Body Composition

Editor’s Note: This post was updated on September 19, 2019, for accuracy and comprehensiveness. It was originally published on August 13, 2015

When it comes to your health, most of the focus is on your levels of body fat and muscle mass, which is important. But not to be overlooked is your body water. Body water, and not your muscle or fat, makes up the largest percentage of body weight. Let’s learn more about this very important element of the human body.

What is Body Water?

Body water is the amount of water content found in your body. Up to 60% of the human body contains water.

Almost every cell in your body contains water: body water makes up 79% of your muscles, 73% of your brain, and even 31% of your bones. Overall your body weight can be 45-65% water.

What should your body water percentage be?

The amount of water within a person is influenced by your age, sex, and fitness level.

When we are born, we are almost 80% water. By the time we reach our first birthday that number drops to about 65%.

A major influence on our body is the amount of fatty tissue and lean body mass that we carry. Lean body mass carries much more body water than body fat.

An adult man will be about 60% water compared to an adult woman that will be about 55% water. If you are physically active, that number will increase depending on your lean body mass.

You might be wondering what is your ideal body water percentage. A better gauge of healthy body water levels is your ratio of extracellular water to your total body water. To understand what that means, we must first define your extracellular water and intracellular water.

What is extracellular water and intracellular water

Like discussed above, your body water can be found inside not only in your blood, but in your muscle tissue, your body fat, your organs, and inside every cell in your body.  To account for all this, your total body water (TBW) can be divided into two basic groups.

• Extracellular Water (ECW)

Extracellular water is the water located outside your cells.  The water in your blood falls into this category. Roughly 1/3 of your fluid is attributed to ECW, and this water is found in your interstitial fluid, transcellular fluid, and blood plasma.

Extracellular water is important because it helps control the movement of electrolytes, allows oxygen delivery to the cells, and clears waste from metabolic processes.

• Intracellular Water (ICW)

Intracellular water is the water located inside your cells.  It comprises 70% of the cytosol, which is a mix of water and other dissolved elements.  In healthy people, it makes up the other 2/3 of the water inside your body.

The intracellular water is the location of important cellular processes, and although it has many functions, a very important one is that it allows molecules to be transported to the different organelles inside the cell.  Essentially, the Intracellular water picks up where the Extracellular water left off by continuing the pathway for fuel to be transported to the cells.

What is a healthy water balance?

When it comes to your body water and you, the most important thing to strive for is balance. Your Intracellular fluid: Extracellular fluid must remain at the same levels with respect to each other.

A healthy fluid distribution has been estimated at a 3:2 ratio of ICW:ECW. If your body water falls out of balance, this can signal changes in your health and body composition. Whether these changes are positive or negative depend on which type of water becomes unbalanced.

What does increased intracellular water (ICW) mean?

Having slightly more ICW than normal isn’t necessarily a bad thing. In fact, it can signal positive changes in your body composition. 

Increased muscle mass is due to the enlargement of the number and size of muscle cells.  When the muscle cells become enlarged, they are able to take in (and require) more ICW in order to power their cellular functions.  Research has shown that resistance exercise can lead to increased intracellular water in humans. Increased ICW as a result of exercise is a sign of increased Lean Body Mass, which is a very good thing and has positive health benefits, including:

• Increased Energy Use

Your Basal Metabolic Rate (BMR) is the amount of calories you burn at rest.  It is the baseline for the calories you need every day in order for your body to operate and maintain daily functions.  With increased Lean Body Mass, your energy needs will increase as a result of a higher BMR. If you don’t increase your daily calorie intake, but increase your Lean Body Mass/BMR, you will create a calorie deficit – which can lead to body fat loss.

• Increased Strength

Your Lean Body Mass is sometimes described as your fat free mass.  Your Lean Body Mass accounts for all your weight due to water, muscle mass, bone, and protein.  One of the easiest ways to influence the amount of Lean Body Mass you have is to increase your muscle mass.  Generally, increased muscle mass leads to increased strength.

• Increased Immune System

Increased Lean Body Mass through exercise has been associated with increased immune system functionality.  This will help your body fight off illnesses more easily.

What does excess extracellular water mean (ECW)?

