Editor’s Note: This post was updated on December 16, 2024 for accuracy and comprehensiveness. It was originally published on June 14, 2017.

A few days ago, you stepped on the bathroom scale, and you’re stoked to see your weight is going down. People have even started complimenting you on how strong and lean you look!.

The effort you have put in the past six months, weekly meal plan and thrice-a-week HIIT sessions, have finally paid off!

But this week, you step on the scale again and the numbers are higher than the last time. You check your body mass index, and it’s gone up! Plus, you have a bloated belly to boot! You freak out and wonder what’s going on.

Sounds familiar?

Whether you’re a professional athlete training for next season or a self-proclaimed newbie who simply wants to get fit and healthy, an in-depth body analysis of your body composition is crucial in helping you track progress and maintain your goals.

Sure, nothing beats working with health and fitness pros regularly to help reach your body composition goals. Yet taking a body analysis and understanding the different variables that make up your body composition has its advantages too.

First, it can help you become more objective (no need to freak out when your weight fluctuates!) in maintaining body composition success because you know exactly where you are from a broader perspective. In a nutshell, you get to see the bigger picture through intimate knowledge of the parts that make up body composition.  Second, you’ll gain a more detailed, accurate view and be able to compare what’s working to what’s not. As a result, you’ll know exactly what specific steps or adjustments you can take towards your goal, whether that is to gain more muscle mass, lose fat mass or both.

In this article, we’ll take a closer look at one of the most valuable outputs in the InBody result sheet — Segmental Analysis.

What is Segmental Analysis?

Body composition analysis is a method of describing what your body is made of, including fat, muscle, protein, minerals, and body water. In conventional BIA body composition analyzers, the entire body is analyzed as just one section or cylinder. This single-cylinder method results in only one impedance value, which is used to determine the body composition data for a user.

However, because each body part has different volumes, the single-cylinder method results in very skewed data. Segmental Analysis provides body composition data in segments in addition to the usual full body analysis.

For example, the InBody technology divides the body into five segments or “cylinders”:  the two arms, two legs, and the trunk (the area between the neck and legs.)

Anyone can theoretically be underdeveloped/overdeveloped (depending on your body goals) for certain body segments.  The good news is that segmental analysis allows you to identify and compare these segments.

Shown: Body Composition Result Sheet from the InBody 770

In the InBody result sheet, the top bar shows Lean Body Mass (in pounds) is in a given segment. The top bar of the Segmental Lean Analysis compares the pounds of Lean Body Mass in proportion to your height and gender. This top bar can also be used for comparison between segments. An uneven weight distribution between the right and left legs may be a sign of overtraining or injury. Later on, you will see how strength and conditioning coaches use segmental analysis to train their athletes.

The number shown at the bottom bar is the percentage relating the lean mass in the segment that is analyzed to the overall body weight. This shows whether the amount of Lean Body Mass you have in a segment in proportion to your total body weight is sufficient. The 100% = sufficient.

It’s worth noting that the Lean Body Mass being referred to in the results sheet doesn’t refer to how much “muscle” (also known as Skeletal Muscle Mass) you have in each segment. So it would be wrong to call Segmental Lean Analysis a muscle analysis chart. While it’s a given that skeletal gains in a body segment will be reflected as gains in the Segmental Lean Analysis chart, not every gain in Lean Body Mass can be explained by muscle gain. How come?  Because Lean Body Mass also accounts for body water. This makes Segmental Analysis useful not just for tracking muscle, but also for certain injury and disease states (which will be discussed in detail below).

You can learn more about the distinction in Lean Body Mass vs. Skeletal Muscle Mass: What’s the Difference?

In hindsight, your segmental distribution could indicate that you have maintained, developed, or lost muscle/fat mass proportionately. While it’s true that you can’t spot-reduce fat, you can develop or maintain certain muscles in the body by using them more, whether through exercise or your day-to-day activities.

