Our bodies need the energy to function. That energy comes from the foods and beverages we consume.
Metabolism refers to the chemical processes by which our bodies convert the energy contained in our diets into energy useful to our cells. Our bodies then use that energy for various important purposes, including staying alive, being physically active, growing when we’re young, and having babies when we’re a bit older.
When we have excess energy, our bodies store it as fat. Metabolism is how an apple becomes a heartbeat or how a bagel becomes a marathon.
Metabolic testing measures your metabolic rate, simply the amount of energy your body uses over a given period. At the Kahm Center for Eating Disorders, we use a gold-standard method of measuring metabolic rate known as indirect calorimetry. The Kahm Center uses the same machines that are used by many of the best scientists in the world.
Indirect calorimetry measures how much oxygen you breathe in and how much carbon dioxide you breathe out and uses these measurements to calculate your metabolic rate. This is possible because the amount of oxygen you inhale and the carbon dioxide you exhale are proportional to the amount of energy your body uses. The underlying biochemistry is complex, but put simply, the chemical processes by which food and drinks are converted into bodily energy require oxygen, and carbon dioxide is a byproduct of these processes.
In fact, the reason why we need to breathe to stay alive is precisely because our bodies need oxygen for metabolism. Although there are plenty of online metabolic rate calculators, it is important to realize that they only provide rough estimates. To accurately calculate a person’s metabolic rate requires direct measurement of oxygen consumption and carbon dioxide production, and indirect calorimetry is the premier method for such measurements.
In addition to measuring oxygen consumption and carbon dioxide production, the metabolic testing machine used at The Kahm Center for Eating Disorders measures the three kinds of fuel our bodies use for energy: fats, carbohydrates, and proteins. If too little of the body’s energy comes from fats, it is possible the body is underfed or overfed. If the body is burning fats appropriately, this is usually a sign that the body is nourished enough to use fats for energy.
As metabolic testing is done (ideally) after an overnight fast, and our bodies burn through carbohydrates pretty quickly, the body should burn a low percentage of carbohydrates in this state. If this percentage is higher, it indicates that the body is not metabolizing carbohydrates efficiently, and there is an increased risk for insulin resistance, prediabetes, metabolic syndrome, etc. If the body is burning more proteins than it should, it is using its own proteins (muscles and organs) to fuel itself because the person is not eating correctly – this should be avoided at all costs.
Eating disorders tamper with the amount of energy from food available for metabolism. Eating disorders thus lead to disordered metabolism. Consequently, eating disorders can negatively affect various life-sustaining functions of the body and the amount of energy available for physical activity, growth, and reproduction.
Measuring the metabolic rate of a person with an eating disorder enables us to determine precisely how malnourished someone is and enables us to offer highly accurate meal plans to cure that malnutrition. Then, we can monitor how their metabolism improves over time and when it is restored to a healthy state.