Clinical Nutrition 29 (2010) 347–351 Contents lists available at ScienceDirect Clinical Nutrition journal homepage: http://www.elsevier.com/locate/clnu Original Article Validity of predictive equations for resting energy expenditure in Belgian normal weight to morbid obese women Peter J.M. Weijs a, b, c, d, *, Greet A.A.M. Vansant e, f, g a Department of Nutrition and Dietetics, Hogeschool van Amsterdam, University of Applied Sciences, Amsterdam, The Netherlands Department of Nutrition and Dietetics, Internal Medicine, VU University Medical Center, Amsterdam, The Netherlands c EMGO Institute for Health and Care Research, Amsterdam, The Netherlands d Department of Intensive Care Medicine, VU University Medical Center, Amsterdam, The Netherlands e Department of Nutrition, Public Health Medicine, Catholic University, Leuven, Belgium f University Hospital Gasthuisberg, Leuven, Belgium g LFoRCe (Leuven Food Science and Nutrition Research Centre), Catholic University, Leuven, Belgium b a r t i c l e i n f o s u m m a r y Article history: Received 14 July 2009 Accepted 30 September 2009 Background & aims: Individual energy requirements of overweight and obese adults can often not be measured by indirect calorimetry, mainly due to the time-consuming procedure and the high costs. To analyze which resting energy expenditure (REE) predictive equation is the best alternative for indirect calorimetry in Belgian normal weight to morbid obese women. Methods: Predictive equations were included when based on weight, height, gender, age, fat free mass and fat mass. REE was measured with indirect calorimetry. Accuracy of equations was evaluated by the percentage of subjects predicted within 10% of REE measured, the root mean squared prediction error (RMSE) and the mean percentage difference (bias) between predicted and measured REE. Results: Twenty-seven predictive equations (of which 9 based on FFM) were included. Validation was based on 536 F (18–71 year). Most accurate and precise for the Belgian women were the Huang, Siervo, Muller (FFM), Harris–Benedict (HB), and the Mifflin equation with 71%, 71%, 70%, 69%, and 68% accurate predictions, respectively; bias 1.7, 0.5, þ1.1, þ2.2, and 1.8%, RMSE 168, 170, 163, 167, and 173 kcal/d. The equations of HB and Mifflin are most widely used in clinical practice and both provide accurate predictions across a wide range of BMI groups. In an already overweight group the underpredicting Mifflin equation might be preferred. Above BMI 45 kg/m2, the Siervo equation performed best, while the FAO/WHO/UNU or Schofield equation should not be used in this extremely obese group. Conclusions: In Belgian women, the original Harris–Benedict or the Mifflin equation is a reliable tool to predict REE across a wide variety of body weight (BMI 18.5–50). Estimations for the BMI range between 30 and 40 kg/m2, however, should be improved. Ó 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved. Keywords: Resting energy expenditure Predictive equation Overweight Obesity Indirect calorimetry Validation 1. Introduction Prevalence of overweight and obesity is high and increasing.1,2 Any weight reduction program will try to establish a reachable goal for weight loss and a reachable goal for dietary intake. This requires knowledge of individual energy requirements, and relies on accurate methods of assessment. Since the golden standard, indirect * Corresponding author. Department of Nutrition and Dietetics, School of Sports and Nutrition, Hogeschool van Amsterdam, University of Applied Sciences, Dr. Meurerlaan 8, 1067 SM Amsterdam, The Netherlands. Tel.: þ31205953534; fax: þ31205953400. E-mail address: p.j.m.weijs@hva.nl (P.J.M. Weijs). calorimetry is hardly feasible in most clinical settings, it remains important to use the most accurate predictive equation for resting energy expenditure (REE) in overweight and obese persons.3 Predictive