DEE was estimated from the change (after - before) in body energy (DeltaBE) and in observed energy intake (EI): DEE = EI - DeltaBE. We examined the relation of DEE to pretrial resting energy expenditure (REE), FFM, REE derived from the average of REE and calculated from FFM [REE = (21.2 x FFM) + 415], and an estimate of DEE based on the Harris-Benedict equation (HB estimate) (DEE = 1.6 REE). RESULTS: DEE correlated (P < 0.001) with FFM (r = 0.78), REE (r = 0.73), average REE (r = 0.82), and the HB estimate (r = 0.81). In a multiple regression model containing all these variables, R(2) was 0.70. The mean (+/-SEM) ratios of DEE to REE, to average REE, and to the HB estimate were 1.86 +/- 0.06, 1.79 +/- 0.04, and 1.02 +/- 0.02, respectively. CONCLUSIONS: Although a slightly improved prediction of DEE is possible with multiple measurements, each of these measurements suggests that DEE equals 1.60-1.86 x REE. The findings are similar to those of previous studies that describe the relation of REE to DEE measured directly.     

Changes in resting energy expenditure among children undergoing allogeneic stem cell transplantation

BACKGROUND: Because of the effects of chemotherapy and radiotherapy, patients undergoing stem cell transplantation (SCT) are commonly provided nutritional support with parenteral nutrition. The energy and nutrient needs of these patients have not been well studied. OBJECTIVE: The objective was to measure resting energy expenditure (REE), dietary intake, and biochemical and anthropometric changes in children before and after allogeneic SCT. DESIGN: This was a prospective cohort study of 37 children aged 9.1 +/- 6.4 y ( +/- SD) undergoing SCT who were enrolled in an open-label trial of a unique supportive care intervention that included the routine use of oral leucovorin, vitamin E, and ursodeoxycholic acid. Parenteral nutrition was provided to match 100% of measured or estimated REE. REE was measured weekly via indirect calorimetry. RESULTS: Baseline REE was 95% of the predicted age- and sex-matched norms and was significantly correlated with midarm muscle area (r = 0.82, P < 0.001). REE fell to a nadir of approximately 80% of the predicted levels by week 3 after SCT, with a gradual increase in weeks 4 and 5. Arm anthropometric measurements showed no change in triceps skinfold thickness but significant declines in midarm muscle area after SCT. Serum vitamin E remained in the normal range. CONCLUSIONS: Children undergoing SCT show significant declines in REE after transplantation. These changes may be due to alterations in lean body mass. Standard nutritional regimens may lead to overfeeding.