The present disclosure pertains to a system for metabolic measurements, the system comprising: a metabolic monitor configured to determine first concentration measurements of O2 and CO2 in a portion of gas exhaled by a subject during one or more breaths; and determine a first rate of O2 consumption (VO2) and a first CO2 volume production (VCO2) of the subject during the one or more breaths based on the determined first O2 concentration and the determined first CO2 concentration; a CO2 monitor configured to determine second CO2 concentration measurements in the exhaled gas during the one or more breaths; and determine second CO2 volume production (VCO2) of the subject based on the measured second CO2 concentration; and processors configured to determine a correction factor based on the determined first VCO2 and the second VCO2; and determine a corrected first VO2 using the correction factor and the first VO2.