How Segmental Analysis Works: Understanding the Technology

Shown: InBody 770

In order to understand how segmental analysis is measured, let’s go back to the basics of body composition testing first.

There are several ways to track and monitor body composition. Some are quick to perform, others require a lot of effort. Results can vary too, ranging from the most basic to the most complex. Currently, the following methods are most frequently used in body composition testing:

• Skinfold Calipers

• Hydrostatic Weighing

• Dual Energy X-ray Absorptiometry (DEXA)

• Bioelectric Impedance Analysis (BIA)

You can learn more about the aforementioned methods in Body Composition 101: The Beginner’s Guide

Segmental analysis falls under the DEXA and BIA method.

BIA devices range widely in quality, technique, and accuracy. Keep in mind that not all BIA devices will measure impedance in the entire body.  For instance, there are handheld devices that only measure arm impedance and estimate results for the lower body. Meanwhile, there are home bathroom scales that use BIA to directly measure impedance in the lower body but can only make estimates for the upper body.

Modern, medical-grade BIA devices that perform segmental analysis view the human body as five “cylinders” or segments. Accurate and independent measurements of each cylinder are essential for providing analysis not just for each cylinder, but for the entire body.

Direct Segmental Multi-frequency Bioelectrical Impedance Analysis (DSM-BIA)

InBody’s signature technology is Direct Segmental Multi-frequency Bioelectrical Impedance Analysis (DSM-BIA) which separately measures the impedance of the arms, legs, and trunk.

Although accurate impedance measurement of each cylinder is critical for reliable results, the most important measurement is trunk impedance. Why the trunk?

The trunk contains essential internal organs, and their metabolic characteristics are different from the other parts of the body. In terms of impedance, it is important to precisely and directly measure the trunk because resistance values in the trunk are much lower than those in the arms and legs. This means that the margin of error for trunk measurements must be controlled as much as possible. DSM-BIA helps reduce this margin of error, giving users accurate and not estimated rest results.

How Accurate Is It?

If you’re curious about the accuracy of DSM-BIA in contrast to DEXA (considered as the gold standard in body composition analysis), a Dutch study on middle-aged adults found out the answer for you.

The researchers examined the accuracy of (DSM-BIA) in assessing different body composition parameters among their subjects while using DEXA as a reference standard. And their conclusion?

DSM-BIA is a valid tool for the assessments of total body and segmental body composition in the general middle-aged population, particularly for the quantification of body lean mass.

And while we’re still comparing DSM-BIA and DEXA, it’s also worth noting that DSM-BIA has been shown to be a rapid noninvasive alternative to DEXA in assessing segmental lean soft tissue (LST)  among female athletes.

Another study on obese children revealed that segmental analysis can help determine the right exercise patterns for weight loss and prevention of associated diseases including obesity, type 2 diabetes, and cardiovascular diseases.

Finally, a 2014 review of literature on the role of BIA in clinical status monitoring and diagnosis of diseases stated that segmental BIA is more precise than the ankle-foot method in detecting fluctuation of ECF (extracellular fluids) due to differences in posture. Plus, it provides a better estimation of TBW (total body water) than total body measurements when compared to reference methods.

You can learn more about body water in the context of body composition in Your Body and You: A Guide to Body Water

Who Will Benefit the Most from Segmental Body Analysis?

Segmental body analysis is particularly useful for anyone who wants to measure and track their body composition progress. However, it can prove extremely beneficial for the following groups:

1. Anyone who is trying to build or rehabilitate a particular body part such as athletes and patients with certain disease conditions.

Did you know that the University of Northern Colorado Cancer Rehabilitation Institute (UNNCRI) experienced a massive boost in their patients’ rehabilitation session and retention rates after using DSM-BIA?

By using InBody’s Segmental Lean Analysis and other body composition outputs, the specialists at UNCCRI were able to prescribe more detailed therapies and more precise exercise interventions for patients. As of last month (May 2016), UNCCRI posted an 87% attendance rate – the highest rate in the institute’s 20-year history.

