Question

define respiration quotient.. and what is its value for fat?

Answer 1

The respiratory quotient (or RQ or respiratory coefficient), is a dimensionless number used in calculations of basal metabolic rate (BMR) when estimated from carbon dioxide production. It is calculated from the ratio of carbon dioxide produced by the body to oxygen consumed by the body. Such measurements, like measurements of oxygen uptake, are forms of indirect calorimetry. It is measured using a respirometer. The Respiratory Quotient value indicates which macronutrients are being metabolized, as different energy pathways are used for fats, carbohydrates, and proteins.[1] A value of 0.7 indicates that lipids are being metabolized, 0.8 for proteins, and 1.0 for carbohydrates. The approximate respiratory quotient of a mixed diet is 0.8.[1] Some of the other factors that may affect the respiratory quotient are energy balance, circulating insulin, and insulin sensitivity.[2]

Answer 2

Definition of Respiration Quotient:

Respiration Quotient is defined as ratio of value of carbon dioxide evolved to ratio of consumed oxygen during respiration. It can be represented as:

Respiration Quotient = $\bold{\frac{\text {Volume of Carbon dioxide evolved}}{\text {Volume of Oxygen consumed}}}$

The respiration quotient value for substrate depends upon its type. The RQ for fats is found to be less than one as it demands high amount of oxygen for its destruction. On contrary if you check RQ for carbohydrates it is one.