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How Do Scales Measure Body Fat (And Are They Accurate)?

Fitness weight scale

Scales are a popular way to track weight loss and monitor health. However, it’s beneficial if you gather additional data to accurately assess your health and wellness, such as your body fat percentage. In fact, body fat percentage can be one of the most telling metrics for estimating physical condition and predicting long-term health issues.

Body fat plays an important role in cushioning organs as well as regulating hormones and other chemicals in the body. Healthy levels for women range from 14% to 38% and the range for men is 6% to 24%, but zero body fat should never be the goal.See Disclosure 1

At the same time, there are risks associated with too much body fat, including high blood pressure, diabetes, stroke and certain cancers. This is why staying within the healthy window is a worthy goal for your long-term health. Fortunately, you can now find scales that will not only give you a reading of your body weight but also your body fat percentage.

How do scales measure body fat?

Digital weight scales that use bioelectrical impedance analysis (BIA) can estimate your body’s composition. BIA works by sending a small and painless electrical signal through your body. The signal passes more easily through water and lean tissue, like muscle, than it does through fat. So, by measuring how long it takes for the current to pass through your body, the scale can estimate your body fat percentage.

What factors can affect the accuracy of a scale reading?

Factors such as dehydration or overhydration can influence readings, as can calluses on the feet and certain health conditions. But even more significantly, scale design and individual physical factors can cause inaccurate readings. Even though most body composition scales feature the option to create personal profiles with data that includes height, most do not factor in differences in limb length or weight distribution, which can vary widely across people of the same height.

Most body fat scales will measure the journey of the electrical signal up one leg, across your pelvis and down the other leg by using an electrode beneath each foot. This design can pose two problems for accuracy. First, having longer legs will increase the time it takes for the signal to travel, meaning you may get an overestimate of your body fat percentage if you have long legs relative to your height (with the reverse being true for short legs).

Secondly, if you have a significant difference in body fat percent above and below your pelvis, the foot-to-foot style scale will not account for this since it does not include information from your belly and upper body in its reading. To counteract these accuracy issues, some scales use a hand-to-foot reading by including electrodes you hold as well as electrodes under each foot on the scale. This design allows the signal to travel through more of your body before taking a reading.

However, there’s still room for improvement in these personal care devices. Neither foot-to-foot nor hand-to-foot designs let you know where in your body your fat percentage is highest, which is useful information. Excess fat between your organs can pose more health risks than fat stored in the thighs.

How can I get the most accurate reading?

Keep in mind that no reading from an at-home device will be completely accurate, but there are ways you can decrease the margin of error.

Generally, the more information your device allows you to enter about your personal measurements and characteristics, the more accurate your readings will be. There are also smart scales that connect to apps within fitness trackers and smartwatches to gather pertinent information. Plus, if you have significant differences in weight above and below your pelvis, including more electrodes will also provide more accuracy.

To help achieve truer results, some body fat percentage measuring devices now include even more electrodes beyond just the hands and feet to help increase overall accuracy and deliver readings that identify exactly where body fat is located. For instance, you can choose to schedule a dual-energy x-ray absorptiometry (DEXA) scan at a medical facility that utilizes this advanced technology.

Beyond the scale.

While knowing your weight and body fat percentage are important, they are not the only indicators of your health and wellness. Being active on a regular basis, eating a balanced diet and getting the daily recommended amount of vitamins will help you feel your best, which is a great sign in itself. Keeping up with sleep solutions should also be prioritized because you tend to perform better and make healthier choices when you are well-rested. As the latest healthcare technologies continue to emerge, you can take a more proactive role in managing your health.

Additional information: These statements and any information contained herein are intended for educational purposes only and are not meant to substitute for medical care or to prescribe treatment for any specific health condition. Carefully review product labels for instructions and important safety information and consider consulting with a health care professional regarding your use of health and wellness products.

References.

1. Myers, Wyatt. “Why Your Body Fat Percentage Matters.” UHealth, University of Miami Health System. February 24, 2020. https://news.umiamihealth.org/en/why-your-body-fat-percentage-matters/. 

Additional information:

These statements and any information contained herein are intended for educational purposes only and are not meant to substitute for medical care or to prescribe treatment for any specific health condition. Carefully review product labels for instructions and important safety information and consider consulting with a health care professional regarding your use of health and wellness products.