Another noteworthy case study on the benefit of segmental analysis in terms of rehabilitation is Restoration Healthcare’s data-driven approach in helping athletes recover from repetitive trauma issues. The functional medicine practice in Southern California relies on segmental analysis to uncover certain clues, trace the “why” behind the readings, and implement a customized program for their patients.

2. Athletes who want to assess the specific impact of their training regimens.

For instance, the Cirque du Soleil team depends on Segmental Analysis in identifying asymmetries among members, and designing programs to help address these imbalances. DSM-BIA has also helped injured performers quickly recover and get their body back by monitoring specific changes during the reintegration cycle.

3. Sedentary adults who want to monitor and track their diet/exercise efforts.

Upper or lower body imbalances are fairly common in today’s increasingly sedentary workforce, and you’ll likely encounter cases where the upper body is developed, but the lower body is severely neglected.

This unbalanced weight distribution can increase the risk of injury and affect mobility in the future.

4. “Skinny Fat” individuals who want to improve their body composition.

Also known as sarcopenic obese, skinny fat folks have more fat mass than is healthy for their bodies and have low amounts of Lean Muscle Mass. Their relatively overdeveloped fat or underdeveloped muscle mass contributes to their body weight.

Below is an example of a segmental analysis reading of a skinny fat individual:

Shown: Body Composition Result Sheet from the InBody 570

For this person, who is a 5’4” female, 135 pounds is just above her ideal weight, but within what is considered normal (BMI 22.5).  However, it’s clear to see that this person does not have enough Skeletal Muscle Mass and has excessive body fat. If you do the math, this person has a body fat percentage of 35.0%.  This surpasses all upper limits of percent body fat ranges, which are usually around 28%. 

5. Assess Risk for Elderly Individuals

The elderly are at particular risk for not having sufficiently developed Lean Body Mass due to their tendency to lose muscle as a result of reduced physical activity. This affects their ability to complete daily tasks and increases their risk for falls and injuries.

 6. Patients with chronic issues.

Segmental analysis also provides invaluable information that healthcare professionals can use to help patients with chronic medical conditions. In fact, segmental body composition evaluation has been shown to be valuable in the early detection of muscular impairment in patients with COPD (Chronic Obstructive Pulmonary Disease).

By the same token, segmental bioimpedance analysis provides a more accurate data on extracellular volume taken from each segment among end-stage renal patients treated by hemodialysis.

Shown: Body Water Result Sheet from the InBody S10 

Putting It All Together

When done properly, Segmental Lean Analysis is one of the most powerful outputs in body composition results. Think of it as a magnifying glass to see if each corresponding segment is in proportion. The analysis makes it easy to uncover problem areas and identify imbalances accurately.

Now that you know how advanced body composition technology can help you stay healthy and feel your best, go get your body composition analysis tested to see what you find out. Just make sure it’s one with Segmental Lean Analysis, so you can see your lean body mass.

***

Kyjean Tomboc is a nurse turned freelance healthcare copywriter and UX researcher.  After experimenting with going paleo and vegetarian, she realized that it all boils down to eating real food. 

People are finally taking notice: body composition is useful for measuring health; BMI is not.  Even the New York Times is publishing stories about the pitfalls and inaccurate uses of BMI.  The jury is in: if you want to be on the cutting edge of health and fitness, you need to be involved with body composition analysis. To do that, you need a device that measures body composition, and some of the most popular body composition tools are devices that use bioelectrical impedance analysis (BIA).

BIA devices are becoming one of the most popular and convenient ways to measure body fat percentage and body composition because of their speed, convenience, and accuracy. There is no shortage of them to buy, and costs range greatly.  Some are under $50, while others range in the tens of thousands.

Why?  What’s the difference between them?

Fundamentally, all BIA devices operate using the same method: a small, safe, electric current is sent through a person’s body.  Along the way, it encounters resistance due to the variation in water content in different parts of your body – like in fat and muscle – and that resistance is measured.  This information is then analyzed and translated into useful outputs, such as body fat percentage and lean body mass.

