Why Measuring Your Body Fat Percentage with BodyMetrix Ultrasound is Better Than Other Methods

Cropped image of woman feet standing on weigh scales, on gray background. A tape measure in the foreground

People often get attached to a number they want to see on the scale, but that number doesn’t actually tell us what’s going on in their bodies. As a trainer, you could have two clients who both stand at five feet, four inches tall and weigh 130 pounds. Yet if one of them has 10 percent body fat and the other has 20 percent body fat, they’re going to look very different. So what good is that number?

It means little without measuring someone’s body fat percentage. Knowing your clients’ body composition—including how much fat they have and how much it weighs—helps you focus in on exactly how much body fat they need to lose, and it gives you a way to measure progress that is much more specific and interesting than the scale.


Body Fat Testing Methods

As with other fitness assessments, there are various ways to test your body fat percentage, and some are far more accurate than others. It’s important to consider the options when choosing the one that’s right for your clients in terms of accuracy, affordability, and accessibility.

Circumference Measurements

Although this is fairly easy to do and it may help someone see progress, particularly if he or she is significantly overweight at the beginning of his or her fitness journey, measuring someone’s waist, hips, and other areas can hardly be considered a way of testing for body fat percentage. Formulas that use measurements along with your height and weight are inaccurate: they can’t account for the density of the bones and muscles, which are also part of what you’re measuring when you wrap that tape measure around your thigh or bicep.

Skinfold Measurements

This technique is commonly used among personal trainers because skinfold calipers are relatively inexpensive and easy to have on hand. Measurements are taken by pinching the skin in the device at specific sites on the body. There is quite a bit of room for error (allowing for a body fat percentage difference of as much as five percent); the accuracy depends largely on how skilled the person is at administering the test. If two different people do your skinfold measurements, you might get two different results based on the tester’s ability. Furthermore, there are various formulas used with skinfold measurements, so you might see different results based on which formula your tester uses.

Hydrostatic Weighing

When perfectly administered, this is a pretty accurate way of testing body fat. However, it’s not a test that’s readily available at your local gym, and you have to hold your breath while your body is completely underwater—which, if you’re not a fan of swimming, might not be the way you want to spend your time.

Bioelectrical Impedance Analysis (BIA) and Bioimpedance Spectroscopy (BIS)

Both of these methods use electrical currents to determine your body composition (the electricity moves through different types of tissue at different speeds). There are a wide variety of BIA devices, some of which can be purchased by consumers and others that are available at medical facilities and universities. The accuracy varies from device to device, and your results can be impacted by hydration, food intake, and more. BIS is typically only available in university and medical settings. It’s more accurate than a BIA device you might have purchased for use in your gym or training facility, but it’s prone to a similar rate of error as we see with the high-end BIA devices found in medical and research settings.

Air Displacement Plethysmography

ADP is much like hydrostatic weighing, except instead of being submerged in water, you sit in a chamber (like the Bod Pod) as the air pressure changes around you. It’s quick and accurate, but not easily accessible for most of us and it’s usually expensive.


Dual-energy x-ray absorptiometry uses x-rays to scan your body for bone density, lean mass, and body fat. It takes about 10 minutes. Though it offers accurate results, it can only be done in medical or research facilities and tends to be expensive.


For more than fifty years, ultrasound has been used to measure body fat—yet for some reason, it’s still not the first idea people think of when they want to learn more about their body composition! Ultrasound has proven to be as accurate as other methods, and it allows us to measure muscle and bone thickness as well as assess body fat. Your results won’t be influenced by your hydration level at test time, or whether or not you’ve recently exercised. The device is portable, giving it a distinct advantage over hydrostatic weighing and DXA, for example. Ultrasound is safe and the test is easy and comfortable.

Using BodyMetrix Ultrasound to Test Body Fat

At Elite Body Data, we use the BodyMetrix to test body fat. This specific device has been studied in comparison to other body fat testing methods and has been proven effective and reliable. Furthermore, while you or your clients are always welcome to visit us at the lab, and we could test your body fat on the same day we test your VO2 max, the BodyMetrix allows for easy testing in the comfort of your home or your gym, as well.

The reasons to use ultrasound are basically outlined in the drawbacks of other body fat testing methods, as mentioned above:

  • Ultrasound is safe and comfortable.

  • It is more accurate than certain other methods.

  • It gives you a clear picture of your muscle mass and body fat percentage.

  • Your results won’t vary based on hydration, food intake, or recent activity.

  • There’s less room for tester error than with a skinfold caliper, for example.

  • It’s affordable, allowing for repeat testing to measure progress on an ongoing basis.

  • We can bring it to you, which makes it as easy as possible to make an appointment.

Preparing for a body fat test using ultrasound is easier than almost any other fitness test. There’s nothing you need to do or not do! Simply schedule an appointment at the lab or invite Elite Body Data to your home and you’re ready to go. If you’re a trainer, we can come to your facility and test your clients there.

After the test, your clients receive a profile that outlines the following and more:

  • Your total body fat percentage, as well as how much of that is essential and how much is excess.

  • Percentage of lean mass and water.

  • Cross-sectional scans showing fat and muscle distribution on specific areas of your body.

  • Health recommendations and relative risk of certain diseases.

  • The thickness of the fat on specific areas of your body.

What to Do Next

Armed with accurate knowledge of the make-up of your clients’ bodies, you can design an appropriate fitness and nutrition program for each of them. Not only do all of your clients have different goals, they all have very different bodies; one approach isn’t going to work for everyone, and the best trainers get as specific as they possibly can for each client. Whether or not a client’s weight changes, you’ll be able to track the specific changes to his or her body fat and lean muscle percentages as they follow your program and see that what they’re doing is working. If it’s not, you can make adjustments to get them back on track.

Testing the resting metabolic rate (RMR) goes hand-in-hand with body fat testing. The RMR test gives your clients the number of calories they need to consume every day to support their bodies at rest. You can add the calories they burn during activity to determine how much they need to eat every day to meet their goals. Without this number, you’re forced to do a lot of guessing that may derail their progress.

Anyone who tests their body fat (or does any other fitness assessment) should do so on a somewhat regular basis. The numbers will change as they get more fit and make lifestyle changes. Encourage your clients to keep testing as they progress through their fitness journey. Not only does this give them peace of mind that what they’re doing is giving them results, it also gives you the most up-to-date stats for each person so you can continually adapt their programs—so they can keep seeing results and avoid the dreaded plateau.

Individuals can book individual tests or monthly memberships, which helps keep them on track with regular tests. As a trainer or leader of a fitness facility, our Gold and Platinum memberships allow you to test multiple clients on a monthly basis. This is a great way to add value to your training service and helps ensure your clients actually follow through with getting the test, instead of making it something they intend to do but never get around to.

Contact Elite Body Data to learn more about body fat testing and how we can help your clients see results—which will help you build your training business. We’re happy to answer any questions you might have about the BodyMetrix or any other tests we offer. We look forward to meeting you!


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