Respiratory Quotient

The respiratory quotient can be represented as

RQ = V_CO2/V_O2

Where V represents ventilation of the given gas.

This ratio describes how many molecules of CO₂ are produced per molecule of oxygen consumed, which depends on the kind of fuel that is being burned. The more oxygen a molecule contains, the greater the amount of produced CO₂, and the higher the value. RQ also increases during hyperventilation or metabolic acidosis.

RQ_saccharides ~ 1

RQ_proteins ~ 0.8

RQ_lipids ~ 0.7

A typical RQ value for a subject with a Western diet is 0.8.

References

Boron, W. and Boulpaep, E., 2017. Medical physiology. 3rd ed. Philadelphia: Elsevier, pp.681.