So if every device uses the same method, why the range in price? What are some things to consider when looking for a BIA device, especially those that influence the cost? Here, we’ll break down the most important things to look into when buying a BIA device to measure body composition.

Check the frequencies

All BIA devices use at least one electric current set at a specific frequency to measure body composition.  In the past, this frequency was traditionally set at 50 kHz.  Some devices today continue to use this single frequency.

However, beginning the early 1990s, research began to accumulate suggesting that single frequency devices set at 50 kHz did not accurately predict changes in total body water, and that the use of multiple frequencies – multiple currents set at a different frequencies – was a superior method in terms of accuracy.  So, the first thing you will want to check when looking at BIA devices whether it is a single or multifrequency device because generally speaking, devices that use multiple frequencies are found to be more accurate.

Why are multifrequency devices typically more accurate?  The answer lies with how BIA devices measure that resistance – more accurately termed “impedance” – when the current travels through the body.

As the current travels, the water in your body will naturally resist the flow of the current as it travels.  This is called resistance.  When the current encounters a cell, the cell wall will cause a “delay” as the current builds up enough energy to pass through the cell wall.  This brief “time delay” is referred to as reactance.  Impedance is a combination of these two values.

How does this apply to frequencies? Lower frequencies don’t have enough energy to pass through cell walls easily, so they often follow an easier path by traveling around cells. This means lower frequencies are better suited for measuring extracellular water.  Conversely, higher frequencies are better suited to penetrating cell walls and can measure both intracellular and extracellular water. The end result is that those frequencies can measure all of your body water and provide you with an accurate result for your lean body mass.

Ideally, you will want a device that uses at least two frequencies – one on the lower end and the other on the higher end. The more frequencies you have, the better the device is able to gather the information required to accurately measure your total body water, and from there, your body composition.

See what outputs it provides

BIA devices range widely in capabilities and the outputs they are able to produce.  Some devices only measure your body fat percentage, while others can give much more information.  Typically, the better quality the BIA device, the more comprehensive outputs you will receive.

Every BIA device on the market will at least give body fat percentage.  Using body fat percentage as an indicator of your overall health and weight is a very useful metric and a much better tool than simply monitoring your scale weight.

However, just as relying solely on scale weight isn’t advisable, neither is relying solely on body fat percentage.  This is because body fat percentages can fluctuate for many reasons, not all of these changes are related to weight gain or loss.

Here are a few other BIA outputs to look for and some reasons why you would want to track these in addition to body fat:

• Skeletal Muscle Mass: Skeletal Muscle Mass is the muscle that you can grow and develop through exercise and proper nutrition.  It also has a significant influence on change in Lean Body Mass.  However, Lean Body Mass can also be influenced by other factors such as body water. If you are tracking Skeletal Muscle Mass, you’ll be able to cross reference your muscle gains against your Lean Body Mass to ensure that those gains are due to muscle, not water.

• Body Water Analysis: Since BIA devices all measure total body water via impedance, if your device can give you this information, you’ll know how much total body water you have.  If your device can further break this down into intracellular and extracellular water components, you’ll be able to understand your body water levels are properly balanced.  With that information, you’ll know if you have any unusual swelling due to inflammation, injury, etc.

• Phase Angle: Phase Angle is a measurement of the relationship between reactance, resistance, and impedance.  It’s able to give you an idea of the integrity of your cell walls, which gives an indication of their ability to retain water.  This has an impact on your overall health.  By tracking Phase Angle, you’ll be able to get an idea about the health of your individual cells and how much water is inside them.

Find out what information it needs (important)

All BIA devices are going to require your weight at the very minimum.  For this reason, many BIA devices take the form of bathroom scales.  These devices measure your weight and calculate your body composition results using your weight at the time of testing.

