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Editor’s Note: This post was updated on September 14, 2018for 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 Body Water: Percentage and Ratios You Should Know

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 BWA 2.0 

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.