equations have usually been developed in healthy subjects, based on regression analysis of body weight, height, gender and age as independent variables and measured REE by indirect calorimetry as dependent variable. Based on a comparison of published evidence for Harris and Benedict,4 FAO/WHO/UNU weight or weight and height equations,5 Mifflin6 and Owen7,8 equation, Frankenfield et al.,9 an expert panel has advised to use the Mifflin equation for overweight and obese subjects. However, this expert panel also acknowledges that there are limited data to support the use of Mifflin equation in overweight and obese subjects.9 0261-5614/$ – see front matter Ó 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved. doi:10.1016/j.clnu.2009.09.009 348 P.J.M. Weijs, G.A.A.M. Vansant / Clinical Nutrition 29 (2010) 347–351 The level of overweight might be an important factor for accuracy of the predictive equation, but the level of overweight varies among studies. For most equations overweight and obese subjects were included, but their relative contribution to the final equation often remains unclear. Therefore validation of predictive equations should be performed in specific overweight and obese groups of subjects. Recent evaluations of validity of REE predictive equations have been published for overweight and obese subjects3,10–13 and for extremely obese subjects with BMI over 40 kg/m2.14–18 Only a few studies have validated equations for a clearly defined overweight group (BMI 25–30)3,12 or obese group (BMI 30–40).3,10 The range of published REE predictive equations was recently validated for US and Dutch adults,3 including equations based on body composition (fat free mass and fat mass). As part of evidence based practice, the literature was systematically searched for REE predictive equations, and subsequently included REE equations were validated with indirect calorimetry data of Belgian women with BMI ranging from 18.5 to above 50 kg/m2 in order to find the most accurate and precise REE predictive equation for Belgian women. not been physically active before the measurement and the evening before. Oxygen consumption and carbon dioxide production were measured and energy expenditure was calculated by the Weir formula.20 The measurements took place for at least 30 min and only steady state periods of measurement (20 min) were selected. The first 10 min of the measurement was always discarded. Acceptable coefficient of variation was 10%. Body weight, fat free mass (FFM) and fat mass (FM) were assessed y BIA (Bodystat 1500, Euromedix, Leuven, Belgium) immediately after calorimetry when subjects were lying down for at least 30 min, and were still in the fasting state. None of the subjects was using any diuretics or other medication which may give a shift intra/extracellular water compartments. 2.2. REE predictive equations The inclusion of REE predictive equations has been described elsewhere.3 Only the Siervo equation has been reintroduced, since this was based on obese women.11 Based on 136 Dutch overweight and obese (BMI 25–40) subjects (95F, 41M) the following Weijs predictive equation was generated: REE (kcal/d) ¼ weight(kg) 2. Subjects and methods 14:038 þ heightðcmÞ 4:498 þ sexð0 ¼ female; 1 ¼ maleÞ Subjects were recruited at the department of Nutrition, Public Health Medicine (normal weight) and at the Obesity Clinic (University Hospital Gasthuisberg) Leuven over the past years. Inclusion criteria for the original weight loss studies were being female above the age of 18 and a BMI above 28 kg/m2 without any major metabolic complications. Control subjects were healthy women within the same age category but with a BMI <28. Both weight and height were measured under standardized conditions; body composition was determined using the single-frequency bioelectrical impedance method using a validated equation.19 All participants gave informed consent. All procedures were in accordance with ethical standards of the institution. 