If your ECW increases in relation to your ICW, this is something you should take special note of.  Unlike ICW, you do not want to see your ECW increasing beyond normal levels. Excess ECW can indicate health risks, including:

• Inflammation

During inflammation, the body sends additional blood flow to the damaged area.  This causes an increase of extracellular water in a particular area. Inflammation occurs when part of the body gets damaged or bruised and is a normal bodily response to injury.  This is called acute inflammation, and is a temporary increase in ECW.

Chronic inflammation, however, is something more serious that isn’t always readily detected. It is marked by long-term swelling/ECW increases caused by cellular stress and dysfunction. Chronic inflammation can lead to serious diseases if allowed to persist over time, including renal failure, cancer, and heart disease. including renal failure, cancer, and heart disease.

• Renal Disease (Kidney Failure)

One of the kidneys’ major functions is to filter your blood and remove toxins produce in the body.  One important substance that the kidneys filter out is sodium, an element that is found in salt.

When your diet includes more sodium than your kidneys can filter out, which occurs in people who have failing kidneys, your extracellular water levels will increase.  In some cases, this increased extracellular water shows in visible swelling throughout the body and is a condition known as edema. Edema can cause additional strain on the body by contributing to weight gain, blood pressure, and other complications.

• Unhealthy Fat Mass Levels (Obesity)

Obese individuals are characterized by having too much body fat, which among other things, leads to body water disruption due to excess ECW.  This is because excess visceral fat can trigger production hormones that can lead to the disruption of a bodily system called RAAS.  This excess ECW causes stress in the body due to its effects on the internal organs, which can exacerbate obesity and cause a dangerous cyclic effect.

How to find your total body water?

Since it’s so important to keep an eye on your fluid balance, you’ll need to know how you can determine yours. There are two major methods to measure and determine your fluid levels.  These are the dilution method and the BIA method.

The dilution method involves drinking a known dose of heavy water (deuterium oxide) and allowing it to distribute around the body.  Once the water has had time to settle, the amount of heavy water is compared with the amount of normal water. The proportion will reflect the amount of total body water.  To determine ECW, sodium bromide is used instead of heavy water.

The dilution method is recognized as a gold standard for measuring total body water; however, these tests would need to be done at a hospital under the guidance of a trained physician.  This test takes several hours to complete during which any fluid of any type going in or out of the body has to be carefully recorded.

For these reasons, you’re unlikely to have this test performed unless your doctor needs to know your total body water with absolute certainty because of a serious health complication.

The second, more accessible method to determine body water content is bioelectrical impedance analysis (BIA).  For most people who do not have serious medical issues, this method is much more practical than the dilution method.

A small electrical current is applied to the body, and the opposition that current experiences (impedance), is measured.  From that impedance result, a BIA device can report your body water percentage. Advanced BIA devices are able to reflect the difference in Intracellular and Extracellular water as well, which can reveal the ICW:ECW balance.

Bringing Yourself Back Into Balance

Maintaining a balanced ratio of approximately 3:2 is ideal for optimal health.  If you find that this ratio is beginning to fall out of balance, there are some things you can do.  Fortunately, these tips aren’t anything you already haven’t heard before: maintaining a healthy diet, staying hydrated by drinking enough water, and exercising regularly.

Avoiding excess ECW is ideal.  From a dietary standpoint, one simple change that can work to reduce excess ECW is reducing the amount of sodium (salt) in your diet. Sodium is located primarily in your ECW, and when excess sodium is introduced into the body, the body’s natural response is to draw water out of your cells at the expense of your ICW.  Reducing your sodium intake has a number of positive health benefits, so this tip can be considered simply a best practice for optimal health in addition to being a tactic for reducing high ECW.

On the flip side, increasing your ICW can be achieved by increasing your Lean Body Mass/increasing muscle mass through exercising.  As the muscle cells increase in size, they will require more water to maintain their function. Exercise has the additional benefit of combating obesity, and as fat mass is reduced, ECW increases due to obesity will decline over time.

As you can see, body water can be an important indicator of your overall health.  Without a healthy ICW:ECW ratio your body will begin to have problems.

The best thing you can do for proper body water balance is to maintain a healthy lifestyle. If you can achieve a healthy lifestyle, your body water will fall into balance naturally.  The first step would be to find out where your body water levels are today, so you can start planning for a healthier life now.

