The Resting Metabolic Rate test (RMR) determines the amount of energy (calories) your body is using at rest. This measurement is made by analyzing the amount of oxygen your body uses and the amount of carbon dioxide your body produces. Almost all of the energy your body produces is created through aerobic (oxygen utilizing) metabolism. The oxygen is combined with carbohydrates and fats to make energy in your body’s tissues. This energy is used to keep your organs and tissues working properly. When carbohydrates and fats are broken down to make energy carbon dioxide is produced. The percentage of the energy created from carbohydrates and fats can be determined by measuring the carbon dioxide your body produces.

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What can a Resting Metabolic Rate Test performed?

The results of a Resting Metabolic Rate test can tell your doctor if you have an increased or decreased metabolism, and if your body primarily uses fats or carbohydrates for energy. This information can be used to determine the amount of calories you need to eat each day to maintain or lose weight. Dieticians often use this information when designing diets for their clients. The results may also indicate that you have a medical condition affecting your metabolism. Diabetes, under or over active thyroid, COPD, heart disease, mitochondrial disorders, and obesity are some common conditions that may alter your metabolism. Doctors may use the RMR to determine if certain medications are influencing your metabolic rate or if medical therapy is improving your metabolism.

How is a Resting Metabolic Rate Test performed?

During the Resting Metabolic Rate test you will be asked to relax in a chair while your oxygen uptake, carbon dioxide output, and electrocardiogram (EKG) are measured for 16 to 20 minutes. To measure the amount of oxygen your body is using and carbon dioxide it is producing, you will be asked to wear a face mask that covers your mouth and nose (similar to an airplane pilot’s mask). The face mask will not provide you with extra air, you will only be breathing from the air in the environment. Ten EKG stickers and leads will be attached to your chest to monitor your heart rate and rhythm. It is very important that you remain as relaxed as possible to get the most accurate results.

How should I prepare for a Resting Metabolic Rate Test?

Various activities may influence your metabolic rate and should be avoided before testing. For at least 5 hours before your test you should not eat or drink anything. You may drink water as needed. If you have a condition that requires you to eat frequently, such as diabetes, you may eat no less than 4 hours before testing. Exercise or physical labor should be avoided for 5 hours before the test. You will be wearing an EKG during the test, so be sure to wear clothing that allows access to your chest. Take your medications as prescribed unless directed otherwise by your doctor.