The oxygen and carbon dioxide sensors were calibrated before each measurement with the use of mixed reference gases of known composition. Subjects were admitted in the clinic at 8:00 a.m. after an overnight 12-h fast. The subjects rested comfortably in the recumbent position for 30 min in a thermoneutral environment and then had a clear plastic canopy placed over their heads. They were instructed to avoid hyperventilation, fidgeting, or falling asleep during the test. Oxygen consumption and carbon dioxide production were measured at intervals of 1 min during 30 min, and the mean of the last 20-min measurement period was used to calculate REE according to the Weir’s equation without using urinary urea nitrogen (15). The respiratory quotient was calculated as the ratio between the volume of CO2 expired and the volume of O2 consumed.
Anthropometry