Just like any other industry, the world of health and fitness comes jammed with lots of technical words and terms once you go past a surface level understanding. It can get confusing fast, and terms can get jumbled (Lean Body Mass? Lean muscle? Which is it?).

This is really unfortunate.  Body composition analysis allows you to understand your body in a much clearer way, and it gives you insights into your health that you would have otherwise never known.

Here, we’re going to demystify these technical body composition terms for you and give you a basic understanding of how they are relevant to you.  You can think of this as part glossary, part action guide.

A Guide to Basic Body Composition Terminology

Percent Body Fat (Body Fat Percentage)

If you walk away with just one new term under your belt, walk away with this one: Percent Body Fat.  It’s a reflection of how much of your weight is made up of body fat and is calculated by dividing the weight of your body fat mass by your total weight. It is a deceptively simple metric but has an awesome number of highly relevant uses.

What You Can Learn From It:

Percent Body Fat is always expressed, obviously, as a percentage. This percentage can then be applied to set percent body fat ranges. While there are no official, set-in-stone ranges like there are for BMI, you’ll find that the healthy ranges tend to hover around 10-20% percent body fat for men and 18-28% for women. Organizations offering set ranges include ACSM and ACE; you can view theirs as well.

Lean Body Mass (aka Fat-Free Mass)

Another very important term to be familiar with is Lean Body Mass, sometimes used interchangeably in conversation with Fat-Free Mass.  As that term implies, Lean Body Mass is the weight of everything in your body that isn’t fat. This includes your muscles, organs, bones, and body water.

While it’s important to understand what Lean Body Mass is, it’s equally important to understand what it isn’t. Lean Body Mass isn’t the same as muscle; rather, Lean Body Mass is a collection of different types of body tissues that includes muscle.

What You Can Learn From It:

Lean Body Mass plus your Body Fat Mass makes up your entire body weight.  If you have your Lean Body Mass value in pounds, you can subtract this number from your total body weight to get an approximation of your Body Fat Mass. Divide that by your body weight, and now you’ve got your percent body fat.

Another interesting attribute about your Lean Body Mass is that it is closely related to the total number of calories your body needs each day. Your Lean Body Mass forms the core of your metabolism, and you can use this number to help you determine your unique dietary needs. No more basing your diet off the 2,000-calorie diet, which in reality is a poorly fitting, one-size-fits-all approach to food intake.

Skeletal Muscle Mass

When people talk about their muscles, they’re more than likely talking about Skeletal Muscle Mass.  Skeletal muscle is one of the three major muscle types (the others being cardiac and smooth) and is the type that governs all the movements you can consciously control: everything from typing out a text to deadlifting a 300-pound barbell. It’s also the muscle group you’re growing when you exercise.

Value To You: Increased Skeletal Muscle Mass typically translates into increased strength.  If you’re trying to build up your body and grow in size, this is the value you’d want to track and see increases in over time.

However, muscle isn’t just for strength.  Muscle is composed of primarily protein and can act as a “protein bank.” Why would you want a protein bank? When your body gets put under severe stress – such as in a traumatic injury – the recovery process is triggered and requires additional protein, up to four times the amount in some cases. When it’s not able to get that amount of protein from your diet, your body will start getting what it needs from the protein bank – aka your muscles.

Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate, or BMR, is the number of calories that your body requires to maintain its Lean Body Mass. It’s a huge component of your overall metabolism.  Someone with more Lean Body Mass will have a higher BMR than someone with less BMR. It’s the reason why a 250-pound NFL linebacker needs to eat more than a 150-pound sedentary adult – the linebacker has far more Lean Body Mass.

Value To You: Outside of your Percent Body Fat, if you learn a second thing today, learn the value of your Basal Metabolic Rate.  Used properly, your BMR can help you make a nutritional plan designed for either fat loss or muscle gain by helping you understand how much energy (read: calories from food) your body needs.

By multiplying your BMR with an activity factor, you can get a general estimate of your Total Daily Energy Expenditure (TDEE). Using your TDEE as a baseline, you can start to craft nutritional plans for yourself based on what you want to do with your body composition.

