What Is Your Respiratory Exchange Ratio?

woman holding hands over abdomen

Breath analysis is emerging as a safe, effective, and noninvasive means of testing and monitoring metabolic health. Key metrics calculated from markers in the breath can be used to ascertain how efficient our bodies are at conducting daily functions. The Respiratory Exchange Ratio (RER), for example,  is a particularly valuable metric that can provide us with a wealth of insights into how our bodies process food–a key consideration in disorders like type 2 diabetes. Let’s learn more about the RER and how it can be used to tailor treatment plans for certain metabolic disorders. 

Understanding the Respiratory Exchange Ratio (RER)

RER and Indirect Calorimetry

The Respiratory Exchange Ratio is a form of indirect calorimetry–a method which uses gas exchange measurements to evaluate how and what types of fuel the body processes under specific scenarios.

The RER is calculated by comparing the amount of carbon dioxide (CO2) produced to the amount of oxygen (O2) consumed. Different fuel sources—such as carbohydrates, fats, and proteins—yield different ratios of CO2 production to O2 consumption, allowing us to infer the primary substrate being oxidized for energy.

Carbohydrates: when carbohydrates are the primary fuel source, they are metabolized through glycolysis and the citric acid cycle (also known as the Krebs cycle) in the presence of oxygen. This metabolic pathway produces more CO2 relative to the amount of oxygen consumed. As a result, the respiratory exchange ratio approaches 1.0 when carbohydrates are the predominant energy source.

Fats: conversely, when fats are the primary energy source, they undergo beta-oxidation to produce acetyl-CoA, which enters the citric acid cycle for further oxidation. Fat metabolism generates less CO2 per molecule of oxygen consumed compared to carbohydrates. Therefore, the RER decreases and approaches 0.7 when fats are the predominant fuel source.

Proteins: protein metabolism also contributes to energy production, particularly during prolonged fasting or low-carbohydrate diets. The respiratory exchange ratio for protein oxidation falls between that of carbohydrates and fats, typically ranging from 0.8 to 0.9.

How RER Predicts Metabolic Dysfunction

Aside from offering insights as to the type of fuel source your body favors, the respiratory exchange ratio can be used as a general marker of overall metabolic health. In general, a person who is metabolically healthy will have an appreciable spike in their RER following a meal, regardless of the substrate (i.e. carbs vs protein). This spike indicates that their cells are able to fully access and oxidize the nutrients provided by the meal.

On the other hand, individuals who exhibit a lower or plateaued respiratory exchange ratio after eating may not be efficiently processing energy from the food they eat. Metabolic dysfunction is characterized by an inability to metabolize glucose. Instead, the body favors lipid storage, which increases the presence of fat within our muscles and organs. After eating, a person with compromised metabolism (as in the case of insulin resistance) will begin to accumulate lipids instead of breaking down the glucose energy readily available. This will be reflected in their final respiratory exchange ratio. 

What Are Common Symptoms of Metabolic Dysfunction?

The body’s metabolism governs a wide array of functions within the body. As such, dysfunction can manifest in equally varied ways. In general, however, some common symptoms of a metabolic disorder include:

  • Fatigue
  • Abdominal obesity
  • Loss of appetite
  • Headaches
  • Nausea/vomiting
  • Muscle pain/weakness

Measuring RER via PNOĒ Breath Analysis

Breath analysis is an important part of a functional medicine treatment program. At Balanced Body Health & Wellness, we utilize the PNOĒ platform, which presents your information in a final report tailored to your specific wellness goals (longevity, performance, or weight loss).

You will be fitted with a mask and asked to breathe normally for around ten minutes. In this short period, the PNOĒ analyzes 23 biomarkers used to evaluate metabolism, heart and lung health, fuel efficiency, and even your biological age. 

Your provider will go over your report with you in detail. Along with your medical history and physical, this information will be integral in developing your treatment program. Knowing how well your body absorbs nutrients via your respiratory exchange rate, for example, will be an essential component of your dietary, lifestyle, and exercise modifications. 

Metabolic Testing in Omaha

If you are experiencing symptoms of metabolic dysfunction in Omaha and the surrounding areas, Balanced Body Health & Wellness is here to help you feel better. As a functional medicine provider, we utilize a variety of holistic techniques to ensure your wellness plan is tailored to your individual needs. This includes PNOĒ breath analysis, which is accurate, non-invasive, and affordable. Call or go online today to schedule your free 15 minute discovery call to see if this test is right for you. 

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