How Accurate are Body Fat Scales?

Cindy Wilson Thumbby Cindy Wilson
BS, Dietetics and Nutrition

Weighing scales like these Healthcare Scales give you a measure of your body weight. But measuring bodyweight doesn’t give the whole picture of our health. Our body weight is composed of fat, muscle, bone, and water. To get a clear picture of our health, we need to have more detailed data about our weight, and Body fat scales does just that. Body fat scales provide the percentage of fat, muscle, and water in our body along with our weight.

When you have all this information, you can reduce weight and stay fit in a much healthy way. It is true because exercising regularly can increase the good muscle and reduce unwanted fat to keep your weight unchanged. In a best weighing scale, you won’t get the information about the change in muscle and fat, so it is essential to get a detailed overview of your weight when you are trying to lose weight. Even if you are not trying to lose weight, fat scales help you to figure out whether you have a good fat-to-muscle ratio.

Body Fat Scale 1

It’s fascinating to see a device that gives your fat, and muscle composition by just stepping on it. But how do they work?

Working of Body Fat scales.

Most of the body fat scales available in the market use the concept of bioelectrical impedance. Bioelectrical Impedance Analysis (BIA) is used to estimate the percentage of fat, muscles, and other substances in your body. There are sensors present underneath the body fat scales that work on the BIA when you step on it. The sensors detect when you step on the scale and send out weak electrical signals through your legs. They only send out a small amount of electrical current, so you don’t have to worry about any damage to your body. These current signals pass through your legs and across your pelvis region to reach the sensors again. When the signals are passing through your legs, they will get resistance from your body fat, muscles, and other tissue substances. The senors finds out this electrical resistance and then uses a mathematical formula on the electrical resistance value to find out your body fat composition along with other information.

The scale also needs your age, height, and gender information to find your body weight composition. You will probably provide this information using a smart app that supports the respective fat scale. After the calculation, you can get the information about your fat, muscle mass, water composition, bone density, and weight on the app or on the weighing scale.

While it is marveling to see a device churn out all these different compositions in our body without much work, it is important to understand the accuracy of these body fat scales.

Body Fat Scale 2

Do the body fat scales really work? If so, How accurate they are?

While they are considered safe to use, most researchers agree that they only give a rough estimate. They are also not accurate enough to track the fat composition over time as you exercise regularly. There are various reasons that contribute to this rough estimate of the body fat scales. But the main problem with the foot-to-foot body fat scale is that they only measure part of your body fat composition. The electrical signals only pass through your legs and the pelvic region. With this type of fat scale, you’re only measuring the weight composition on your legs and approximating the total value. You will not get an accurate composition of the total body fat with this type of fat scale.

The other factor that affects body composition is the hydration level in your body. Water mass also affects the resistance level of the electrical signals and the fat scale may interpret water mass as fat. The change in water mass influences the fat scale’s ability to calculate the fat mass accurately.

The body fat scale also seems to get affected by the type of exercise you do. If you do cardiovascular exercise a lot, you get to lose more of the water mass from an increase in plasma volume. This change in water mass affects the ability of the fat scale to accurately measure your fat composition.

The commercial fat scale also gets affected by many other variables like your gender, age, height, stature, where the fat is stored, when you ate last, and more. To sum it up, the fat scales are not accurate. They may give a rough estimate, but they are not consistent in providing it. This is proved by various research conducted around the world.

A 2016 study performed by the Gateshead Millennium Study Core team found that most of the body fat scales don’t use standard, published mathematical formulas for measuring weight composition. It led to inaccurate results of weight composition by the fat scales. When you buy cheap fat scales, they tend to use non-standardized formulas to measure the fat composition. So you will definitely get inaccurate results.

A 2016 consumer report study compared the results from different home body fat scales with a lab-based machine. They found the most accurate readings of the body fat scales were off by about 21 percent while the least accurate readings by the fat scales were off by 34 percent.

To sum up the question, a quality body fat scale does give a rough estimate of your fat composition. But it can be easily influenced by various factors such as your hydration level, exercises that you do, and many more.

Pros in using Body fat scale

While they are inaccurate, they do provide the comfort of measuring your fat composition from your home. You don’t have to go to a specialized lab or gym to measure your fat composition.

Cons in using Body fat scale

As clearly explained, the body fat scale is not accurate or consistent enough to trust the results. With a low-reliability rate, it is better to not measure your fat composition than to measure with inaccurate results.


Body fat scales use some innovative techniques to measure body fat composition even though they are not accurate. They are safe to use but the accuracy is not good enough to recommend body fat scales. We hope that you got some information about the working and accuracy of the body fat scales.

About Author

Cindy Wilson Thumb
BS, Nutrition & Food Science | Connect with on LinkedIn
Cindy Wilson

Hello, I am Cindy, and this a website where I inspect everything related to nutrition and a healthy lifestyle. I have a BS in Dietetics and Nutrition (Kansas State University) and have completed a dozen specialty courses related to nutrition, biochemistry, and food science. I am open to learning more, but foremost I would like to share all my knowledge with you.

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