Measured and predicted resting metabolic rate in Italian males and females, aged 18 ± 59 y A De Lorenzo 1,2 *, A Tagliabue 3 , A Andreoli 1 , G Testolin 2 , M Comelli 3 and P Deurenberg 1,4 1 Department of Human Physiology and Nutrition, University `Tor Vergata', Rome, Italy; 2 International Center for the Assessment of Body Composition, University of Milan, Milan, Italy; 3 Department of Applied Health Science, University of Pavia, Pavia, Italy; and 4 Department of Human Nutrition and Epidemiology, Wageningen University, Wageningen, The Netherlands, and Nutrition Consultant in Singapore Objectives: To determine the resting metabolic rate in a sample of the Italian population, and to evaluate the validity of predictive equations for resting metabolic rate (RMR) from the literature in normal and obese subjects. Design: Cross-sectional observational study. Settings: Department of Human Physiology and Nutrition, University `Tor Vergata', Rome. Subjects: A total of 320 healthy subjects, 127 males and 193 females, aged 18 ± 59 y. Methods: Weight, height and resting metabolic rate by indirect calorimetry were measured. Resting metabolic rate was also predicted using equations from the literature. Results: Resting metabolic rate (mean  s.d.) in normal weight subjects was 7983  1007 kJ=24 h (males) and 6127  907 kJ=24 h (females). Measured RMR and predicted RMR values using various equations from the literature were signi®cantly different in males and females, except for the Harris ± Benedict equation and the Scho®eld equations. Also, in overweight and obese subjects the prediction error was generally larger compared to normal-weight subjects for all formulas except for the Harris ± Benedict and Scho®eld formulas. In overweight and obese males but not in females, RMR was lower than in normal-weight subjects after correcting for weight and age differences. Stepwise multiple regression of resting metabolic rate against weight, height and age in males and females did not reveal a prediction formula with a lower prediction error than the Harris ± Benedict or Scho®eld formulas and thus was not further explored. Conclusions: The Harris ± Benedict formula and the Scho®eld formula provide a valid estimation of resting metabolic rate at a group level in both normal-weight and overweight Italians. However, the individual error can be so high that for individual use a measured value has to be preferred over an estimated value. Descriptors: resting metabolic rate; prediction equations; validity; normal weight; overweight; obesity; Italians European Journal of Clinical Nutrition (2001) 55, 208±214 Introduction Resting metabolic rate (RMR) is an important parameter in the assessment of nutritional status in patients and is used for example to calculate the energy needs of a patient who needs parenteral or enteral nutrition (Brandi et al, 1988; MacFie, 1984). In addition information on resting energy expenditure is necessary to calculate energy needs at a population level. For this, the FAO=WHO=UNU (1985) has published prediction formulas for the assessment of resting metabolic rate. The RMR is de®ned as the energy expenditure 10 ± 12 h after a meal, the subject lying supine and completely at physical and mental rest in a thermoneutral environment. It can be measured by direct (heat exchange) or indirect calorimetric (gas exchange) techniques (Garrow & James, 1993), where the latter technique is easier. The accuracy of RMR measurement procedures is fairly good, as the within- subjects coef®cient of variation is about 5% (Weststrate et al, 1989). This is a crucial point, since any bias in RMR assessment would amplify the calculation errors of esti- mated total energy requirements of individuals. Variability ranges of RMR assessment have to be carefully evaluated if total energy expenditure (TEE) is calculated as a multiple of RMR. RMR is the component of energy expenditure that explains the largest proportion of TEE in individuals, but the contribution of a low RMR to the aetiology of obesity is controversial. Given the high prevalence of obesity in many countries (WHO, 1998) and the strong relationship of obesity with several diseases, information on energy meta- *Correspondence: A De Lorenzo, Human Nutrition Unit, University Tor Vergata, Via di Tor Vergata, 135. 00173 Rome, Italy. E-mail: delorenzo@uniroma2.it Guarantor: A De Lorenzo. Contributors: ADL and GT: general project management; AT and AA: daily project management and measurements; MC: data analyses; PD: data analyses and intrepretations. Received 2 May 2000; accepted 6 November 2000 European Journal of Clinical Nutrition (2001) 55, 208±214 ß 2001 Nature Publishing Group All rights reserved 0954±3007/01 $15.00 www.nature.com/ejcn