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Advanced BIA technology refined through years of innovation. Learn more about what makes InBody different.

What makes InBody technology different?

Traditional BIA technology measures the human body as a single-cylinder using one frequency, which increases the likelihood of inaccurate results.

Conventional BIA devices use empirical estimations based on factors like age and sex to help improve accuracy. While this may work for people with a standard body type, it is inaccurate for those who do not fit this mold, such as fit elderly adults.

Everyone has a unique body composition—that’s why InBody makes innovative technology tailored to the individual, not a group.

InBody’s medical-grade body composition analyzers use four pillars of technology to provide accurate, precise direct segmental measurement multi-frequency bioelectrical impedance analysis (DSM-MFBIA) extensively validated to gold-standard methods.

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The History of BIA Technology

1969 – Hoffner et al. and the Impedance Index

In 1969, Hoffer et al. conducted a series of experiments to prove that total body water and bioelectrical impedance were highly correlated, suggesting that impedance measurements could be used for determining total body water.

The impedance of the right half of the body was measured and yielded promising results—the squared value of this length measurement divided by impedance highly correlated with total body water (r = 0.92). The equation Hoffer et al. showed to correlate with body water is the impedance index (Height2 / Impedance) still used in BIA today.

1979 - RJL Systems and the First Impedance Meter

In 1979, RJL Systems made the first commercialized impedance meter that helped popularize the BIA method. The device measured impedance using a 50kHz current applied to the right half of the subject's body via electrodes attached to the back of the right hand and on top of the right foot.

Previous body composition methods like calipers or underwater weighing were uncomfortable, required skilled technicians to install or operate, and could not test a wide variety of populations. Alternatively, BIA was easy, fast, less expensive, and non-invasive, making it popular with many researchers, nutritionists, and medical experts.

1980s – Development of Empirical Equations

In the 1980s, studies proved BIA had high correlations with gold standard methods, such as underwater weighing and DEXA; however, some technical limitations began to surface.
Two limitations of BIA were its assumption of the human body as a single-cylinder and its use of a single frequency (50 kHz). This method worked for users with standard body types, but it was inaccurate for populations outside of this mold, such as fit elderly adults.

To improve accuracy, researchers derived various population-specific equations based on empirical data like age, sex, and body type for determining body composition.
While empirical estimations may accurately estimate a healthy individual’s body composition, they deliver inaccurate results and oversimplify health risks in population outliers like obese young individuals.

Late 1980s – Consumer BIA Device

In the late 80s, Japanese manufacturers released several BIA devices for personal use, which gradually became more popular than professional medical models due to technological constraints mentioned earlier.

Some of these BIA devices were scales that measured the impedance between the user's feet, while other models were handheld and measured the impedance between the user's hands.

Both types of models potentially produced inaccurate results because they measured the arms or legs directly and estimated everything else.

1992 – Kushner and the Proposal of Multi-Frequencies With Segmental Analysis

In 1992, Dr. Robert Kushner proposed that the technical limitations of BIA could be improved by measuring the human body as five separate cylinders instead of one. Each cylinder has a different length and cross-sectional area resulting in varying impedance values.

With the single-cylinder model, the thinness and smaller cross-sectional area of the limbs reduce their impact on whole-body impedance. However, since the torso makes up 50% of fat-free mass, it is crucial to measure the torso separately for accurate results.
Kushner also believed it was necessary to measure the body cylinders at different frequencies to distinguish intracellular, extracellular, and total body water. This distinction would allow a better understanding of fluid distribution, providing an accurate measure of the hydrated state of fat-free mass.

1996 – Dr. Cha Creates the InBody Professional Body Composition Analyzer

In 1996, Dr. Kichul Cha developed the world’s first 8-point tactile electrode system with direct segmental analysis to measure impedance in the five body cylinders using multiple frequencies (DSM-MFBIA technology).
Many BIA products provide segmental muscle and fat mass measures but not impedance, particularly in the torso.

The InBody device measured impedance in the limbs and torso separately, yielding highly accurate results without using empirical data based on age, sex, ethnicity, athleticism, and body shape. This innovative DSM-MFBIA technology makes the InBody a highly accurate and precise tool ideal for medical, fitness, and clinical applications.
Learn more about how our DSM-MFBIA technology sets us apart from other BIA devices.