2.1. Indirect calorimetry and antropometry The indirect calorimetry measurements were performed with a ventilated hood system (Acertys Healthcare NV, Aartselaar, Belgium) which was calibrated with a standard gas every day before use. Measurements were standardized by internal guidelines. The subjects were in supine position and awake. All subjects were fasted overnight and measured in the morning. Subjects had 137.566 age(y) 0.977 221.631.(R2 ¼ 0.69, SEE ¼ 204). This equation has been added based on the assumption that Belgian and Dutch subjects might be similar. Additionally, the Harris–Benedict equation was tested based on ideal body weight (Hamwi equation), ideal body weight plus 25% of overweight ( ¼ adjusted body weight, ABW25), and ideal body weight plus 50% of overweight ( ¼ adjusted body weight, ABW50). 2.3. Statistics Subject characteristics have been analysed across BMI subgroups by ANOVA with post-hoc Bonferroni test. A prediction between 90 and 110% of REE measured was considered an accurate prediction, a prediction below 90% of REE measured was classified as underprediction and a prediction above 110% of REE measured was classified as overprediction. The percentage of patients that had REE predicted within 10% of REE measured was considered a measure of accuracy on the individual level.3,9 The mean percentage difference between REE predicted and measured (bias) was considered a measure of accuracy on a group level. The root mean squared prediction error (RMSE) was used to indicate how Table 1 Subject characteristics per BMI group. BMI-group Age, y Height, cm Weight, kg BMI, kg/m2 REEb, kcal/d REE, kcal/kg FMg, % FM, kg FFMd, kg REE, kcal/ kg FFM RQ a 18.5–25 N ¼ 67 a 25–30 N ¼ 45 30–35 N ¼ 145 35–40 N ¼ 147 40–45 N ¼ 80 45–50 N ¼ 35 > 50 N ¼ 17 Total N ¼ 536 Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD 39.5 166.2 60.1 21.7 1331 22.2 27.2 16.4 44.3 30.2 10.8a 6.9a 6.5a 1.6a 150a 2.0a 5.8a 4.1a 5.6a 2.6a 43.1 163.7 75.1 28.0 1452 19.3 37.5 28.2 46.9 31.3 14.1a 5.7a 5.8b 1.5b 184b 2.1b 6.4b 5.0b 6.2a 4.6ab 41.2 165.5 89.9 32.8 1614 18.0 43.0 38.7 51.2 31.6 11.3a 6.4a 8.0c 1.4c 184c 1.8c 3.0c 4.7c 4.8b 3.4ab 42.1 163,4 100,1 37,4 1675 16,7 46,9 47,0 53,2 31,6 12.9a 6.8a 8.4d 1.5d 208c 1.7d 3.3d 5.1d 5.7b 3.3ab 41.8 164.1 113.5 42.1 1828 16.1 50.1 56.8 56.5 32.5 11.6a 7.0a 9.8e 1.3e 226d 1.7d 2.6e 5.7e 6.0c 3.2bc 40.3 164,2 127.4 47.1 2049 16.1 52.6 67.1 60.3 34.1 10.9a 7.7a 13.6f 1.5f 278e 1.4d 3.4f 8.3f 8.2d 3.4cd 37.8 162.3 139.8 53.0 2157 15.5 55.6 77.7 61.4 35.4 12.3a 7.4a 15.2g 2.4g 279e 1.5d 2.8f 8,4g 9.2d 3.9cd 41.3 164.5 95.3 35.2 1659 17.8 43.7 43.1 52.2 31.8 12.0 6.8 21.5 7.7 285 2.6 8.4 15.8 7.4 3.5 0.8 0.1 0.8 0.0a 0.8 0.1a 0.8 0.1a 0,8 0.1a 0.8 0.1a 0.8 0.1a 0.8 0.1a ANOVA with post-hoc Bonferroni, means þ SD sharing the same character are not significantly different between these BMI groups (age and RQ, NS; height, p ¼ 0.036; other variables p < 0.001). b REE, resting energy expenditure. g FM, fat mass. d FFM, fat free mass. P.J.M. Weijs, G.A.A.M. Vansant / Clinical Nutrition 29 (2010) 347–351 160 349 3. Results FFM and FM (kg) 140 120 100 FM 80 FFM 60 40 20 0 18.5-25 25-30 30-35 35-40 40-45 45-50 >50 BMI group Fig. 1. Body composition of women per BMI group. well the model predicted in our dataset.21–23 Data were analyzed using SPSS 14.0. In earlier studies the Concordance Correlation Coefficient and Bland–Altman were presented, however, they had no function in the selection process and therefore they are not presented in the present study. Table 1 shows the subject characteristics for the 536 Belgian women. In total, 536 women with a BMI range of 18.5–above 50 kg/m2 were included. As could be expected, REE rises with BMI. After correction for fat free mass, the difference between the groups largely disappears, although