Indirect calorimetry

Advances in health care have provided modern tools to get better insights into your health. Your doctor may recommend performing an indirect calorimetry test to get a better understanding of how your body uses oxygen and expends energy when resting.

By gauging your oxygen use and carbon dioxide release, indirect calorimetry analysis provides valuable insights into your metabolism, including how many calories you burn when resting.

Using an indirect calorimetry test, your Advocate specialist can work with you to personalize your nutrition to meet your body’s energy needs.

What is an indirect calorimetry test?

Indirect calorimetry is increasingly becoming an integral part of health assessments. It's considered the gold standard for:

• Determining energy use
• Respiratory gas analysis
• Calculating how many calories your body uses while resting

To perform this test, your Advocate clinician uses a machine that has a breathing mask on it. This indirect calorimetry machine evaluates carbon dioxide production and oxygen use to calculate how much heat your body produces.

This test provides unique information, is noninvasive and may be combined with other methods to determine energy output. It’s commonly used to understand metabolic diseases, such as Type II diabetes, heart disease and lung disease.

Indirect calorimetry is often used by athletes to determine calorie needs for both resting and during physical exercise. It can also help trainers and doctors adjust nutrition plans to meet calorie needs.

The indirect calorimetry test process

An indirect calorimetry test is performed using a metabolic cart, which consists of a mask and blood pressure cuff connected to a computer. The setup of the test depends on the purpose of having the test done.

If your doctor is checking for “resting conditions,” the test would take about 10 minutes. You will be asked not to participate in any physical activity before the test. It is also recommended to not eat or drink any caffeine or other stimulants.

For exercise testing, a mask is worn during a physical activity, such as jogging on a treadmill or riding a stationary bike. This test is performed over two 10-minute periods. This test is commonly used to check oxygen intake and carbon dioxide released. You might be given this test to check for heart and lung conditions.

Applications of indirect calorimetry

Indirect calorimetry has a broad spectrum of uses, including:

• Medical research
• Weight management
• Optimizing physical training programs
• Managing lung diseases

This test can also measure metabolism, which is valuable to evaluate metabolic disorders, nutritional needs and the effects of treatments. Understanding your metabolic rate can help your Advocate specialist improve treatment or recommend changes to your diet.

Direct vs. indirect calorimetry

You may hear the term direct calorimetry used with indirect calorimetry. One difference between direct vs. indirect calorimetry is the complexity of the testing procedures.

Direct calorimetry is more complex and may take longer – sometimes up to several hours. It’s performed using a calorimeter chamber. A direct calorimetry test also measures oxygen use and carbon dioxide production. It also measures heat released directly from the body.

Using indirect calorimetry to personalize health strategies

Everyone’s body is unique and has different health needs. Indirect calorimetry tests can give valuable insights to your doctor so they can personalize your care.

Using nutritional planning based on calorimetry, your Advocate specialist can recommend precise daily calorie needs for weight loss, weight gain or weight maintenance. It also allows them to adjust treatment plans for heart and lung conditions or detect potential health issues.