Want to lose fat? Create a caloric deficit by decreasing energy in (food) and increasing energy out (exercise). Looking to increase muscle? Eat more than your TDEE requires and use that extra energy to hit the weight room and build new muscle.

Body Water

You may have heard somewhere along the line that “humans are mostly water.”  Generally speaking, that’s true. Your Body Water includes all the water in your body, everything from the water in your blood, to the water in your organs, to the water inside your bones.

Your body water is usually subdivided into two types: intracellular and extracellular. Intracellular (inside the cells) includes the water in your organs, muscles, and such, composing 2/3 of your total body water. The remaining 1/3 is the extracellular (outside the cells) water and includes the water in your blood.

Value To You: Hopefully, you never have to worry about body water.  If you’re generally healthy, your body maintains a healthy balance of intracellular to extracellular water (at a ratio of about 3:2). It’s when this balance becomes broken that monitoring your body water becomes very important.

People who have severe health problems, particularly those with kidney failure, will be unable to rid their bodies of extracellular water.  This causes buildup of body water requiring removal through procedures such as dialysis.

Dry Lean Mass

If you remember, Lean Body Mass includes everything that’s not body fat, which would mean it includes body water.  When you take out all the water (becoming “dry”) what remains is known as the Dry Lean Mass. Lean Body Mass – Body Water = Dry Lean Mass. What this amounts to is the protein content of your muscles and the mineral content of your bones. Much of your Dry Lean Mass will be found in those two places.

Value To You: Why would you ever care about your Dry Lean Mass? Because you want to track real, physical changes in your body.

Lean Body Mass contains body water, and your body water levels can be influenced by many different factors: whether you’ve recently worked out for instance, or whether you are low on carbohydrates. Changes in body water are technically changes in Lean Body Mass (another reason why Lean Body Mass isn’t the same as muscle).

However, when you build muscle, you’re actually building new physical protein stores – and that’s reflected in your Dry Lean Mass. An increase in Lean Body Mass may signal muscle growth, or it may not. By contrast, an increase in Dry Lean Mass is a much stronger indicator that you actually grew muscle.

Visceral Fat

There are two major categories of body fat. Subcutaneous fat is the fat under your skin, and it’s the type of fat that you can see.  The second type of fat is called visceral fat. This type of fat collects inside your abdomen and wraps around your internal organs.

Why It’s Worth Knowing About: Just because you can’t see it doesn’t mean it’s not there. In the case of visceral fat, if it is there, you’ll definitely want to know about it. That’s because visceral fat is not just extra pounds – it’s an active organ that secretes harmful hormones in your body that triggers perpetual inflammation. The more visceral fat you have, the greater risk of inflammation. Inflammation over time can put undue stress on the heart, leading to cardiovascular problems later on.

Get Tested and Know Your Numbers

Hopefully this has cleared up some of the more complicated body composition terms. This has been a basic overview designed to give you the essential information about your body composition and how it applies to you, but there is a lot more to know.

To learn more, you can check out the following articles that examine these topics in closer detail:

• Percent Body Fat
• Lean Body Mass
• Body Water
• Basal Metabolic Rate
• Visceral Fat

Knowing your numbers and having them checked from time to time will help you understand your health in ways you never have before. Greater understanding of body composition can help you also make healthy lifestyle choices, such as deciding to lose weight or changing your diet.

Get tested, know your numbers, and live a better life!

Editor’s Note: This post was updated on August 14, 2018, for accuracy and comprehensiveness. It was originally published on June 16, 2015.

• Detailed body composition analysis uses the 4C Model that breaks the body into body water, protein, minerals, fat. 
• Fat and muscle may weigh the same, but muscle is significantly denser than body fat.
• The four common methods of measuring your body composition are calipers, hydrostatic weighing, DEXA, and BIA.

At your recent physical, your doctor mentions that you should get body composition tested. You’ve overheard trainers tell their clients how much their body composition has improved. You keep seeing the term pop up on fitness or health blogs (like yours truly). You may smile and nod knowingly when it comes up in conversation, but secretly, deep down, you’ve always been thinking:

“What exactly is body composition?”

If this sounds like you, fear not, you’re in the right place.

