Resting Energy Expenditure Measured by Indirect Calorimetry in Obese Patients: Variation Within Different BMI Ranges

Abstract

Background: The adequate provision of energy for obese patients by estimation without indirect calorimetry (IC) is challenging. The goal was to establish values of kilocalories per kilogram (kcal/kg) for patients in different ranges of body mass index (BMI [kg/m 2 ]) comparable to resting energy expenditure (REE [kcal/kg/d]) measurements by IC. Methods: In 63 overweight (OW) hospitalized patients with BMIs (25.0-29.9) or obesity (OB; ࣙ30), the REE was measured in fasting and fed states. IC was performed with Deltatrac II on patients with enteral or parenteral nutrition, classified by their BMI, in 3 groups: OW (25-29.9), OB (30-39.9), and morbidly obese (ࣙ40). The actual body weight was measured with a microprocessed bed scale or a precision anthropometric scale, and REE was transformed to kcal/kg. Results: Ninety-seven IC measurements were obtained from 63 patients: in 54 on a ventilator, and of 9 with a canopy; 58 in the fasting state; and 39 after reaching measured caloric requirements. The patients' BMIs ranged from 27.3 to 53.4, average of 33.9 ± 6.2. There were no differences in measured REE (mREE) between the fasting and fed states (P > 0.05) within each BMI group; however, differences were observed when comparing the mREE between the groups in the fed state. Conclusion: These results, in kcal/kg/d, suggest using 22.0 for OW, 18.4 for OB, and 16.9 for individuals with BMIs >40. However, we recommend the use of IC to determine REE for the latter subset of patients, since 16.9 kcal/kg/d might be an underestimation. (JPEN J Parenter Enteral Nutr. 2020;44:129-137) Keywords body mass index; indirect calorimetry; kcal per kg; obese patients; predictive equations; resting energy expenditure Clinical Relevancy StatementThe primary aim of this study was to establish a precise predictive method for estimating the energy needs of obese critically ill patients using body mass index (BMI) and actual body weight, based on the results of indirect calorimetry (IC) measurements. Following the stratification of the patients into groups according to their BMI, the resting energy expenditure (REE) of the patients was measured, and the resulting values were expressed as kcal/kg/d for each BMI group. Thus, a new modality of REE estimation was developed for obese patients, which might help clinicians when IC is not promptly available for day-to-day clinical nutrition practice.From the

The effect of age and body mass index on energy expenditure of critically ill medical patients

“…We have also observed that increasing BMI and female gender were independent determinants of an increase in EE adjusted for IBW after adjustment for several clinical factors. Our data regarding an increasing IBW-adjusted EE with increasing BMI are similar to the findings of others [ 25 , 26 ]. Gender difference in EE has been reported in critically ill patients by Drolz et al [ 27 ].…”

Agreement between equations-estimated resting metabolic rate and indirect calorimetry-estimated resting metabolic rate in low-income obese women

“…Regarding BMI, we recognize that the sample was composed by obese individuals including participants with a wide range of BMI, covering the 3 groups defined by the WHO to classify the degree of obesity. However, in our study, BMI did not influence either bias or weight-adjusted RMR, a finding corroborated by a study conducted in Brazil with a sample composed of obese but hospitalized individuals, which aimed to define the best RMR value in kcal/kg, considering the class and/or the BMI range of the patients and observed that there was no difference in RMR values between the different BMI classes in the fasting state ( 35 ).…”

Heat Flow Measurement of Human Skin Using a Calorimetric Sensor with a Programmable Thermostat. An Alternative to Climate Chambers

“…Both techniques -direct and indirect calorimetry -have been developed simultaneously, cross-validating mutually [7,8]. Nowadays, indirect calorimetry is the main technique used to express the energy cost of physical activities [9,10]. This energy is expressed in multiples of the resting metabolic rate (RMR), being the metabolic equivalent (MET) the unit used (1 MET corresponds to the consumption of 3.5 ml kg − 1 min − 1 of O 2 ).…”