The respiratory quotient is the ratio between the volume of carbon dioxide eliminated and the volume of oxygen inspired during respiration in a given period at standard pressure and temperature. The RQ value keeps changing depending on the respiratory substrate and their oxidation providing information about the substrate being respired. Protein, carbohydrates, and fats the macronutrients having the respiratory quotient between 0.7 to 1. Protein has an RQ of $0.8\mathrm{ }\mathrm{t}\mathrm{o}\mathrm{ }0.9\mathrm{ }\left(<1\right)$, carbohydrates have RQ as 1 and fats with RQ of $0.7$. The organic acids have $\mathrm{R}\mathrm{Q}\mathrm{ }>1$.