However, not all BIA devices are scales.  BIA technology is being used in handheld devices for convenience, as well as devices that use adhesive electrodes and require a person to lie down while testing.  These types of devices will require a user to enter in their weight manually.  However, unless you weigh yourself right before testing, this information would have to be estimated based on your memory, which could cause inaccurate results.

Another fairly common user input requirement is age or gender.  However, these requirements aren’t to personalize your results; they’re to tell the device which equations to use to calculate your results.  In the BIA industry, these equations are known as empirically derived prediction variables – also sometimes referred to as “empirical estimations.”

For example, the average person tends to gain body fat mass as they age.  This trend has been observed over time, and equations have been developed to account for this fat gain.  By entering in your age, the BIA device will compare the raw data it gets from you and adjust it based on the data it has for your age.

BIA devices often use empirical estimations to improve the accuracy of their results.  They work on the basis of adjusting the raw results for an individual of your age and gender.  Age and gender are common to nearly all BIA devices.

Height is also a common requirement for many BIA devices. It’s an unbiased physical attribute, just like weight.  Unlike age and gender, however, height is necessary not because adjustments need to be made to results, but instead to give the BIA device a frame to understand the impedance results.

Impedance increases as height increases because the current has to physically travel further and will encounter more resistance.  However, high impedance is also associated with a greater proportion of fat mass to lean body mass.  With accurate height measurements, the BIA device will understand how to interpret the impedance values correctly, which is why nearly all BIA devices require height measurements.

Understand what’s measured and what’s not

The design of many BIA devices are such that impedance is measured for a certain section of the body, and the results of that section are used to estimate the remaining sections of the body.  Before choosing a BIA device, you should know what exactly your device is measuring and what it is estimating.

Home scales that use BIA technology to determine body composition operate by sending currents up one leg and down the other.  Impedance is only actually measured for the legs.  In order to calculate the upper body, the device will make assumptions about the composition of your body based on the composition of your legs (and if using age and gender data, adjusting for those as well).

Handheld BIA devices only measure impedance in the arms and upper body.  Similar to how the legs are measured, these types of BIA devices will estimate the lower half of the body with the results from the upper body.

Other devices that use the “Whole Body” impedance use a method that is somewhat misleading.  Unlike scales and handheld devices, the current does travel through the entire body in the sense that it travels from through both the upper and lower body.  However, “Whole Body” impedance devices do not actually directly measure the entire body.  Typically, “Whole Body” impedance devices get most of their measurement data from the arm and leg that the electrodes are placed on.  Just like handhelds and scales, these devices must estimate results for the rest of the body.

Finally, there are devices that use Direct Segmental Multifrequency-BIA technology (DSM-BIA).  These devices programmed in such a way that they analyze your body in five distinct sections – the two arms, the two legs, and the torso.

Each of these sections is analyzed independently, and from these, a measurement for the entire body is produced.  This is similar to how DEXA machines operate, and when compared against DEXA results, DSM-BIA technology was found to be accurate.  In comparison to other BIA methods, DSM-BIA offers results that are based on direct measurements, without using estimations to compensate for the areas that were not directly measured.

Summary

There are a lot of things to consider when looking for a BIA device.  When you’re assessing which device to go with, it will help you to remember the following:

• Accuracy generally will increase with multi-frequency devices.  You’ll want at least two frequencies for reliable measurements.

• You can do more with more results. Changes in body fat percentages can be tricky to explain if the only outputs you have are Fat and Fat Free Mass.

• Check what information the device needs from you in order to test.  If it requires your age and/or gender, it may be giving you estimations based on the results of the general population.

• Understand what the device is actually measuring and what it is estimating.  If accuracy is important to you, you’ll want as much of the body measured as possible.

In the world of body composition analysis, bioelectrical impedance analysis (BIA) is almost a dirty word.

Although well-known and popularly used in consumer home/fitness equipment, BIA technology has been disregarded for years when it comes to medical or professional purposes.  And for good reason: many early BIA devices had serious design flaws.  Even today, many people immediately dismiss BIA technology as technology that can only give ballpark estimations, even in the best of circumstances.

