RER (Respiratory Exchange Ratio)

The Respiratory Exchange Ratio (RER) measures the ratio of carbon dioxide produced to oxygen consumed during metabolism. It provides insight into what fuel your body is using for energy: a lower RER (~0.7) indicates fat burning, while a higher RER (~1.0) suggests carbohydrate is the primary source. RER is useful in exercise testing and metabolic research to understand energy utilization and efficiency. It is determined through breath analysis, reflecting the balance of gases exchanged in the lungs related to cellular activity.