BMI group is still a significant factor. No differences in respiratory quotients (RQs) were found between the groups. Fig. 1 shows body composition of the women for 7 different BMI groups. Table 2 shows REE in kcal/d, percentage bias, maximum values found for negative error (underprediction) and positive error (overprediction), the RMSE in kcal/d, the percentage accurate predictions and the percentage underpredictions and percentage overpredictions. Fig. 2 shows the percentage accurate predictions for Belgian women across BMI groups for the 5 best performing equations. Most accurate and precise for the Belgian women were the Huang, Siervo, Muller (FFM), original Harris–Benedict, and the Mifflin equation with 71%, 71%, 70%, 69%, and 68% accurate predictions, respectively; bias 1.8, 0.5, þ1.1, þ2.1, and 1.9%, RMSE 168, 170, 163, 167, and Table 2 Evaluation of REE predictive equations in 536 Belgian women based on bias, RMSE and percentage accurate predictiona. REE predictive equation (# refers to reference in supplementary file) REEa (kcal/d) sdb BIAS (%)c Max. negative error (%)d Max. positive error (%)e RMSEf Accurate predictions (%)g Under predictions (%)h Over predic-tions (%)i REE HB19194 HB1984 (#1) Bernstein (#2) Bernstein FFMj (#2) Owen7,8 Owen FFM7,8 Mifflin6 Mifflin FFM6 Livingston25 Schofield Wk (#3) Schofield WHl (#3) FAOw5 FAOwh5 Henry W (#4) Henry WH (#4) DeLorenzo (#5) Siervo11 Lazzer16 (#6) Lazzer FFM16(#6) Muller12 Muller BMIm,12 Muller FFM12 Muller FFMBMI12 Korth (#7) Korth FFM (#7) Huang15 Huang FFM15 Johnstone FFM (#8) Weijs (see Section 2) Weijs, gender specific (#9) HB1984IBW (see Section 2) HB1984ABW25 (see Section 2) HB1984ABW50 (see Section 2) 1657 1675 1687 1362 1861 1477 1361 1614 1440 1581 1672 1661 1703 1691 1651 1613 1733 1635 1737 1681 1692 1688 1659 1661 1717 1642 1614 1597 1713 1815 1800 1331 1433 1518 288 224 219 169 250 156 147 247 147 197 257 241 255 240 248 214 258 251 240 270 251 257 232 233 251 192 232 235 265 312 288 104 114 137 – 2.2 3.0 16.8 13.4 9.5 16.6 1.8 11.7 3.4 2.0 1.4 3.9 3.2 0.6 1.6 5.4 0.5 5.9 2.1 3.0 2.7 1.1 1.2 4.5 0.5 1.7 2.8 4.1 9.9 9.4 17.6 11.6 6.7 – 25.7 24.6 39.7 15.9 35.7 39.8 28.9 36.6 30.4 29.0 29.0 26.5 26.8 27.9 28.4 22.4 29.3 22.5 27.4 24.0 35.1 24.9 25.7 23.5 30.6 27.8 28.7 23.7 22.7 21.0 53.6 45.4 37.1 – 33.0 34.0 8.4 46.7 21.0 8.5 28.0 14.8 27.1 38.3 33.8 38.1 35.3 32.4 26.7 36.4 33.8 37.1 34.4 34.5 33.1 30.9 30.1 36.3 30.8 27.7 26.0 34.4 46.5 42.9 29.7 26.8 26.8 – 167 169 345 260 257 353 173 291 191 212 199 205 193 183 181 182 170 184 168 169 170 163 163 179 183 168 172 172 239 223 424 332 251 – 69 68 19 36 48 23 68 45 67 59 61 60 61 66 66 63 71 59 68 68 65 70 69 63 63 71 69 65 48 49 23 37 52 – 10 9 81 1 50 77 21 54 25 16 16 12 12 16 21 5 16 7 11 9 11 12 13 8 19 18 22 8 3 4 74 58 41 – 21 23 a b c d e f g h i j k l m REE, resting energy expenditure (as measured). SD, standard deviation. BIAS, mean percentage error between preditive equation and measured value. Max. negative error, the largest underprediction that was found with this predictive equation as percentage of measured value. Max. positive error, the largest overprediction that was found with this predictive equation as percentage of measured value. RMSE, root mean squared prediction error (kcal/d). Accurate predictions, the percentage of subjects predicted by this predictive equation within 10% of measured value. Underpredictions, the percentage of subjects predicted by this predictive equation <10% of measured value. Overpredictions, the percentage of subjects predicted by this predictive equation >10% of measured value. FFM, equation based on fat free mass (as opposed to based on body weight). W, equation based on body weight (as opposed to weight and height). WH, equation based on body weight and height (as opposed to weight only). BMI, BMI specific equations for subgroups BMI equal to 18.5–25, 25–30, >30. 