Body composition analysis is a trending topic in health, medicine, and fitness because it is a whole body assessment that gives you the blueprint for improving your health.

Think about when you take your car into the shop for an inspection. In order to examine the condition of the car, the mechanic opens the hood, checks the fluids, and inspects the working components.

Body composition analysis is the same idea, except instead of examining your engine oil level or testing the battery life, you are getting a measurement of your fat, muscle mass, and body water levels.

By “looking under the hood” and understanding what areas you need to improve on in order to achieve a healthy body composition, you will look and feel so much better!   

This Is What You Are Made Of

Let’s start with the basics. The first thing to know is that there are several different models of body composition. Below we will explore the two most common models.

2C Model

1. Fat Mass

The substance everyone seems to always have too much of and is always doing their best to get rid of. However, body fat is necessary for the body to function: Body Fat allows the body to store energy, protects internal organs, acts as an insulator and regulates body temperature, among other things. Nobody can have 0% body fat, and maintaining body fat percentages lower than 4% is generally regarded as inadvisable for long-term health.

2. Fat-Free Mass (FFM)

Fat-Free Mass is what it sounds like – all the mass in your body that is not attributed to fat. Your FFM contains a variety of different components, all your internal organs, skeletal muscle mass, water, etc.  Everything that is not fat can be lumped into the category of Fat-Free Mass.

From these two values, your body fat percentage can be deduced by dividing your fat mass by your total body weight. If your goal is to determine only your body fat (not lean body mass, muscle mass, etc), procedures that utilize the 2C method can be used to determine your body composition.

4C Model

For a more detailed body composition analysis, you have to use methods that break the body into more components, such as the 4 component (4C) model.  

This breaks your body into the following four components:

1. Body Water

Adults are more than 50% water. Your body fat, muscles, blood, and other bodily fluids all contain water.  These components can be further broken down into the water contained inside your body’s cells (intracellular water) and the water outside your cells (extracellular water).

2. Protein

This is a reflection of the protein contained in your body’s muscles.

3. Minerals

Your body contains minerals which are primarily contained in two places: in the bloodstream and inside the bone tissue.

4. Fat

Here are some less common (but important) body composition terms:

• Dry Lean Mass (DLM): Your Dry Lean Mass is the combination of the weight attributed to the protein and the bone mineral in your body.
• Lean Body Mass (LBM): Your Lean Body Mass is the combination of your DLM and body water.
• Skeletal Muscle Mass (SMM): Not to be confused with DLM or LBM, Skeletal Muscle Mass are the muscles that are connected to your bones and allow you to move. These are all the muscles that can be grown and developed through exercise (your pectorals, biceps, quadriceps, and so on).

These terms together give you a more sophisticated way to think about and approach both your body weight and your health. Put simply, you’ve got to know your body composition if you are serious about reaching your health goals and improving your quality of life.  Without knowing what you’re actually made of, you can only guess at how much muscle and body fat you actually have. Guessing leads to frustration, frustration leads to indifference, and indifference leads to quitting.

What’s So Important About Body Composition, Anyway?

At this point, you might be a little overwhelmed with these new terms, and think, “Thanks, but no thanks. I will just stick with something traditional and easy like Body Mass Index.”

But the Centers of Disease Control and Prevention (CDC) has found that while BMI can be used to categorize people into weight categories that have a higher chance of developing health complications, it is not an accurate tool to measure body fatness or assess health because it does not differentiate what your body weight is made up of.

The reason why that is important is that although fat and muscle may weigh the same, muscle is significantly denser than body fat. That means that 15 pounds of muscle takes up much less space than 15 pounds of fat.

So what does this mean for the average person who is looking to stay healthy?  Well, if you’re simply just that: average (neither athletic nor overweight), then BMI can be a fairly good indicator to measure if you are at a healthy weight.  But if you are even a little bit athletic, or if you lead a fairly sedentary lifestyle, BMI can be misleading.

Take a star NFL tight end. At 6’6”, 262 pounds he would have a BMI of 28.8 – and according to the World Health Organization, an individual with a BMI score of 30 is classified as “obese.” But you wouldn’t consider him almost obese when you see him sprint away from NFL defensive backs.

