American Board of Surgery Qualifying Exam (ABS QE) Practice Test 2025 - Free Surgery Exam Practice Questions and Study Guide

An RQ, or respiratory quotient, is the ratio of carbon dioxide produced to oxygen consumed during metabolism. A value of less than 0.7 indicates a greater reliance on fat (lipid) metabolism rather than carbohydrates or protein. This is because fats yield fewer carbon atoms per molecule of oxygen consumed compared to carbohydrates, leading to a lower RQ value.

In metabolic calculations, an RQ less than 0.7 typically suggests that the body is in a state of starvation or prolonged fasting, where it predominantly breaks down fat stores for energy. This metabolic state can be critical for understanding a patient’s nutritional status and energy usage, especially in clinical settings.

Other options describe normal or typical metabolic processes. For instance, a balanced nutrition scenario or predominance of carbohydrate metabolism would result in RQ values closer to 1.0 or around 0.8, indicating a mix of substrates being utilized rather than a primarily lipid-based metabolism. Therefore, the indication of lipid metabolism offered by an RQ less than 0.7 is an important concept in assessing metabolic states and energy utilization.