Respiratory quotient (RQ) is the ratio of the volume of carbon dioxide produced to the volume of oxygen consumed during cellular respiration. It is a measure of the type of fuel being metabolized by an organism.
The respiratory quotient of fat is approximately 0.7. This means that for every molecule of oxygen consumed during the metabolism of fat, approximately 0.7 molecules of carbon dioxide are produced. This indicates that fat is a less efficient source of energy compared to carbohydrates, which have an RQ of around 1.0.