The Use Of Bioelectrical Impedance Analysis (BIA)

The Use Of Bioelectrical Impedance Analysis (BIA)

Bioelectrical impedance analysis (BIA) is a tool for obtaining body composition that is based on the rate at which an electrical current passes through the body. Body fat (adipose tissue) generates more resistance (impedance) than fat-free bulk, slowing the pace at which the current flows.

 Medically reviewed by Dr K on 24th May 2022.

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  1. BIA Definition
  2. Is BIA Secure?
  3. Accuracy
  4. Should You Purchase One?

The Use Of Bioelectrical Impedance Analysis (BIA)

Bioelectrical impedance analysis (BIA) is a tool for obtaining body composition that is based on the rate at which an electrical current passes through the body. Body fat (adipose tissue) generates more resistance (impedance) than fat-free bulk, slowing the pace at which the current flows. BIA scales use bioelectrical impedance analysis to calculate body fat percentage.

You’ve definitely seen bioelectrical impedance analysis body fat scales on retail shelves or online. Because scales can be costly, you’ve undoubtedly questioned what bioelectrical impedance analysis is and if it’s worth paying for. 

Source - Greatist

BIA Definition

While the phrase “bioelectrical impedance analysis" may seem sophisticated, BIA devices employ simple technology. The pace at which a painless low-level electrical current flows through your body is measured by BIA.

A computation is utilised to estimate fat-free mass based on that rate. The device then utilises additional information, such as your height, gender, and weight measurements, to calculate your body fat percentage.

BIA Device Options

BIA devices come in a number of different forms, but each one needs two points of contact. The two points on a portable device are your two hands (called hand-hand BIA). The two points of contact on a standard BIA scale are your two feet (called foot-foot bioelectrical impedance analysis). When you use the device, you put each foot on a pad, and the current flows through your body between your feet. Hand-to-foot BIA devices can also be found.

BIA scales (also known as bioimpedance scales) are manufactured by a range of companies, including Omron, Tanita, Fitbit, Polar, and Homedics.

Many of the latest BIA scale models connect to a smartphone app, allowing you to monitor your progress over time.

The cost of your BIA scale will be determined by the product’s intricacy. Some scales get a result by using more than one frequency and more sophisticated algorithms. Some also provide segmental fat analysis, which means you can obtain body fat measures for each leg, arm, and belly.

Some argue that segmental fat analysis (using hand-foot BIA) is more accurate since hand-hand devices assess the upper body, the foot-foot scales evaluate the lower body.

Is BIA secure?

Most individuals regard bioelectrical impedance analysis equipment to be safe. However, anybody who has an electronic medical device, such as a cardiac pacemaker or an implanted cardioverter-defibrillator, should not utilise BIA (ICD). Furthermore, most device manufacturers advise pregnant women not to use their equipment.


According to certain studies released in 2015, bioelectrical impedance analysis is a reasonably reliable tool for assessing body fat. However, most research studies do not put the scales on the market to the test. And experts largely agree that the accuracy of the measurement is affected by the device’s quality.

There are several other factors that might modify a reading when using a BIA scale.

  • Bodyweight. Obese adults may have less accurate bioelectrical impedance analysis.
  • Hydration level.  Dehydration may result in an underestimation of fat-free mass (muscle and bone).
  • Recent strenuous exercise. High-intensity exercise may impair BIA reading accuracy.
  • A load of training.  Some scales offer a setting for athletes who work out often. The settings are designed to improve accuracy.
  • Consumption of recent food or drink. According to the findings of a 2015 research, BIA is more accurate following an overnight fast.

According to several studies in 2008, ethnicity and external conditions (such as skin temperature) may also alter the accuracy of BIA assessments.

Should You Purchase One?

Even if you acquire an accurate reading on a bioimpedance scale, the result is just an estimate of your total body fat percentage. Bioelectrical impedance analysis does not offer a precise assessment of total body fat. Most scales can’t even tell you where your fat is on your body.

So, is it worthwhile to invest in a bioelectrical impedance scale? It might be for a lot of individuals.

Despite the fact that numerous aspects might influence the accuracy of your reading, a BIA scale used on a regular basis can show you changes in your body fat over time. Although the actual figure is not precise, you may still monitor changes in your body composition through food or exercise.

Furthermore, if you use a fitness tracker from a company like Fitbit, you can purchase a scale to link with the device and monitor all of your body data in one place. The Fitbit Aria 2 wi-fi smart scale calculates weight, body fat, and BMI. The data is effortlessly synced with the Fitbit dashboard, allowing you to monitor how the statistics vary over time in conjunction with daily activity and dietary changes.

Body fat scales that employ bioelectrical impedance analysis are a beneficial investment for many customers since they provide various functions at a reasonable price and because it is a fast and simple approach to determine body fat percentage.


  2. Gagnon C, Ménard J, Bourbonnais A, et al. Comparison of Foot-to-Foot and Hand-to-Foot Bioelectrical Impedance Methods in a Population with a Wide Range of Body Mass Indices. Metab Syndr Relat Disord. 2010;8(5):437-441. doi:10.1089/met.2010.0013
  3. Demura S, Sato S. Comparisons of accuracy of estimating percent body fat by four bioelectrical impedance devices with different frequency and induction system of electrical current. J Sports Med Phys Fitness. 2015;55(1-2):68-75.
  4. Dehghan M, Merchant AT. Is bioelectrical impedance accurate for use in large epidemiological studies? Nutr J. 2008;7:26. doi:10.1186/1475-2891-7-26
  5. Androutsos O, Gerasimidis K, Karanikolou A, Reilly JJ, Edwards CA. Impact of eating and drinking on body composition measurements by bioelectrical impedance. J Hum Nutr Diet. 2015;28(2):165-171. doi:10.1111/jhn.12259

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