However, BIA has come a very long way over the past few decades.  So far, in fact, that some bioelectrical impedance devices are now producing results that nearly mirror results generated by DEXA, an industry-regarded gold standard.

Really? Yes, really.

Imagine if you could determine body composition with a device that used technology which had all the convenience of traditional BIA, but combined it with the precision and reproducibility of a gold standard procedure.  Imagine if that device was small enough to be placed anywhere: a doctor’s office, a gym, even a bedroom.  Imagine if that device could track your results forever and illustrate your progress over time.

Today, devices like these exist.

If you haven’t interacted with BIA technology recently, or the last time you encountered it was in a Fitness Science textbook in a college class years ago, consider this your crash course update on modern, 21st century, BIA technology.

Why BIA Gets a Bad Name

Many of the valid concerns people have about using BIA technology stem from outdated, older technology.  If you’re concerned about the accuracy of BIA devices, you probably have very legitimate reasons.  These devices fall into three general groups:

1. BIA Scales

2. Handheld BIA Devices

3. “Whole Body” Impedance Devices

Let’s look at each one to see what the concerns are and where they come from.

• BIA Scales

When people think about BIA devices that measure body fat, many of them think about something that looks similar to this:

This is a traditional digital scale that incorporates BIA technology to determine body fat percentage.  To use it, you must enter your age, height, and gender.  Some devices require body type, too. Then, you stand on the scale while it measures your weight.  Once the scale has all the required data, it computes your body fat percentage using BIA technology.

However, the accuracy of such a device has some serious flaws.

First of all, what many people may not realize is BIA scales such as these only send a current up one leg and down the other.  This means that impedance (the metric that all BIA devices use to compute results) is only directly measured in the legs.

The upper body and arms?  Estimated based on the results for the legs.  This means that roughly 40% of your Lean Body Mass is used to determine a body fat percentage that is supposed to account for 100% of your body.

If you feel skeptical about trusting your results from a BIA scale, you’re absolutely correct to do so.

• Handheld BIA Devices

Handheld BIA devices – such as the ones carried by many gyms – are no better, and due to the relatively smaller size of the arms compared to the legs may actually be even more unreliable.  Those devices operate similarly as BIA scales, except instead of measuring the legs, handheld BIA devices send the current from one arm to the other and then estimate everything from your chest down.

This means that these devices are guessing what your overall body composition is based on the composition of your arms.  This can lead to inaccurate results.  If your arms are the most muscular part of your body but you carry the majority of your fat in your midsection, a handheld BIA device will not be able to account for that.

Because handheld BIA devices don’t just report muscle and fat for the arms and give results for the entire body, these results are not trustworthy. Handheld BIA devices only directly measure the arms. Everything else is just estimation and guesswork.

• “Whole Body” Impedance Devices

What about conventional BIA devices, the ones that require you to lie down and have a technician attach adhesive electrodes to the whole right side of your body?  Surely those must be accurate.

Just like scales and handhelds, these devices don’t measure the entire body, even though they might appear to do so.  However, instead of completely missing the upper or lower half of the body like BIA scales and handhelds do, these devices operate differently – but are just as flawed.

In the case of conventional BIA devices, four electrodes are placed on the right half of the body.   The current is sent from the arm, through the body, and out through the leg.  This is somewhat misleadingly referred to as the “Whole Body Impedance” method.

Why misleading? Take a look below:

Although “whole body” might suggest that these devices actually measure the whole body, in reality these machines only directly measure approximately half (usually the right side) and then estimate the remainder.

The core problem with these devices is that they treat the entire body as a single “cylinder.”  This means that when the machine is collecting information, it treats your arms in the same way it treats your trunk/torso; never mind that the trunk’s composition is significantly different than an arm (it contains the internal organs, for instance, and contains a greater amount of Lean Body Mass).

