The respiratory quotient (RQ) is used in the calculations of basal metabolic rate (BMR). It is the ratio of the volume of carbon dioxide produced by the body to the volume of oxygen consumed by the body in respiration over a period of time. It depends on the type of respiratory substrate used during respiration. RQ of fat is about 0.7. RQ of carbohydrate is 1. RQ of organic acids is above 1. RQ of protein is 0.9. RQ value gives information about the source of energy an animal is using.