MULTIPLE FREQUENCIES

8-POINT TACTILE ELECTRODE SYSTEM

DIRECT SEGMENTAL MEASUREMENTS

NO EMPIRICAL ESTIMATIONS

What is Bioelectrical Impedance Analysis (BIA)?

Bioelectrical impedance analysis (BIA) is a method for measuring body composition, including muscle mass, body fat, and total body water. Alternating low and high-frequency electrical currents are sent through the water in the body via contact with electrodes to measure impedance.

The impedance is used to determine total body water (TBW), which can then be used to derive your fat-free mass—the portion of your body that does not contain fat, including your muscle and bone—and finally, body fat.

Multiple Frequencies

InBody uses multiple currents at varying frequencies to provide precise body water analysis.

8-Point Tactile Electrode System

When measuring impedance with electrodes, contact resistance occurs. InBody accounts for contact resistance with strategically placed electrodes to ensure that measurements are accurate and reproducible.

Direct Segmental Measurements

InBody measures each of the body’s five cylinders (left arm, right arm, torso, left leg, and right leg) to deliver accurate and detailed results.

No Empirical Estimations

InBody measures your impedance independently, so your results are not affected by your age, sex, ethnicity, athleticism, or body shape.

Multiple Frequencies

Other BIA Devices

The ability to distinguish between extracellular and total body water is critical to identify fluid imbalances related to acute inflammation or edema. Many BIA devices use only one frequency at 50 kHz to measure impedance, which does not fully pass through the body’s cells and makes the accurate measurement of total body water impossible. As a result, patients with increased extracellular water may have overlooked health risks.

InBody Devices

InBody uses a combination of low and high frequencies to accurately determine extracellular, intracellular, and total body water. The use of multiple frequencies allows InBody devices to achieve a high level of precision. Medical practitioners can use InBody for measurements of body composition and fluid status.

8-Point Tactile Electrode System

Other BIA Devices

Many BIA devices lack a thumb electrode or have hand electrodes positioned close together. These designs can cause measurements to start in the palm, which has a high impedance and can cause inaccuracies or lead to inconsistent measurement starting points, reducing the reliability of results.

InBody Devices

The anatomical design of the InBody hand electrode creates a simple holding position that is easy to reproduce. When an examinee grasps the handle, current flows from the palm electrode, and the electrical energy, or voltage, is initiated at the thumb electrode. The point of measurement remains consistent for highly reproducible results.

Direct Segmental Multi-Frequency Bioelectrical Impedance Analysis (DSM-MFBIA)

Other BIA Devices

Traditional BIA views the human body as one cylinder. However, the short length and large cross-sectional area of the torso mean that even a minor measurement mistake can lead to substantial error. For the most accurate results, BIA devices should measure the torso separately.

InBody Devices

Direct segmental measurement bioelectrical impedance analysis regards the human body as five cylinders: left arm, right arm, torso, left leg, and right leg. InBody independently measures each cylinder to provide accurate measurements for the entire body.

No Empirical Estimations

Other BIA Devices

Many BIA devices use empirical equations to compensate for technological flaws, including the lack of torso impedance (due to whole-body impedance measurement), single frequency measurements (which are unable to differentiate between water compartments), and lack of reproducibility (from electrode placement or positioning). These empirical equations utilize data, such as age, sex, and ethnicity, to calculate body composition based on common trends rather than relying solely on the individual’s actual body composition.

InBody Devices

InBody measures body composition without relying on empirical assumptions based on age, sex, ethnicity, or body shape, producing accurate and precise results validated to gold standard methods. Simply put, InBody provides individualized feedback for progress tracking to help you achieve your goals.

Technology You Can Trust

Our advanced BIA technology has been validated in over 4,900 clinical studies worldwide and proven amongst the most accurate. Compared to DEXA, InBody has a high correlation to the Gold Standard method for Fat-Free Mass and Body Fat Percentage in an ambulatory population.

“Given the high level of agreement to DXA across BMI categories in estimating FFM and fat mass, S-MFBIA allows providers to further risk stratify patients and develop treatment plans.”

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InBody devices are used by leading professionals around the world to give their clients results they can trust and track.

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