InBody & BIA – How Does it Work?

How it Works:


Bioelectrical Impedance Analysis

Bioelectrical Impedance Analysis (BIA) measures impedance by applying alternating low-level electrical currents through the water in the body.

InBody use this method to measure body composition, which divides your weight into different components, such as lean body mass and fat mass, to aid in assessing your health and help guide interventions.

Through the use of InBody’s unique and patented technologies, InBody has overcome the traditional limitations of BIA and produced a device that yields incredible precision used in medical, research, and fitness applications around the world.

How InBody Revolutionised BIA

How InBody Started

In 1996, Dr. Kichul Cha revolutionised the world of BIA by developing the InBody which overcame the traditional limitations of BIA. This was achieved by the use of an 8 point tactile electrode system with direct segmental analysis to measure the impedance of the 5 different body parts using multiple frequencies. By directly measuring the impedance in the limbs and the torso this produced highly precise results with out using emperical data based on factors such as age, gender, body type and ethnicity.

How InBody has revolutionised BIA technology by not using age and gender to make assumptions about a person’s body composition.

What are these assumptions?

Empirical data such as age, gender and body type are used by other devices to overcome poor accuracy and reproducibility in measuring a person’s body composition. These assumptions go unnoticed when scanning an ‘average’ person, but in the case of someone outside the norm, the results produced will show huge discrepancies. This method should not be relied on for a precise measurement.

What sets InBody apart from other BIA devices?

InBody is the only BIA device that does not use age and gender to make assumptions in your body composition measurement. The results are extremely precise, and as unique as the person standing on the device. You can change your age and/or gender on an InBody device and your measurement will not change because of it, as YOU have not changed.

This is one of the underpinning reasons why InBody is used around the world in extensive studies and utilised by top sports people, medical institutions and NASA. InBody is currently used in over 70 countries worldwide

Why we ask for age and gender?

We request age and gender simply as a way of providing relevant guidelines on your result sheet. These are generally found in brackets, next to your actual results. This allows you to compare your results against a broad-spectrum average. Change your age and gender on an InBody device, your measurements will not change because of that – only the guidelines will change.

Watch the video and see for yourself:

InBody’s patented 8-point thumb & palm technology

When measuring impedance through any type of electrode, contact resistance occurs. It is important to control the contact resistance, in order to correctly measure the resistance in the body.

The 8-point tactile method separates the current and voltage starting point. This measurement always begins at a fixed point in the wrists and ankles. This is advantageous, as the contact resistance from the skin has been removed. This creates the high precision of reproducing the results that InBody are renowned for.

Multiple frequencies used in measurements

By using several different frequencies, more resistance values are attained, providing more information for the InBody scan. The InBody 770 utilised 6 different frequencies that measure each segment, providing a total of 30 separate impedance values.

Electrical current has a different penetration force depending on frequency. Low frequencies measure the water outside the cell (extracelluar water), as they are unable to penetrate the cell wall.  Higher frequency will measure the water content inside of the cell (intracellular water) because it penetrates the cell wall.

By using a diverse set of frequencies, the InBody can measure water contents inside and outside the cell separately. Controlling the path of high frequency waves is very difficult. This technical know-how is an InBody specific specialty and has been accumulated over many years of experience in the field.

Measuring your body parts individually

The technical term for this is Direct Segmental Multi-frequency Bioelectrical Impedance Analysis (DSM-BIA). It separately measures the impedance (resistance to alternating electric currents) of the trunk, arms, and legs of our body.

This new measurement concept measures the resistance of the cross point of two flows and takes the resistance values of the arms, legs and the body trunk.

Why is this important? The human body is composed of five cylinders: the arms, legs and trunk. With the technology of the InBody, the trunk is directly measured. The trunk is occupied by various internal organs and its metabolic characteristics are different from the other parts of the body. Although difficult, it is important to precisely and directly measure the trunk, since the trunk has very low resistance compared to the arms and legs.

Example Result Sheet from InBody 770

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