Calorimetry in obese women: comparison of two different operating indirect calorimeters together with the predictive equation of Harris and Benedict

Abstract

In patients with obesity, it is important to know the exact metabolic function in order to assess balanced nutritional support, reducing the risks of the initial situation. For an adequate detection of the resting metabolic rate (RMR), commonly indirect calorimeters are used. In the present study, two different indirect calorimeters [an expiratory collection open-circuit system (Fitmate) and a ventilated open-circuit system (Quark RMR)], were correlated and analysed for better adequacy. The predictive equation of Harris-Benedict (HBE) was confronted with the measured RMR of the better evaluated indirect calorimeter. 42 obese women (age 55 ± 12 years and BMI 42.9 ± 6.8 kg/m2) were included in the study after selecting patients according to the predefined inclusion and exclusion criteria. Measurement durations of each 15 min were performed after an overnight fast with both calorimeters. Received values of Fitmate and Quark were compared while the calorimeter with the more reliable values was compared with the HBE. Significant correlations (P<0.001) between the devices were achieved, although a significant difference of 1,051 kJ/day (14.9%) between Fitmate (7,542 ± 1,230 kJ/day) and Quark RMR (6,491 ± 806 kJ/day) was detected. The mean calculated RMR of the HBE (7,181 ± 716 kJ/day), in comparison with Quark RMR was significantly different (P<0.001). The correlation of the two indirect calorimeters, their different functioning, led to significant differences between devices and RMR measurements. The HBE was found to overestimate the measured RMR of Quark RMR. Though the HBE was developed on lean subject, it cannot be considered as a reliable equation for obese subjects. © 2011 Springer-Verlag

Adequacy of basal metabolic rate prediction equations in individuals with severe obesity: A systematic review and meta‐analysis

“…Studies analyzing the validity of BMR predictive equations for use in individuals with severe obesity found that the equations performed differently. For the same equation, there are studies showing overestimation, [17][18][19][20] underestimation, [21][22][23][24] and adequacy in the BMR estimate. 25,26 Although most BMR prediction equations take anthropometric variables into account, they are frequently generated based on a weight range that does not include severe obesity, which may be the origin of their bias.…”

Estudio del gasto energético en una población adulta sana española: calorimetría indirecta "versus" modelos predictivos: propuesta de una nueva ecuación de estimación

“…La calorimetría indirecta es una técnica sencilla, inocua, rápida y relativamente económica que, en la práctica clínica, se considera como método de referencia (9) . La mayoría de los modelos de estimación del GER se desarrolla utilizando la CI como criterio de validación, si bien es cierto que la precisión de esta técnica puede verse afectada por cambios en el protocolo de medición o en el equipo (30,98,181,182) .…”

“…Algunos estudios han sugerido que la prolongación del tiempo de determinación podría mejorar la precisión y exactitud del GER medido cuando no existe un entrenamiento previo del sujeto, puesto que se ha visto una tendencia a la hiperventilación durante los primeros minutos del registro. Sin embargo, también se ha observado que con determinaciones demasiado prolongadas se pueden obtener lecturas erróneas debidas al agotamiento del sujeto (30,181,182,188) . Estos efectos se documentaron fundamentalmente con el uso de mascarillas.…”

“…No es probable que estas diferencias se deban a las características de la muestra estudiada, ya que, aunque la mayoría de los modelos se ha obtenido en sujetos sanos y con sobrepeso y obesidad, en nuestro estudio, como ya se ha comentado, se ha observado un porcentaje de masa grasa elevado. Otra posible justificación son las limitaciones discutidas en el epígrafe 7.1 a cerca del calorímetro utilizado: tiempo de determinación y uso de mascarilla (30,181,182) .…”

“…Sin embargo, no se debe pasar por alto las posibles limitaciones derivadas de la técnica calorimétrica y del modelo de calorímetro utilizado (30,181,182) .…”