This is a problem when measuring fat and muscle.  Although similarities among genders exist, everybody and every body is different.  Men tend to collect the majority of their fat around their abdomen (android obesity), whereas women tend to collect in the arms and legs in addition to their midsections (gynoid obesity).

What would happen if a particular person didn’t conform to these assumptions? False readings and inaccurate results.

The Future: DSM-BIA

For many people, the devices described above are the only BIA devices they are familiar with.  That’s why, including for those described above, people have very good reasons for dismissing BIA technology. 

However, the industry has recognized the flaws in these BIA devices for some time and, in the last few decades, has responded.

Direct Segmental Multi-Frequency Bioelectrical Impedance Analysis (DSM-BIA) is a new, modern approach to BIA technology that, for the first time, directly measures the entire body.

Unlike any of the previous methods or devices above, devices that employ DSM-BIA do not leave any section of the body unaccounted for.  In order to do this accurately, the body is divided into 5 segments and the impedance for each segment is measured independently.

Once the impedance values for each segment are known, the device interprets the raw data and translates it into useful values such as:

• Body Fat Percentage

• Total Body Water

• Lean Body Mass

Because all 5 segments are measured independently of each other, this allows for more advanced analyses.  The below example shows the amount of Lean Body Mass in pounds in each segment of the body:

Using a device that employs DSM-BIA technology allows a doctor, researcher, or fitness professional to paint a more complete picture of a client’s body composition.  It allows each segment of the body to be measured independently, just as DEXA does, but does it much quicker and more conveniently than DEXA –a major advantage of using a BIA device.

Why Trust This Tech?

DSM-BIA represents a major improvement over all previous BIA devices.  But in order to understand this technology and be confident in the results, you’ll need a brief overview on the basics of how BIA devices work.

All BIA devices operate by sending a small electrical current through fluid, which in the human body, is body water.  The current enters and exits via electrodes that come into contact with the skin.  As the current travels throughout your body water, it encounters muscle cells, fat cells, skin cells, etc.  Each of these has a certain ability to oppose the current slightly as it travels on its path towards the exit point.

Once the current finally reaches its endpoint, it will have lost some of its voltage on its journey through body water.  From here, impedance is determined.  BIA devices, including DSM-BIA devices, take impedance values and translate them into useful information that people can readily understand, like Body Fat Percentage and Lean Body Mass.

If all BIA devices use the same basic principle, then what makes DSM-BIA different?

Consider the example of the “Whole Body Impedance” devices.  While on the one hand they appear to be measuring the entire body and delivering trustworthy results, on the other, they treat the body as though it were a single tube of water, irrespective of body shape.  This means that the opposing effect that the current experiences as it travels through the body gets lumped together as a single impedance value.

This is a problem because due to the width of the arms and legs vs. the width of the upper body, impedance values actually vary quite significantly.  Impedance values for the arms and legs can be 10+ times greater than those for the trunk, as shown below (TR = trunk):

As you can see, the values for the trunk are much, much lower than those of the arms and legs.  A “Whole Body” impedance device would have taken all five of these values and lumped them into a single “whole body” result.  This is where Whole Body impedance gets its name and where it gets its inaccuracy.

As for BIA scales and handheld BIA devices?  A BIA scale will produce results that would look like this:

The handheld BIA device will only be able to measure the arms:

You should notice something: neither of them will measure the all-important trunk.  Only devices that use DSM-BIA paint a complete picture, and only DSM-BIA devices will deliver results that stack up against the gold standards.  All other devices can only offer estimations at best.

An Easier, Better, More Accurate Way

DSM-BIA technology represents the future of body composition analysis and BIA technology.  Older BIA devices have major design flaws that limited their reliability and the reproducibility of their results; DSM-BIA technology has responded to those flaws.

By improving BIA technology, DSM-BIA devices blend the precision expected from gold standard devices with the convenience and ease-of-use provided by traditional BIA devices.  It is possible to have the best of both worlds, after all.