Feasibility, Reproducibility and Cold-Induced Energy Expenditure using Whole-Room Calorimetry in Adults and Children

Abstract Context To understand energy balance, whole-room indirect calorimetry (WRIC) allows for accurate measurement of energy expenditure (EE). Objectives To examine the relationship between cold-induced resting EE and brown adipose tissue (BAT) activity measured by MRI, evaluate WRICS performance and feasibility of use in children and adults. Methods The WRICS was equipped with a Promethion High-Definition Room Calorimetry system. Technical validation utilized N2 and CO2 gas infusions. Healthy adults (n=21) and children aged 8-17 years (n=17) attended two 4-hour WRIC visits (one week apart) and one MRI visit. Resting EE at 25°C (REE25) was compared between visits and to REE at 18°C (REE18). Recruitment and completion rates were examined. BAT activity was assessed by MRI as the decline in supraclavicular proton density fat fraction during 18°C cold exposure. Results Gas infusion testing confirmed high accuracy (RER=0.99; 95% CI 0.991–0.996). Study completion rates were high (Adults: 20/21; Children: 17/18). REE25 over a 10-minute period was consistent between visits (Adults: 1.68 ± 0.462 vs 1.66 ± 0.301 kcal/min, p=0.77; Children: 1.50 ± vs 1.58 ± 0.348 kcal/min, p=0.25). Cold exposure increased fasting EE by 0.21 kcal/min (adults) and 0.14 kcal/min (children). BAT activity was correlated with REE18 in adults (r=0.49, p=0.04). Conclusion WRICS use was feasible in adults and children. Changes in EE during cold (ie. cold-induced thermogenesis) were measurable and related to BAT activity, supporting the usefulness of this system in the assessment of EE in response to interventions in adults and children.