And when we look at this muscle and body fat levels, his body composition results agree.

The muscle mass and percentage muscle mass measurements show an individual with high Skeletal Muscle Mass and low Percent Body Fat (12.7%).

The reason his body weight is so high is that more than half of his body weight is made up of muscle. Although BMI may not be an accurate measurement tool for rich professional athletes, you might be wondering what does this have to do with me.

Well if you are like 150 million American office workers who aren’t getting enough exercise, BMI may be giving you a false sense of security.

For example, picture your average office worker as 5’4” and 140 pounds for a BMI score of 23.1: solidly in the “normal” BMI range. This person may want to improve their fitness level, but it’s not a high priority because her BMI is still pretty good.

Sedentary adults working in offices who do not exercise are known to lose Skeletal Muscle mass, especially in their legs. Coupled with a similar increase in body fat   This can lead to high body fat percentages, even in individuals with “normal” body weight and BMI. This condition is called skinny fat, and because of our reliance on body weight measurement and BMI, it often goes undetected.

The muscle mass and percentage muscle mass measurements show an individual with low Skeletal Muscle Mass and High Percent Body Fat (31.1%).

These individuals are at risk for some of the same health complications as people who are visibly overweight, with BMI values above 25.  These health complications can include cardiovascular disease, high blood pressure, diabetes, and more.

It then makes sense that in a Canadian study of 50,000 people, it was found that a low BMI did not necessarily correspond with a lower mortality rate.

How Can You Check Your Body Composition?

Hopefully, by now we have convinced you the importance of using something more advanced than a weight scale or BMI. Luckily, there are many methods to determine your body composition.  Some are quick and easy but provide basic information only. Some are lengthy and expensive and require the assistance of a trained technician to administer a test.

Here are four common methods:

Skinfold Calipers

Image Credit: Flickr

This is a method that many people have encountered in their local gym.  Calipers are widely used because they are portable, easy to use, and can be administered by almost anyone as long as they have had proper training and sufficient experience.

Calipers work by pinching external body fat in several places around your body and measuring how much skinfold can be grasped by the caliper’s arms.  These results are taken and used in mathematical calculations, which determine the fat mass in your entire body.

If this sounds simple, that’s because it is.  Calipers are an example of 2C body composition analysis.  Calipers will tell you how much fat you have, but that’s about it.

The other thing to be aware of when you are using calipers to test your body composition is that the accuracy of your results may vary across tests, and the reproducibility (having consistent test results when back-to-back testing) won’t be as high as tests performed on medical-grade machines, which are designed to reduce variance across tests and increase accuracy.

Hydrostatic Weighing

Image Credit: Chemistry Land

Hydrostatic weighing (also known as underwater weighing) calculates your body fat percentage using you underwater body weight. To get your underwater weight, you first need to expel all of the air in your lungs and then submerge yourself in a pool while sitting on a special scale. Your underwater weight is compared with what you weigh on land, and these numbers, together with the value of the density of the water in the pool, are put through a series of calculations.  These calculations produce your body fat percentage.

When done properly, hydrostatic weighing is a very precise method for measuring your body fat percentage, and it is often regarded as “Gold Standard” for body composition analysis.  However, just like calipers, hydrostatic weighing cannot report anything beyond body fat, like skeletal muscle mass, body water, and dry lean mass.

To get a hydrostatic weighing test performed, you will need to make an appointment at a facility such as a university or high-end sports complex that has built a hydrostatic weighing pool and a trained staff.

Dual Energy X-Ray Absorptiometry (DEXA)

Image Credit: Nick Smith photography

DEXA (sometimes abbreviated as DXA), is a medical test that involves lying on a table while a machine sends X-rays through your body and measures the difference in the amount of energy initially sent through the body and the amount detected after it exits the body.  Although DEXA was originally designed to measure bone density, it is now used to measure body fat and muscle mass.

Along with hydrostatic weighing, DEXA scans are regarded as a “Gold Standard” for measuring body fat percentage.  Unlike calipers and underwater weighing, DEXA scans have the ability to measure the body segmentally, scanning each arm and the trunk separately in order to accurately measure fat mass, soft lean mass, and bone density in each segment.

