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How Do DEXA, Underwater Weighing, Bod Pod, Smart Scales, and Calipers compare to Spren Body Composition Imaging?
Spoiler alert: the only truly accurate method of measuring body fat is to do it post-mortem. All body fat analysis methods, even DEXA, which is often considered the “gold standard” approach , calculate various metrics and plug these into standard equations to determine body composition results.
So, all accessible body composition analysis methods will never be 100% accurate—it’s just not possible. However, some methods are more accurate than others and provide further insights.
In this article, we explain how to measure body composition using the most common methods. We’ll highlight the pros and cons of each method, how they work, and more. But first, a quick definition of body composition.
Body composition provides us with a more accurate picture of precisely what our bodies are made up of.
This has very quickly become an important—and preferred method—of determining the desirable body weight of healthy adults and athletes .
For example, unlike traditional weight measurement tools, such as a set of scales or standard BMI equations, body composition tells us percentages of fat, muscle, and bone in the body.
These insights allow us to go beyond the scale, assessing how healthy an individual actually is.
In total, there are six main body composition analysis methods, including Spren. These are as follows:
We’ve provided you with an accuracy comparison table below—it includes key measurements for each method, alongside the average cost of a scan.
How it works: A Dexa Scan, also known as dual-energy x-ray absorptiometry, uses x-rays to calculate the distribution of lean muscle mass, fat mass, bone, and water in the body. During the scan, two x-ray beams—of which are very safe—pass through bodily tissues. The varying energy absorption allows practitioners to measure body composition, including fat distribution, accurately.
And as already mentioned, it’s often considered the “gold standard” body composition analysis tool, adopted by many healthcare professionals and commonly used in a clinical setting .
How it works: A pair of skinfold calipers are used to measure the thickness (mm) of the skin at various sites on the body, including the abdominal, thighs, triceps, and chest).
The skinfold test has been around for decades, and although it’s relatively easy to do, results can be inaccurate and present several downsides. For example, the test relies on two predictions to provide results, reducing validity .
We cover more of the downsides, alongside a few benefits below.
How it works: The participant sits down on a scale while submerged in a tank of water. It’s important to exhale fully to reduce error and ensure accurate results. The test is usually repeated three times for reliability.
Underwater weighing relies on the Archimedes principle—which states that when your body is completely submerged, the volume of fluid displaced is equal to the volume of the body .
You are also weighed before completing the test. Test administrators use these measurements to calculate body fat percentage. Moreover, because muscle tissue is denser than fat tissue, if your underwater weight is heavy, this indicates a lower body fat percentage.
According to research, underwater weighing is one of, if not the most valid technique for assessment of body fat and lean tissue in a clinical setting—aside from post-mortem analysis . But it does have a few downsides. For example, underwater weighing is uncomfortable, not convenient, and does not measure two key metrics: fat distribution and bone density.
How it works: the participant enters an enclosed pod where body volume is measured via air displacement plethysmography. This accurately calculates body density.
The Bod Pod has become more popular in recent years, but the results are not as extensive or impressive compared to other methods, such as underwater weighing and Dexa Scans .
How it works: small electrical currents are sent through the body to measure body composition. All bodily tissues, including muscle and fat, differ in electrical conductivity—this is because the water content varies.
BIA, known as bioimpedance analysis, is non-invasive, low cost, and is currently one of the more popular body composition analysis methods that you can do yourself at home . Although, it does have its limitations—more on these below.
We have a bonus method for you—one that you can do at home—but it does not provide the most accurate results. The measuring tape method is best paired with another measurement for increased reliability.
That’s right: you can use a tape measure and a handy equation to calculate an estimated body fat percentage.
How it works: take measurements around your hips, waist, and neck. An equation is used to estimate total body volume and subsequent body fat percentage.
How it works: Spren uses your smartphone camera, machine learning algorithms, and computer vision to provide you with accurate and reliable body composition analysis results.
It’s as simple as snapping a pic, waiting for your results, and tracking your progress.
Spren automatically generates numerous key biomarkers to help you monitor your health, going beyond the scale and showing you an accurate body composition analysis.
Now that you know what body composition is and how to measure it, you might be wondering: why does it actually matter?
Routinely measuring your body composition enables you to monitor your health and accurately progress toward your deeper health goals. For example, you can track marginal changes in fat and lean mass that would be very difficult to notice visually.
This data allows you to remain confident that you’re making progress, making it that much easier to stick to your nutrition and exercise plan.
Similarly, a body composition analysis tool that reveals fat distribution allows you to check risk factors for certain diseases and health conditions. For example, people with a higher android fat percentage—fat found in the abdomen, chest, and back of the neck—are more at risk of severe acute pancreatitis .
Fat distribution analysis enables you to take action to avoid various health conditions related to weight distribution, including stroke, type 2 diabetes, high blood pressure, hypertriglyceridemia, and impaired glucose tolerance.
So, the big question: how do you improve your body composition?
The best way to improve your body composition is to measure your body composition regularly using an accurate and repeatable method, such as Spren.
Doing so allows you to see changes in your body, including muscle and fat distribution. You can then adopt or change lifestyle and health habits in pursuit of your long-term goals, whether that means losing weight to reduce your risk of type 2 diabetes, or simply gaining muscle mass and limiting fat gain.
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