Metabolic rate testing · St. Louis
Metabolic rate and energy
Your resting metabolic rate can be measured directly with indirect calorimetry: you breathe normally for about ten minutes while oxygen use and carbon dioxide output are recorded. The result is your resting energy expenditure and the respiratory quotient, which shows the fuel you burn at rest.
Most calorie targets are produced by an equation that guesses your metabolic rate from your age, sex, height and weight. It is possible to measure it instead.
How accurate is a calculated metabolic rate?
A predictive equation takes population averages and applies them to you. That works reasonably for the average person and badly for anyone who is not — which includes people with a lot of muscle, people who have lost a lot of weight, people with thyroid disease, and older adults with reduced lean mass.
Indirect calorimetry measures it directly. You breathe normally for around ten minutes while oxygen consumption and carbon dioxide production are recorded, and from those two figures the device calculates resting energy expenditure and the respiratory quotient.
What does a metabolic rate test show?
Resting energy expenditure
The energy your body uses at rest, which is the large majority of what most people use in a day. This is the number a calorie target should be built on, and it is the number most often wrong when someone says a diet stopped working.
Respiratory quotient
The ratio of carbon dioxide produced to oxygen consumed. Because burning fat and burning carbohydrate consume oxygen and release carbon dioxide in different proportions, this ratio indicates which fuel your body is predominantly using at rest. A lower value indicates fat is the predominant fuel; a higher value indicates carbohydrate.
Neither number is good or bad on its own. Both are useful because they can be repeated, and because they explain results that otherwise look like a failure of willpower.
Why is metabolic rate read alongside body composition?
Resting energy expenditure is produced overwhelmingly by lean tissue, so the measurement is only interpretable alongside body composition. And fuel use at rest sits directly downstream of insulin resistance, which is measured in the same visit.
How do you prepare for a metabolic rate test?
The measurement is taken at rest after an overnight fast, with no caffeine and no nicotine. Food, coffee, a cigarette or a brisk walk from the parking lot will all change the result. Full preparation instructions.
If you are a clinician: the same subject written for the person ordering the test is at the full test description.
Talk to someone about testing
Tell us what you are trying to find out and we will explain which Measura assessments answer that question, what each one involves, and how the results are reviewed with a clinician.
4477 Woodson Rd, Suite 201, St. Louis, MO 63134. Monday to Friday, 9:00 a.m. to 5:00 p.m. Please do not send symptoms, diagnoses or images through a web form — a website form is not a secure medical channel. Send your name and number and we will call you back.
Frequently asked questions
Is my metabolism really slow?
It is a testable claim rather than a belief, and the answer is often not what people expect. Measured versus estimated metabolic rate.
Why did my weight loss stall?
Resting energy expenditure falls as lean mass falls, so a target set at the start of a program may no longer be right. Measuring resolves it. Why the estimate drifts after weight loss.
How long does the measurement take?
About ten minutes of quiet breathing. What the appointment feels like.
Do I need to fast?
Yes, overnight, with water allowed. Preparation instructions.
What is meant by metabolic rate?
Your resting metabolic rate, or resting energy expenditure, is the energy your body uses at rest. For most people it is the large majority of what they use in a day, which is why it is the number a calorie target should be built on. It is produced overwhelmingly by lean tissue, so it has to be read alongside your body composition.
How can I check my metabolic rate?
Measure it with indirect calorimetry instead of estimating it from an equation. You breathe normally for about ten minutes while your oxygen use and carbon dioxide output are recorded. From those two figures the device calculates your resting energy expenditure and respiratory quotient. The test is done at rest after an overnight fast, with no caffeine and no nicotine beforehand.
What is a good metabolic rate?
Neither result is good or bad on its own. Resting energy expenditure only means something in relation to how much lean tissue is producing it, and the respiratory quotient simply shows whether fat or carbohydrate is your main fuel at rest. Both are useful because they can be repeated and because they explain results that otherwise look like a failure of willpower.
Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP, medical director of Measura. Last reviewed .