63 2 11 1 8 25 23 28 27 18 13 32 13 34 22 23 24 18 18 29 18 11 9 28 49 48 4 5 7 350 P.J.M. Weijs, G.A.A.M. Vansant / Clinical Nutrition 29 (2010) 347–351 Accurate predictions (%) 90 85 80 Huang 75 Siervo HB1919 70 Mifflin MullerFFM 65 60 55 50 18.525 25-30 30-35 35-40 40-45 45-50 >50 BMI groups Fig. 2. Percentage accurate REE predictions for Belgian women per BMI category for the 5 best scoring equations. 173 kcal/d. The widely used original HB and Mifflin equations might be preferred over new equations, with Mifflin providing more underpredictions and HB more overpredictions. Accurate predictions were consistent across BMI groups except for BMI 30– 40, which had fairly low accuracy. The Weijs equation performed well with 87% accurate predictions in the normal weight group, however, provided no advantage over the original Harris–Benedict or Mifflin equation in the obese groups. Above BMI 45 kg/m2, the Siervo equation performed best, while the FAO/WHO/UNU or Schofield equations should not be used in this extremely obese group (FAOwh 45–50, 51%; FAOwh >50, 29%; SchofieldWH 45–50, 37%; SchofieldWH >50, 29%). Using ideal or adjusted body weight for Harris–Benedict (HB1984) did not improve the REE prediction. 4. Discussion From this study it appears that resting energy expenditure for Belgian normal weight to morbid obese women can safely be predicted with the original Harris–Benedict (HB) or the Mifflin equation. Mifflin might even be preferred in an already overweight and obese group, since it provides more underpredictions and less overpredictions of REE relative to HB. Although the Huang, the Siervo and the Muller (FFM) equations also performed consistent across BMI groups, including the BMI >50 group, the HB and Mifflin equations are already widely used in clinical practice. It is important to notice that all REE predictive equations performed least for the BMI range 30–40. This group is frequently seeking help for weight loss and REE estimations should still be improved for this very large group of people. The Siervo equation performed best at BMI >45. While the FAO/WHO/UNU or Schofield equations should not be used for BMI >45 kg/m2. This is also important since the Schofield equation is most recommended in guidelines in Belgium. Recently the validity of the same set of equations has been assessed by Weijs3 for US and Dutch adults with BMI 25–40, which provided clear evidence for the Mifflin equation to be the preferred equation for the US adults. For the Dutch there was not one single accurate equation. For the Dutch adults with BMI 25–40 kg/m2, new Weijs equations have been developed, a general equation with weight, height, age, and gender as variables and two gender specific equations with weight, height, and age as variables. The gender specific equation was cross-validated in Dutch adults and provided 80% accurate predictions, in line with the Mifflin equation for US adults with BMI 25–40. The general equation including weight, height, age, and gender performed less by cross-validation in the Dutch group BMI 25–40, and performed very well in Belgian women BMI 18.5–25. Whether the HB or Mifflin equation was also the best choice for overweight and obese female Belgian inpatients and outpatients remains to be established. A recent review by an expert panel9 advised the Mifflin equation for overweight and obese subjects. This expert panel acknowledges that there are limited data to support the use of Mifflin equation in overweight and obese subjects. This evidence has now been provided by Weijs,3 however, only for US and Dutch adults. It seems that the Mifflin equation would also perform well in overweight and obese Belgian women. The Dutch women were taller and heavier within each BMI group compared to the US group. The mean height and weight of the Belgian women with BMI 25–30 and BMI 30–35 are almost identical to the