NCSF Sport Nutrition Specialist Certification Practice Test – Complete Exam Prep

A respiratory quotient (RQ) of 0.7 during aerobic exercise indicates that the body is primarily utilizing lipids (fats) as its main energy source. The RQ is calculated by taking the ratio of carbon dioxide produced to oxygen consumed during metabolism. Each macronutrient has a different RQ value:

- Lipids have an RQ of approximately 0.7, meaning they are predominantly being oxidized for energy.

- Carbohydrates, on the other hand, have a higher RQ of around 1.0, as they produce more carbon dioxide relative to the oxygen consumed.

- Proteins generally have a more variable RQ, often averaging closer to 0.8, depending on the type of protein and the metabolic state of the individual.

During low to moderate intensity aerobic exercise, the body tends to rely more heavily on fat stores for energy, which is reflected in the low RQ value. This metabolic shift generally occurs because fats provide a more substantial energy yield per gram compared to carbohydrates, making them more efficient during prolonged activity when oxygen is plentiful.