Anna Evans

Why You Should Know Your Body Composition

What is body composition, why is it more telling than BMI, and why do we keep focusing on fat?


We know that being overweight is the key risk factor for developing many diseases, and being underweight is dangerous too. Aiming for a healthy weight to stay well is common practice. But do you know what is actually ‘healthy’ for you? Each body is different and sometimes the number on a bathroom scale may be not enough to see the whole picture.

For example, someone who looks skinny may have too much visceral – hidden – fat which is dangerous for the inner organs. And someone who looks ‘heavy’ may struggle with losing kilos or pounds without knowing that they have quite a lot of muscles. Of course, these are specific examples, but finding out body composition may benefit everyone, no matter if you are trying to lose weight or improve your fitness performance. Let’s find out why it’s so important and how to do that.

What is body composition?

Body composition is the measurement that shows the proportion of fat and fat-free mass in a body. More simply, it shows the ‘ingredients’ of your body and the percentage of each of the elements.

What does your body consist of?

There are different levels to what your body consists of: atomic, molecular, tissue, etc. When talking about body composition, people usually refer to these components:

  • Water

  • Proteins (Including Muscles)

  • Minerals (Including Bones)

  • Fat

Different ways to measure body composition


There are several ways to determine the ratio of elements in your body. Some of them are not available to average people but can be done in medical centres.

1. Skinfold Callipers. This method is also known as a ‘pinch test’. The callipers pinch different parts of your body to measure the thickness and determine the percentage of fat. It’s very common and simple but it does not provide the most accurate results and may be a poor solution for those with uneven fat distribution.

2. Dual Energy X-Ray Absorptiometry (DEXA). This method uses two different X-rays to accurately measure bone density, muscles, and body fat.

3. MRI (Magnetic Resonance Imaging). This method uses a high-strength magnet to scan the body and measure skeletal muscles and fat – it can even distinguish between visceral and subcutaneous fat.

4. Hydrostatic weighing. This way can help you find out how much fat you have. The process is pretty much in the name – you weigh yourself in water. Your body fat will float and your lean tissue will sink.

5. Bioelectrical impedance. This way of measuring your body fat sends electrical currents through your body and measures how fast they travel. This method is cheaper than skin callipers, but it is not always accurate. It is best for monitoring changes in your body fat over time.

Body composition vs BMI

As we mentioned earlier, everybody is unique and two people with the same weight and height may have completely different health conditions because their body compositions are different.

Someone can have a ‘healthy’ BMI (Body Mass Index) while being actually unhealthy and lacking muscles. That is the reason why the BMI method seems flawed and outdated nowadays.

Using BMI is still convenient due to the simplicity of the measurement, and it can give a general understanding if the person is healthy, but it is not accurate and should be used as a complex measurement. In this case, finding out your body composition is a much more efficient way of monitoring your health and fitness.

Not all fat is the enemy

In many cases, body composition comes down to checking just how much percentage of fat is inside one’s body and that’s not the best way to do that. Despite the very popular misconception, keeping a healthy weight doesn’t mean your fat should be near zero.

Yes, having too much fat is dangerous, but our bodies were equipped with fat for a reason. You must have an essential fat that plays a great role in keeping us alive, for example:

  • It stores energy

  • It provides insulation

  • It regulates body temperature

  • It carries fat-soluble vitamins

  • It gives protection to your organs

  • It works as a building component for cell membranes

  • It helps to produce hormones, including estrogen and testosterone

  • It produces leptin, a protein that regulates appetite

However, there is another dangerous type of fat – visceral fat, which is stored within the abdominal cavity. Not only does it give people an ‘apple’ shape and make their bellies stick out, but this type of fat has potentially toxic effects on the body. It secretes a variety of chemicals, which can be harmful to organs such as the liver and intestines.

Though it makes up approximately 1/10 of all the fat stored in the body, it is not visible like subcutaneous fat which is stored right under the skin, making it hard to detect until its negative impact has already been felt.

The healthy fat percentage range

According to The American College of Sports Medicine (ACSM), there are different levels of fat percentage for men and women.

Different levels of fat percentage for men and women, stats Source: ACSM

Essential fat – a minimal amount of fat that a person can have for the body to function normally:

– Men: 3-5%
– Women: 8-12%

For health purposes – the satisfactory amount of fat needed for normal well-being:

– Men: 12-23%
– Women: 17-26%

Athletes – the fat percentage desired for the best athletic performance:

– Men: 5-13%
– Women: 12-22%

Important note

It’s completely normal that women have higher fat percentages than men, due to different hormonal functions and potential childbearing.

Muscles need attention too


It is important to understand that measuring body composition is not intended to just reveal body fat. It should describe the ratio of fat to other parts and help you make decisions on how to improve your diet and lifestyle to have healthier proportions of all the components, including muscles. When checking weight on a bathroom scale, many people are hoping to see the numbers go down, but how do you know if you are losing excess fat and not muscles?

Keeping the proper muscle mass is critical for well-being because muscles let us move, eat, speak, and breathe. They let us survive by controlling our heartbeat, digestion, and other vital processes.

Unfortunately, as we age, our muscles start to decline in mass. This process is also known as sarcopenia. It starts around 40 years of age and it heavily affects people over 60. Losing muscles reduces the ability to perform ordinary tasks, increases the risk of injuries, and highly impacts the quality of life.

Monitoring your body composition shows the dynamic of your muscles’ growth or decline. It can make the difference between tracked progress and the assumed state of things.

Let’s sum up: Why body composition is so important

Understanding your body brings great advantages. It allows for more precise and accurate monitoring of change and the development of a stronger muscular system. It also offers the unique opportunity to set personalised health-related goals tailored to their current percentage of fat and muscles. By knowing their own bodies people can focus not solely on weight loss, but on excessive fat loss instead. It can help to achieve long-term health benefits and fitness instead of a quick loss of several kilos or pounds.

Hungry for knowledge? Here is more

In this video, Dr. Evan Matthews, a cardiovascular and exercise physiologist, gives a detailed explanation of different ways to find out body composition. Watch it to decide which way is the best for you.

Healthypedia FAQ

This measurement shows the ratio of fat and fat-free mass. Simply put, it shows the ‘ingredients’ of your body and the percentage of each of the elements. Knowing your BC can help to achieve long-term health benefits, and cardiovascular fitness instead of a quick loss of several kilos or pounds.

In this day and age, there are several ways to determine it. The most common are the Skinfold Callipers method, Dual Energy X-Ray Absorptiometry (DEXA), MRI (Magnetic Resonance Imaging), Hydrostatic weighing, and Bioelectrical impedance.

The satisfactory amount of fat needed for health is 12-23% for men and 17-26% for women. Please note that it’s completely normal that women have higher fat percentages than men, due to different hormonal functions and potential childbearing.

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