What is the Respiratory Quotient (RQ) for fat metabolism?

The Respiratory Quotient (RQ) for fat metabolism is 0.7. RQ is a measure of the ratio of carbon dioxide produced to oxygen consumed during metabolic processes and varies depending on the type of substrate being oxidized for energy. For fats, the complete oxidation process uses a larger amount of oxygen relative to the amount of carbon dioxide produced, leading to a lower RQ value.

This value reflects that lipids require more oxygen for their oxidation relative to the amount of carbon dioxide produced. In contrast, carbohydrate metabolism typically has an RQ of 1.0 because carbohydrates produce equal amounts of CO2 and O2 during metabolism. The RQ for protein falls between that of fats and carbohydrates. Therefore, an RQ of 0.7 is specific to fat metabolism, indicating efficient metabolic conversion of fat into energy.