When embarking on a fitness plan, a lot of us get our body fat percentage measured.  But how many of you know what that means…?

It was between 600 and 300BC that the Ancient Greeks began a systematic study of mathematics.  It was prior to that, that we had a concept of measurement i.e. me can’t throw spear at antelope – too far.  Me can’t carry antelope home – too heavy. Me can’t get antelope through cave door – too wide”.  But once numeracy was created, we became obsessed with putting a number on everything.  Time, distance, weight, temperature, noise, speed etc.  Everything needed to be quantifiable, and body fat didn’t escape that need.

What is body composition?

Once measured, we present body fat as a percentage, which is essentially a ratio of everything you have in your body classified into two categories – fat mass, and fat-free mass.  There are numerous types of different fats in our body and the two main categories of fat are subcutaneous fat (which is surface fat that sits just under the skin.  This is the visible fat), and visceral fat (which is the fat that sits around your organs).   Visceral fat is the biggest health risk but is also the easiest to lose.

So what is fat’s role in your body?

Well it insulates your body, cushions your vital organs and it can be (and often is) stored so it can be converted into energy when needed.  It’s also used to build new cells and is critical for normal brain development and nerve function – every single cell in your body is comprised of fat and your brain is 60% fat.  Fat is also needed to carry and help absorb fat-soluble vitamins such as Vitamins A, D, E & K.  All in all, fat is essential for us to stay alive.

So what would be the benefit of measuring how much fat we have?  Well once we know someone’s body fat percentage, we can use this information to help formulate dietary and exercise recommendations, we can monitor changes in body growth, development and composition, we can set goals and we can identify risks dependant on whether fat mass is too high or too low.

There is a minimum amount of body fat that is required for our body to function.  For men it is estimated to be around 3 – 5 % and it is estimated for women to be around 7- 10%.  So if that’s minimal, what’s excessive?  Well a healthy body fat percentage is considered to be around 12% for men and 18% for women.  Anything above that may start becoming a health risk.

The amount of body fat you have not only has a direct affect on your health, but on your body composition as well.  The more you have, the bigger and softer you look.  The less you have, the leaner you look.  Below is a guideline as to what each body fat percentage may look like:


The most common ways to measure body fat percentage that you will come across are:

1. Callipers

This is when your body fat is pinched and measured then input into an equation that calculates which percentage of your body is fat mass and which is fat free mass.  This method is good if you wanted to know your body fat percentage for aesthetic reasons as the only fat measured is subcutaneous fat, and it’s a good tool to keep track of your progress.

However, when being measured this way, it is important to have the same person do your measurements each time as each person will pinch and measure slightly differently, resulting in skewed readings and an inaccuracy of progress.

2. Bod Pod

The Bod Pod is an Air Displacement Plethysmograph.  It measures body mass and volume and they find density by dividing Mass by Volume.  Once the overall density of the body is determined, the relative proportions of body fat and lean mass are calculated.  When using this method of measurement, it is important to ensure you are measured at the same time every month and under the same circumstances.

For example, make sure the same amount of time has passed since last eating and preferably eat the same type of food prior to measurement as well.  Make sure you are in the same stage of your menstrual cycle as this will affect the amount of water you are holding on to etc.  Also make sure the same amount of time has passed since you last exercised, as all of these factors will have an effect on the consistency and accuracy of the results.

3. Body Fat Scales

These use a technique called Bioelectrical Impedance Analysis, or BIA for short.  Simply put, they send a very small and completely harmless electrical current through the body, which passes through fat free tissue much more quickly than it does through fat or bone.  Ultimately, it determines your body density and then uses a formula to calculate body fat percentage based of this – similar to the Bod Pod.

What all of these methods have in common is that an equation is used to predict what your body fat percentage is likely to be, and they assume that everyone runs of the same equation.  Unfortunately there is no one equation that can accurately determine body fat percentage for the whole population.

There are individual variables within each person, and there are individual variables within each individual and no one equation can take all of these variables into consideration to determine body fat percentage exactly.  So if you are having your body fat percentage calculated regularly, don’t take the figure as gospel.  The human body isn’t a mathematical equation and it is more complex than a single defined measurement.  Even lab results need to be interpreted in comparison to each value and not as independent, stand alone values.

What information can you get from your body fat percentage?

However all goals need to be measureable in some way to ensure you are heading in the right direction with your progress.  A good coach will not only take some form of measurement – whether that be scale weight, body fat percentage or girth measurements, but will also interview you regularly on how you are feeling, how your health is progressing, and will make sure you are getting fitter and stronger in the process.

They will also ensure that your measurements are relevant to your goal.  If your goal is to sleep better, that should be your main measure.  If your goal is to be able to run 5km, then fitness should be your main measure but if your goal is to look good naked, that’s when body fat percentage can be a good measure.

But remember – don’t let this number define you and don’t take this number as an accurate measure of where you are.  If you’re looking good and feeling good, performing well and are happy, then that means more than any calculated equation ever could.

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