What are our bodies made of?

A mirror can reflect that our bodies are mainly a combination of skin, flesh, bones, and some amount of water. A biology class would teach us that a human body is made of cells which are in turn mainly made of water (about 60% of our weight is water). Ask a chemist and the response might be oxygen. Water is made of two molecules of hydrogen and one molecule of oxygen, but the weight of oxygen is 16 times heavier than hydrogen. And since 60% of body weight is water, then most of the weight of the water (and some of the weight of other molecules) is oxygen. When we ask a physicist, we would be puzzled even more by the answer that our bodies are mostly atoms. And a single atom is composed of nucleus, electrons, and space! (1) Nevertheless, they all agree and point towards the same truth, they simply respond from the focus of their own fields.

The picture describes our bodies in terms of molecules (water, protein, fat, carbohydrate, and minerals). And in terms of elements (oxygen, carbon, hydrogen …etc.) (2)

The point of view most relevant in terms of health and exercise is no doubt the biological view. Therefore, for the sake of simplicity, we can just assume that our bodies are made up of cells and cells together form tissues. So, ‘What type of tissues are we composed of?’ would be our next question to address. When it comes to health and fitness the two most relevant tissues are probably muscle and fat, and a body composition test would measure lean muscle mass and fat mass. To illustrate the importance of both points, someone may have a low body fat mass, but that alone will not indicate excellent health. Since, if the muscle mass is also low, the body would appear to be rather skinny and such body types have their own problems. The opposite of that body type is the obese. The prevalence and problems of the second body type are so significant that they tend to take most of our attention and so, few people would think about why we should not be too skinny either.

The percentages of largest tissues in the body comparison between men and women (3).

Body composition tests

There are many types of tests with varying sophistication and accuracy available. The following is a link to another website that lists several tests and calculations:


Next we will discuss 5 different ways of testing.

DEXA scanning (4)

To take the test, you would have to lie on a ‘table’ while two X-ray beams will scan the body for about 8 minutes. The X-ray beams will have two different energy levels, and one of them will be absorbed more by fat.

This is the gold standard test due to its accuracy. The downside is that it is expensive and not widely available.

Whole Body Plethysmography (Bod Pod) (4)

This involves stepping into a pod that measures your density. And by using constant values for density of fat and for lean mass, the density of each can be determined. The test is highly accurate, though it is not widely available.

Underwater weighing (hydrostatic) (4)

Yet another highly accurate but difficult to find method that measure weight under water along with the density of your body.

Skinfold caliper (4)

This method is reasonably accurate, and easy, though it relies on the skill of the one taking the measurements. The skin and the underlying fat layer are measured using a caliper at four to six locations of the body. The numbers are put to equations to get a final body fat percentage.

A problem with this method is that it would underestimate the fat percentage if the subject has significant localized fat in the abdomen.

Electrical impedance (4)

Myötätuuli has an Inbody machine that uses this technique. To take the test, you are to stand on a scale with as little clothes possible and hold a device in your hands (stretched to your sides). A low current electrical signal is passed through your body. The signal is conducted well through lean mass (bones, muscles, and water) but it is impeded by fat tissue, so the larger the drop in the current, the more body fat there is.

Important note: results are affected by the following factors:

–          Hydration status: The more dehydrated you are (less water in your body), the greater the percentage of fat will appear. It is better to take the test while well hydrated.

–          Skin temperature: affects the reading. Ensure that you are not too warm or cold before taking the test.

–          Localized fat: The signal does not pass the entire body uniformly, but rather specific parts (legs, and if the machine has the devices to be held by the hands, arms as well.) So, the fat localized elsewhere, in places that the current is weak, would be underestimated. Therefore, the test may underestimate abdominal fat.

–          Read a pre-test guide a day before the test. It will tell you what to do to increase the accuracy. The following link show pre-test preparations:


–          To repeat the test exactly as the 1st time, and to eliminate variables, write a small diary that records the history of the test day. The small diary should mention any of the points given in the guideline above that you were not able to follow.

The following is a chart showing what an Inbody test result looks like:

Body fat percentage

There are several standards about how much of our body weight percentage should be fat, and lean muscle. What follows is a table representing the ranges of for body fat percentage by American Council on Exercise (5).Ideal body fat percentage chart (ACE recommendations)DescriptionWomen (%)Men (%)Essential fat10-132-5Athletes14-206-13Fitness21-2414-17Average25-3118-24Obese32 +25 +

Important note: the ranges provide an approximation about our body composition, they are not absolute values. Furthermore, most of the available methods described later will not be able to measure our body fat percentage without error. Therefore, the standards are approximate ranges, the measurement methods are mostly estimates.

Muscle mass percentage (6)

This can also be expressed in terms of fat free mass (FFM), as when we take away the fat, what remains is the lean muscle mass. Lean muscle mass (the term lean means it is fat free) mainly includes our bones, muscles, and internal organs.

Total weight – body fat weight = lean muscle mass

Or body weight percentage – fat percentage = muscle mass percentage (example using obese percentage: 100% – 32%= 68%)

When we look at the table above and use the lowest and highest numbers, we realize that our lean muscle mass is about 60-90% of our body weight, the former in overweight (or almost obese) the latter in athletes.

Why take a body composition test?

What does my body composition says about me?

We often focus on weight as if having too much weight is the issue. But the real problem is having too much body fat, we can be in the right weight (based on our height and age) but have too little muscle mass and too much fat. Hence, the body composition tests reveal more than simple weighing on a scale. If it was just about losing weight, then dehydration can give us the illusion that we have lost ‘harmful’ weight, and delude us into thinking that we are on the right track towards a healthier living. The scale would agree with this, since after dehydration, the scale would say we weigh less. But dehydration is unhealthy and can be dangerous in extreme cases, because our body weight normally has to be about 60% water.

Based on the above arguments we can say:

The body composition tests are most valuable when they are used to measure change or progress.

Since, many of the tests would measure our composition by approximation (it is not certain), if we can repeat the same test exactly the same way, it would be as accurate as the last time. For example, if the 1st test says body fat percentage is 25% and the 2nd states it is now 20%, both measurements alone are just approximates. But both measurements are equally accurate approximates, and so the 5% difference reveals our fitness progress.

Regarding other aspects of our body weight such as – aesthetics (looks), energy (being energetic or tired), mental health (depression, anxiety …etc.) – maybe we do not need a test to tell us about them. The effects of taking care of ourselves (or the lack of it) are felt rather well, and it is such feelings that would drive us to take tests in order to confirm what we already think about our health.

In the end, composition test are helpful for people already training or wishing to start a training program. For the former, it would reveal their current composition and can be used as a record. So, you will have an objective (and reasonably accurate) chart to compare yourself to your past or future self. For those who are about to begin their fitness journey, composition tests are helpful in watching your progress.

About the author: My name is Shalaw. An Iraqi Kurdish, 3rd year sports student (ASL15S),  I have practical training in Myötätuuli. If you have any criticism or questions about the blog, I hope you feel free to express your opinion no matter what it is. I genuinely welcome any feedback given. This is my email address: shalawqader@kamk.fi


  1. Ian Johnston. (2016). What is the human body made of?

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  1. Jen Wherrell. (2015). What should your daily water intake be?

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  1. Mgr. Martina Bernaciková. (2012). Physiology. ISBN 978-80-210-5841-5 (online : HTML)

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  1. Author: unknown. (Year unknown). 5 Ways to Test Your Body Composition

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  1. Marc Perry. (2010). Ideal Body Fat Percentage Chart: How Lean Should You Be?

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  1. Jessica Bruso. (2017). The Average Lean Body Mass

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