mean values of the US group,3 which is in line with a much better performance of the US Mifflin equation in the Belgian overweight and obese women compared to the Dutch group. The evidence for the Mifflin equation to be accurate is now extended to the more obese groups, although not reaching 80% accurate predictions. Recent evaluations of validity of REE predictive equations have been published for overweight and obese subjects10–13 and for extremely obese subjects.14–18 The accuracy rate found with the Mifflin equation in the present study came very close to the accuracy rate found by Frankenfield10 (68 vs. 70%). There is more support for the Mifflin equation in European American females,24 males25 and in extremely obese females.17 Also the original HB has been found acceptable in a broad weight range12 and in extremely obese.14,16 Like in the present study, Frankenfield10 found the original HB equation to perform better in the morbidly obese (BMI >40) than in the next lowest class (BMI 30–40). The study by Lazzer et al.,16 evaluated REE of women with BMI >40 and also found the original HB equation to perform best together with Siervo, then the FAOwh and Huang, and then the Mifflin equation. Accurate predictions were within the 5% limit, and therefore the actual numbers cannot be compared. However, there seems to be no consensus for the use of one preferred REE equation. This might be explained by differences in, e.g. subject group composition, methodology and statistics.3 Measurement conditions in this study were very strictly standardized which is certainly a strong point of this study. Only women were studied for the simple reason that mainly women attend the Obesity Clinic. To create a comparable group, the normal weight persons were also only women. In the Belgian population, the prevalence of obesity is still rising, comparable with most Western countries. At this moment, about 30% of the adult women are overweight while 10% is obese (BMI > 30 kg/m2). For this study, severely obese women could be included since a University Hospital (third line) was involved. Most women did multiple attempts to lose weight before, but did not succeed. It is advisable to validate REE prediction equations for every single specific population, since prediction equations are expected to be valid for the original population only.26 This is especially true for individual accuracy: the percentage of accurate predictions. There is still, room for improvement of REE predictive equations in overweight and obese women, especially the very large BMI 30–40 group. In conclusion, this study again demonstrates that there is a wide variation in accuracy for REE predictive equations. For Belgian women, ranging from normal weight to morbidly obese, either the original Harris–Benedict or the Mifflin equations can be used. Further improvement of accuracy from 71% to >80% should be strived for, since this has been possible for the Mifflin equation in the US and the Weijs equation in the Dutch group. Whether the HB or Mifflin equation was also the best choice for overweight and obese female Belgian inpatients and outpatients remains to be established. Conflict of interest All authors have no conflict of interest to declare. P.J.M. Weijs, G.A.A.M. Vansant / Clinical Nutrition 29 (2010) 347–351 Acknowledgements Thanks to Ageeth Hofsteenge for her contribution in literature search. PW and GV designed the study, performed literature search, data analysis, and wrote the manuscript. References 1. Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM. Prevalence of overweight and obesity in the United States, 1999–2004. JAMA 2006;295:1549–55. 2. Schokker DF, Visscher TL, Nooyens AC, van Baak MA, Seidell JC. Prevalence of overweight and obesity in the Netherlands. Obes Rev 2007;8:101–8. 3. Weijs PJ. Validity of predictive equations for resting energy expenditure in US and Dutch overweight and obese class I and II adults aged 18–65 y. Am J Clin Nutr 2008;88(4):959–70. 