According to RER guidelines, what does a value of 0.85 indicate?

The value of 0.85 in the context of the Respiratory Exchange Ratio (RER) indicates that carbohydrates and fats are being utilized for energy at approximately equal rates. The RER is a measurement used to estimate the type of substrate (carbohydrates or fats) being used for energy during metabolism, calculated as the ratio of carbon dioxide produced to oxygen consumed.

An RER of 0.85 specifically suggests that there is a mixed substrate utilization. When the value is closer to 0.7, it typically indicates a higher reliance on fats for energy, while values approaching 1.0 are indicative of a greater reliance on carbohydrates. Therefore, an RER of 0.85 reflects an efficient balance between these two energy sources, showing that both are being metabolized simultaneously to match the energy demands of the body.

This understanding is crucial in the fields of exercise physiology and nutrition, as it can impact training and dietary recommendations based on an individual’s metabolic responses during different forms of exercise.