Define RQ. What is its value for fats?

The respiratory quotient (RQ) is defined as the ratio of the volume or moles of carbon dioxide produced to the volume or moles of oxygen consumed by an organism during cellular respiration

RQ provides insight into which macronutrients are being oxidized for energy and is measured using respirometry under steady-state conditions

The RQ value for pure fat oxidation is approximately 0.7, indicating that more oxygen is required relative to carbon dioxide produced when metabolizing lipids

• Specific fatty acids yield slightly different RQ values

  • palmitic acid oxidation (C₁₆H₃₂O₂) produces 16 CO₂ per 23 O₂ for an RQ of about 0.70

  • triolein yields an RQ of approximately 0.71

RQ values between 0.7 and 1.0 indicate mixed substrate utilization, with values closer to 0.7 signifying predominant fat metabolism and values closer to 1.0 indicating predominant carbohydrate metabolism