In order to get a DEXA scan performed, you will typically need to make an appointment with a hospital or clinic that has a DEXA device. You may need to do some research; because of the cost, not all hospitals and clinics will have a DEXA machine.

Bioelectric Impedance Analysis (BIA)

Bioelectrical Impedance Analysis (BIA) works by sending a small electrical current into a person and measuring the opposition of that current (impedance) as it travels throughout the body’s water. Once impedance is measured, body composition is calculated.  Unlike other methods, a technician does not always need to be present at a BIA test, and you can use BIA devices with just by following the directions on the device.

BIA devices range widely in quality and accuracy, and you should be aware that not all BIA devices test the entire body.  Consumer body composition scales, use BIA to directly measure leg impedance only and use estimations to determine results for the upper body.  Handheld devices only directly measure arm impedance and estimate results for the lower body.

By contrast, modern, medical-grade BIA devices are able to measure the entire body directly and can be extremely accurate –  with measurements that are closely aligned with “Gold Standard” procedures – without the complications that those procedures sometimes entail.  The most advanced BIA devices are even able to perform segmental analysis.

Because BIA measures work by measuring body water, a lot of useful information can be reported.  Although nearly all BIA devices will tell you your body fat percentage, some devices can go much further and report the body water weight, skeletal muscle mass, lean body mass, and much more.

Hopefully, this helps you a general understanding of body composition.  Knowing your body composition is the first step towards improving it, so if you’re able, schedule a body composition test soon. Your body composition test results can aid you immensely in understanding your weight, improving your overall health, and helping you achieve your fitness goals.

For a recap, check out this video:

BMI, or Body Mass Index, has long been held as the standard for measuring obesity . But for many years now, BMI has been coming under increased pressure – scrutinized and criticized for its failure to tell the whole story. Critics say BMI is too broad, its results are inaccurate, and it doesn’t really tell you anything about your body composition.

Now, more and more industries and organizations are moving away from BMI toward a more accurate, comprehensive, and realistic measurement: body fat percentage.

BMI: A Brief History

Your BMI is determined by dividing your weight by the square of your height. A BMI in the “normal” range falls between 18.5 and 25. So if you’re 5’10” you’ll want to weigh about 130-175 pounds. Simple, right? But the problem with BMI lies within that simplicity. The formula fails to account for a number of important factors. One of the reasons BMI fails to account for anything more than just height and weight is because it was never really designed to do more than that.

BMI was developed in the early- to mid-1800s by a Belgian scientist named Adolphe Quetelet. He envisioned a simple way to determine whether or not a person was overweight. For almost 200 years, it has remained the standard that medical professionals often turn to when researching obesity.

In fact, The World Health Organization currently uses it as the standard for recording obesity statistics and has done so since the early 1980s. That’s because on a macro level, BMI is still good for examining trends. It works for when you want to get the general feel for the overall health and well-being of a city or a nation. However, BMI should never be used to assess health on an individual level. There are simply too many flaws in the system.

One of the most famous examples of the flaws in the Body Mass Index system is Arnold Schwarzenegger. When the former California Governor was in the prime of his bodybuilding career, he was 6’0” and weighed 235 pounds. This gave him a BMI of 31, putting him in the obese range.

Anyone who has ever seen a photo of a young Arnold knows that, while there are many words that can be used to describe his physique, “obese” is definitely not one of them.

Enter Body Composition

So if BMI provides an incomplete health and wellness picture, how do you get the full picture? Body composition. Body Composition is the amount of fat, Lean Body Mass, etc., in your body. When you’re measuring leanness, you must account for these factors; it can’t be as simple as height and weight.

Body composition is essentially how much of your body is made up of fat vs. lean mass. If you’re interested in living a longer, healthier life, body fat percentage matters more than your weight, and much more than your BMI.

And remember, body fat percentage isn’t just about looking good, it’s about living longer. High fat percentage increases the risk of high cholesterol, which increases the chances of a heart attack.

How is body composition determined? There are many ways to assess body composition, and they vary widely in cost and accuracy. Let’s start with one of the most basic assessments.

The Tape Test. A Thing of the Past?

In recent weeks, the U.S. Army has come out in favor of a more comprehensive way to examine the health and well-being of its soldiers. This summer, the Army division charged with height and weight standards is undergoing a complete overhaul. One of the things that will receive a lot of attention in the review is the controversial tape test.

