Metabolic Testing Is All The Rage—But Can It Actually Help With Weight Loss?

Here's the thing: It's actually possible that your metabolism is just different, (meaning, slower) than your friends. In case youve forgotten from your high school biology class, metabolism is the rate at which your body burns calories for energy. And its a complicated process that also involves your oxygen intake and carbon dioxide output (a.k.a. your breathing), the Mayo Clinic explains.

Everyone's metabolism is different, and those differences are generally based on height and weight, your activity levels, and the biggie, genetics. But knowing how your metabolism operates could be the key to losing weight more successfullyalthough getting deets on your metabolism is not as simple as, say, taking your temperature or timing how fast you can run a mile on a treadmill.

Understanding how your metabolism works requires specific kinds of testing, as well as a qualified professional to interpret those results and translate them into a customized weight-loss program. Interested in learning more? Here's all the info from experts on what various types of metabolic testing involve, plus who should be getting tested.

First: What does a metabolic test reveal exactly?

Metabolic testing measures how many calories a person burns while at rest (also called resting metabolic rate, or RMR), according to the Center For Metabolic and Weight Loss Surgery at Columbia University.

RMR tells you what your basic daily caloric needs are for maintaining your weight if you sit around doing nothing all day. Knowing that rate paves the way to more accurately calculating how many calories you would need to consume per day to lose weight.

In other words, if youre dieting constantly but not getting the results youre hoping for, metabolic testing could help you understand your body better and lead to more weight loss.

A metabolic test can be very helpful for weight-loss goals because it is a fairly accurate way to know how many calories you need [to lose weight] while still allowing your body to function properly, says Joanne Donoghue , PhD, exercise physiologist and associate professor at NYIT College of Osteopathic Medicine.

Striking that just-right caloric balance is important, says Donoghue. On a very basic level: Consume more calories than your body requires at rest and you gain weight; too few calories, and your body may slow down its metabolism in order to conserve energy, which can also lead to weight gain.

If your metabolism seems like one big mystery, thats because it typically is for the average adult who hasn't done a metabolic test. But a metabolic test gives you actual numbers to work with so you arent just guessing at your caloric needs.

What are the different types of metabolic tests out there?

There are a few different ways to approach metabolic testing, but not all of them are the best choiceor even availablefor the average person. These are the most common metabolic tests and what they involve:

Direct calorimetry : This measures your body heat to determine the number of calories you burn. Typically, you would sit inside a special chamber for about an hour while the machine does its thing. Its basically considered the gold standard for RMR testing in terms of accuracybut its so expensive and high-tech that its very rarely used outside of a research or laboratory setting.

Indirect calorimetry : This measures how much oxygen you consume compared with the amount of carbon dioxide you breathe out. Its more portable, affordable and accessible than its counterpart, meaning this is likely the option youll be given if youre signing up for testing through your gym. You simply wear a mask or lie down under a hood while a machine takes your oxygen and carbon dioxide measurements for about 15 to 20 minutes. Even though its lower-tech, Donoghue says its still pretty accurate.

VO2 max test : If you are an athlete who wants to optimize caloric intake or lose weight, you may also benefit from something called a VO2 max test, which measures your bodys ability to consume oxygen. For this test, you wear a breathing mask while running on a treadmill to determine how much oxygen you consume when youre running at your hardest. Its one of the most accurate tests for cardiorespiratory fitness, according to the University of Virginia School of Medicine .

If youre not an athlete, you should probably stick with just testing your RMR using one of the first two options.

How accurate is metabolic testing?

In general, metabolic testing via indirect calorimetry is a reliable way to obtain information about your body that you might not otherwise have. But its also important to remember that a lot of the testing accuracy comes down to the equipment being used and whos doing the testing and interpreting the resultsmore on that in just a sec.

Be wary of body composition tests that claim to predict your RMR and stick with indirect calorimetry, when possible. There are body composition tests like hand-held dynamometers or scales that try to predict RMR, [but those] are prediction values and some more accurate than others, Donoghue explains. Indirect calorimetry, when done correctly, has the least amount of error."

A 2017 review of data in the Indian Journal of Endocrinology and Metabolism concluded that while predictive methods of testing are questionable, indirect calorimetry is a valuable resource for calculating nutrition needs and managing chronic health conditions.

If I want to get my metabolism tested, where can I do it? How much does it cost?

Originally, getting a metabolic test was a pretty exclusive thing, offered only at hospitals and weight-loss clinics. Now, its much more accessible, with many gyms and fitness centers, sports medicine facilities, and dietitian offices offering the testing.

Of course, thats a buyer beware situation. Private- or corporate-owned facilities, like your local health club, may not be using the most accurate equipment (or keeping it running smoothly). Dont be afraid to ask questions about the equipment being used and the professional guiding you through the test. Ideally, it should be a certified personal trainer, registered dietitian, or an exercise physiologist.

As far as the expense goes, Donoghue says a typical price range is $75 to $100.

Anything I need to know before going in for a metabolic test?

Theres not much you need to do to prepareexcept fast the morning of your test, and not just from food.

Restrain from having any caffeine, alcohol, or nicotineand dont exercise, advises Donoghue. If youre tested within a few hours of any of these, the accuracy of your test will be greatly affected. Beyond that, because its your resting metabolic rate thats being tested here, theres no pressure on you to do much of anything (basically, you get to chill).

One final thing: Remember that your results are just numbers, and without a plan in place to do something based on those numbers, it wont change your weight-loss results.

The bottom line: Metabolic testing can definitely give you insight into how many calories your body burns at rest and how to create a calorie deficit. But shelling out for a metabolic test is only step one; step two is working with a personal trainer or registered dietitian to create a personalized caloric goal and fitness routine for weight loss.