The Respiratory Quotient (RQ) is defined as: $RQ = \dfrac{\text{moles } CO_2 \text{ produced}}{\text{moles } O_2 \text{ consumed}}$. For glucose ($C_6H_{12}O_6$): $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O$, so $RQ = 6/6 = 1.0$. For lipids (more reduced), RQ ≈ 0.7; for organic acids (more oxidized), RQ > 1.