Topical Area: Methods and Protocols
Objectives : Standard procedures to estimate resting energy expenditure (REE) using indirect calorimetry are time-consuming, and may be unnecessary. Indeed, the guidelines recommend a pre-test resting period of 30-minutes, followed by a 5-minute stabilization period, and then waiting until the first steady state period (SS), defined as a 5-minute period with a coefficient of variance (CV) of < 10% for VO2 and VCO2, to estimate REE. The aim of the study was to evaluate alternative procedures for estimating REE in adults with overweight and obesity.
Methods : Indirect calorimetry was performed in 37 adults enrolled in a weight loss trial using a metabolic cart (Quark RMR, COSMED). The volume of oxygen (VO2) and volume of carbon dioxide (VCO2) were collected every 10 sec for ≥20-minutes following pre-test resting (10-mins) and stabilization (5-mins) periods. The measurement period was segmented into five-minute (REE6-10, REE11-15, REE16-20, and REE21-25) and rolling (REE6-15, REE6-20, and REE6-25) periods, and VO2, VCO2, and CV were calculated for each period. REE was calculated using standard criteria (REESS). Alternative SS periods of 3- and 4-minutes (REE3 and REE4) were applied to those who did not achieve REESS. REESS estimates were compared to the other estimates of REE using paired t-tests.
Results : Participants were 51±14SD yo, primarily women (78%), and had a BMI of 35.4±5.5SD kg/m2. REESS was achieved by 81% (n=30) of all participants, and 54% (n=20) achieved REESS during the first 5-minute period (REE6-10) following stabilization. Applying REE3 and REE4 criteria, those who did not reach REESS increased to 92% (n=34). There were no significant differences between REESS, and REE3 (P=0.21), REE4 (P=0.40), REE6-10 (P=0.38), REE6-15 (P=0.15) or REE6-20 (P=0.05).
The majority of adults with overweight and obesity met the standard criteria for SS following a reduced pre-test resting period. However, the non-significant difference between REESS and rolling averages suggest the standard criteria may be unnecessary in a group setting.
Funding Sources : American Heart Association