Respiratory Quotient (i.e., Respiratory Exchange Ratio): What Is It and How Is It Connected to Metabolism?

A respiratory quotient (RQ) is a measurement of the relative rates of oxygen and carbon dioxide transpired in an organism during normal metabolism. It can be calculated by dividing the partial pressure for oxygen in millimeters of mercury (mm Hg) by carbon dioxide in mm Hg. The respiratory quotient is a measurement of the metabolic processes associated with respiration.

Breezing Pro for RQ measuring and other metabolic rates

While it’s possible to measure the carbon dioxide in the blood as a gas, the measurement of carbon dioxide in body tissue is complicated, as tissues contain water. In addition, it’s also difficult to separate carbon dioxide from other gases.

RQ Range and What It Means

In people on a high protein diet, respiratory quotients are high because they metabolize more protein for energy than fat. At rest, respiratory quotients usually range from about 0.7 to 1.0.

metabolic rate analyzer

RQ = 1

An RQ of 1 indicates that a body’s primary source of utilization is carbohydrates. The carbohydrates are completely oxidized, and an equal amount of CO2 and O2 are consumed.

The number of carbohydrates oxidized per mole of oxygen consumed is known as the coefficient of carbohydrate oxidation. Several factors affect this value, including temperature, reaction pathway, and molecular weight of the molecule being oxidized.

Additionally, there are several types of respirometry instruments used in measuring RQ, with significant differences in measurement methods depending on whether they measure partial pressures or concentrations.


An RQ of less than 1 indicates that a body’s respiration is using fats as substrate. The body is using much fat or protein for fuel. Another way to look at this is that the body’s cells are not getting enough nutrients (e.g., carbohydrates) to work well, and thus they must use other nutrients (i.e., fats and proteins) to maintain normal function and performance in the absence of sufficient glucose (sugar) in the blood.

Buy Breezing Authentic Weight Management Devices for Accurate Metabolic Measurements

If you want accurate RQ, REE, and RMR readings, you must need devices that measure precise metabolic rates. This helps you track your weight management plan with ease. Breezing offers a range of mobile metabolic rate analyzers that you can wear and breathe into for 10 minutes and measure your RQ level.

The company also offers metabolism tracking devices and FDA-approved weight-loss devices. Contact us today to learn more about our products.

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