4. Harris JA, Benedict FG. A biometric study of basal metabolism in man. Washington, DC: Carnegie Institute of Washington; 1919. 5. FAO/WHO/UNU. Energy and protein requirements. Geneva: WHO; 1985. WHO Technical Report Series. 6. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51:241–7. 7. Owen OE, Kavle E, Owen RS, Polansky M, Caprio S, Mozzoli MA, et al. A reappraisal of caloric requirements in healthy women. Am J Clin Nutr 1986;44:1–19. 8. Owen OE, Holup JL, D’Alessio DA, Craig ES, Polansky M, Smalley KJ, et al. A reappraisal of the caloric requirements of men. Am J Clin Nutr 1987;46:875–85. 9. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc 2005;105:775–89. 10. Frankenfield DC, Rowe WA, Smith JS, Cooney RN. Validation of several established equations for resting metabolic rate in obese and nonobese people. J Am Diet Assoc 2003;103:1152–9. 11. Siervo M, Boschi V, Falconi C. Which REE prediction equation should we use in normal-weight, overweight and obese women? Clin Nutr 2003;22(2):193–204. 12. Müller MJ, Bosy-Westphal A, Klaus S, Kreymann G, Lührmann PM, NeuhäuserBerthold M, et al. World Health Organization equations have shortcomings for 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 351 predicting resting energy expenditure in persons from a modern, affluent population: generation of a new reference standard from a retrospective analysis of a German database of resting energy expenditure. Am J Clin Nutr 2004;80:1379–90. De Luis DA, Aller R, Izaola O, Romero E. Prediction equation of resting energy expenditure in an adult Spanish population of obese adult population. Ann Nutr Metab 2006;50:193–6. Das SK, Saltzman E, McCrory MA, Hsu LKG, Shikora SA, Dolnikowski G, et al. Energy expenditure is very high in extremely obese women. J Nutr 2004;134:1412–6. Huang KC, Kormas N, Steinbeck K, Loughnan G, Caterson ID. Resting metabolic rate in severely obese diabetic and nondiabetic subjects. Obes Res 2004;12:840–5. Lazzer S, Agosti F, Silvestri P, Derumeaux-Burel H, Sartorio A. Prediction of resting energy expenditure in severely obese Italian women. J Endocrinol Invest 2007;30(1):20–7. Dobratz JR, Sibley SD, Beckman TR, Valentine BJ, Kellogg TA, Ikramuddin S, et al. Predicting energy expenditure in extremely obese women. J Parenter Enteral Nutr 2007;31(3):217–27. Boullata J, Williams J, Cottrell F, Hudson L, Compher C. Accurate determination of energy needs in hospitalized patients. J Am Diet Assoc 2007;107(3):393–401. Vansant G. Valiation of the bio-electrical impedance method in severely obese women. Int J Obes 2000;24(Suppl. 1). Abstract 610. Weir JB. New methods for calculating metabolic rate with special reference to protein metabolism. J Physiol 1949;109:1–9. Weijs PJM, Kruizenga HM, van Dijk AE, van der Meij B, Langius JAE, Knol DL, et al. Validation of predictive equations for resting energy expenditure in adult outpatients and inpatients. Clin Nutr 2008;27(1):150–7. Kutner MH, Nachtsheim CJ, Neter J, Li W. Applied linear statistical models. 5th ed. New York: McGraw-Hill/Irwin; 2005. Sheiner LB, Beal SL. Some suggestions for measuring predictive performance. J Pharmacokinet Biopharm 1981;9:503–12. Vander Weg MW, Watson JM, Klesges RC, Eck Clemens LH, Slawson DL, McClanahan BS. Development and cross-validation of a prediction equation for estimating resting energy expenditure in healthy African–American and European–American women. Eur J Clin Nutr 2004;58:474–80. Livingston EH, Kohlstadt I. Simplified resting metabolic rate – predicting formulas for normal-sized and obese individuals. Obes Res 2005;13: 1255–62. Moreira da Rocha EE, Alves VGF, Silva MHN, Chiesa CA, da Fonseca RBV. Can measured resting energy expenditure be estimated by formulae in daily clinical nutrition practice? Curr Opin Clin Nutr Metab Care 2005;8:319–28.