Proposed shorter duration protocols for measuring resting energy expenditure utilizing whole-room indirect calorimetry: Techniques and Methods

Background: Sixty minutes is currently the shortest testing duration for 24-h resting energy expenditure (24-h REE) utilizing whole-room indirect calorimetry. Objective: Show that recalculated 30-min extrapolated 24-h REE from previously published 60-min metabolic data are valid. Methods: Propane consumption linearity was determined through an 8-h combustion test. Thereafter, metabolic data for 24-h extrapolated ventilation rates of oxygen (VO₂; l/d), carbon dioxide (VCO₂; l/d), respiratory quotient (RQ; VCO₂/VO₂), and REE (MJ/d) from ten 60-min propane combustion tests were recalculated to reflect a 30-min testing duration. A similar analysis was performed utilizing data from 60-min subject metabolic measurements within a whole-room indirect calorimeter (4597 liters) specific for measuring resting energy expenditure (REE). Statistical (p < 0.05) comparisons between recalculated and original 60-min metabolic data were determined by SPSS (version 29). Results: Propane consumption during a combustion test was found to be linear for up to 8-h. Furthermore, no differences existed between propane stoichiometry and combustion for any of the extrapolated 24-h metabolic parameters when recalculated from 60-min propane combustion data to reflect a 30-min duration. Finally, similar results were obtained for all recalculated subject metabolic data. Conclusions: Recalculated extrapolated 24-h metabolic data derived from a 30-min testing duration appear to be valid. This suggests that whole-room indirect calorimetry could be an adjunct for various weight loss or other programs where accurate metabolic measurements are required.