Objective: To assess the validity and reliability of a hand-held indirect calorimeter.
Design: Resting metabolic rate (RMR) was measured on two separate mornings.
Subjects: A heterogeneous sample of 41 healthy adults.
Measurements: RMR using both a metabolic cart (Sensormedics 2900, SM-2900) and a hand-held indirect calorimeter (BodyGem, BG).
Results: There were no trial-to-trial differences in RMR measured by the BG (6756+/-163 vs 6697+/-163 kJ/day) or the SM-2900 (6400+/-163 vs 6396+/-167 kJ/day). RMR measured by the BG was significantly higher than that measured by the SM-2900 during both trials. In a sample of 10 subjects, the energy cost of holding the BG in position was determined to be (0.17+/-0.04 kJ/min, or 255+/-84 kJ/day). After applying this adjustment, the differences between systems were no longer significant during trial 1 (mean difference=101+/-67 kJ/day) or trial 2 (46+/-75 kJ/day). In overweight and obese individuals, RMR measured by the BodyGem was more accurate than that estimated by the Harris-Benedict equations.
Conclusion: The BodyGem provides valid and reliable measurements of RMR. The BodyGem produces significantly higher values than the Sensor Medics 2900 indirect calorimeter, with the increase largely due to an increased energy demand required to hold the BG in position.