The Army Body Fat Calculator determines your fat percentage by taking two measurements, usually done with measuring tape. It asks for your gender, age, height. And then you measure your neck just below the larynx, and your waist at the level of the belly button. Combine those five factors and you come up with the Army’s definition of body fat percentage.

But there are problems with the test. Soldiers have long-contested whether the tape test is the best way to measure body fat. Specifically, women, bodybuilders, and “people with naturally thin necks or wide hips” say the test isn’t fair. The tape test has been reviewed in the past, and all the reviews usually say something along the lines of: “it’s not perfect, but it’s the best we can do for now.”

Sound like anything familiar?  Like the tape test, BMI may not be perfect, but it is quick and easy. However, the tape test isn’t the only way to determine body composition, and for that, we turn to the world of professional sports.

A New Way of Thinking

Body composition is a new term that’s being thrown around at Green Bay Packer press conferences as of late. The Packers’ star running back Eddie Lacy has had his weight in the spotlight for years now. At a recent press conference, Packer Coach Mike McCarthy was asked about Lacy’s weight. He told reporters that he is no longer concerned with Lacy’s weight. “It’s based on his body composition,” McCarthy said.

The Packers use what’s called a DXA scan, or dual-energy X-ray absorptiometry, to determine their percentage of muscle and fat. The technology was originally used to measure bone density, but the same process can be applied to the rest of the body to provide an accurate picture of fat versus muscle. Of course, not everyone has the kind of budget the Packers are working with, so a DXA scan might not be in your future. So what are some other options for measuring your body composition?

Body fat calipers are a common option, and are often used by personal trainers. Also referred to as skinfold calipers, these hand-held machines pinch an area of your body and measure how thick the fold of fat under the skin is. The measurements are taken at anywhere from 3 to up to 11  different places on your body and can provide a quick and dirty body fat percentage measurement (especially when only 3 sites are used).

However, a second, far less intrusive method is bioelectrical impedance analysis, or BIA. BIA sends an electrical signal through your body. Based on how that signal interacts with the fat, muscle, and other elements of your body, the device is able to separate your weight into – at a minimum – Fat Mass and Lean Body Mass. More advanced devices can go further and provide outputs for Skeletal Muscle Mass, Visceral Fat, and Body Water.

Regardless of how you measure it, it is becoming clear that body fat percentage is a much more accurate measurement of your overall health than BMI.

So What Do I Do Now?

Once you start thinking of your weight in terms of what it is made of up (i.e. body composition), you will begin to get a sense of where you fall on the spectrum. You will also be presented with one of two options to begin your journey to a healthier you: in short, you will either want to increase your lean body mass or decrease your fat mass. Essentially, you’re looking to change your body composition, something also known as “body recomposition.”

If you have a high body fat percentage, you will want to focus on decreasing your fat mass. This can be accomplished by burning more calories a day than you take in. When you take in fewer calories than your body uses in a day, you encourage it to draw the needed energy from where energy reserves are stored – your fat cells.

Conversely, if you’d prefer to work on building strength and size before targeting your fat, focusing on developing your Lean Body Mass. The best way to accomplish this is by participating in a resistance training program and focusing on proper nutrition to encourage muscle growth and development.

Although BMI has been used for a long time to assess your weight (maybe even your doctor still records your BMI at checkups), if you’re really serious about improving your health and wellness, it’s time that forgot about your BMI and find a way to track and trend your body fat percentage.

Body composition is not a fad, nor is it a trend in the health and wellness industry. Despite being somewhat of a “new kid on the block” in terms of awareness among the general public, body fat percentage and Lean Body Mass have been well-studied and discussed in the scientific literature for decades.

But the winds of change are here: whether it’s the NY Times running a series of pieces on BMI’s failings last year, or the Mayo Clinic publishing exciting new research on the impact of body composition on your health just a few months ago.

Figure out your body fat percentage, and you’ll be well on your way to a healthier, happier you.

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Randy Miller is a freelance writer who lives and works in Sacramento, CA. To get in touch with Randy about this article, you can find him on his website, www.randymiller.net.