Understanding Body Fat Percentage and BMI

Many of us are in the dark when it comes to understanding what their body fat percentage means and what it should be. If your doctor told you that your body fat percentage is too high, do you understand what he’s talking about? Most people are confused by this and I’d like to clear up some of the confusion for you.

What is body fat percentage?

A body fat percentage is calculated by taking the total weight of a person’s fat and dividing it by the person’s overall weight. Every person needs some body fat in order to maintain hormonal functions and to allow the body to work effectively. Women need more body fat than men.

The percentage of fat NEEDED on a man is 2-5%, while a woman NEEDS at least 10-13%.
Body fat percentage is an accurate measurement of how much fat your body holds.

Description Women Men
Essential Fat 10-13% 2-5%
Athletes 14-20% 6-13%
Fitness 21-24% 14-17%
Average 25-31% 18-24%
Obese 32%+ 25%+

Body fat percentage Is different than BMI. Don’t get your body fat percentage confused with your BMI (body mass index).

What is BMI?
Body mass index is a measurement that can be used as a comparison of individuals of different heights in terms of their weight. BMI is calculated by dividing your weight (in kilograms) by your height (in meters, squared). A normal BMI is around 18.5 – 24.9.
Here’s a graph to show you how BMI is determined. Muscle mass is not considered in the equation.

BMI isn’t always an accurate measure of body fat because the individuals who have a lot of muscle on their body may weigh more, but the BMI doesn’t reflect that accurately.
For example, let’s say we have two men, Joe and Shmo.

Joe is a collegiate athlete who is in the weight room every day. He works as a personal trainer during the day and stays active in the evenings. He has a lot of muscle mass on his body. He weighs 215lbs.

Shmo is the same age, height and weight as Joe, however he chooses to be sedentary by having a desk job all day and plays video games all night.

Joe and Shmo may have the same height and weight, but their bodies will look completely different. Their BMI will be the same because it’s only calculated by height and weight, yet their body fat percentage will be very different!  They will look COMPLETELY different!

Here’s a great visual to show you how one body fat percentage could look completely different on two individuals due to muscle mass.

(Image Source)

In order to get your BMI, you can just read the above chart. In order to get your body fat tested, you may have to go to a gym or arrange an appointment to get it tested.
How to get your body fat percentage tested? I have listed below the most popular procedures for testing body fat.

Here is a great visual on how body fat percentages differ on males and females.

How To Test Body Fat


Underwater Weighing – This is the most accurate test. This is done by submerging a person in water and calculating the body fat based on the displaced water. This will give an actual measurement of body density rather than just a prediction.

Air Displacement Plethysmography (ADP) – Also known as a Bod Pod. This is a technique that uses air to measure body volume through air displacement. The person is put into a sealed chamber and air flow determines body fat and lean body mass. This technique is just as accurate as underwater testing.

Skinfold Tests – This is done through calipers. It is also known as a pinch test. Several areas of the body are measured with the caliper which produce an estimated amount of body fat. This isn’t the most accurate reading, however it can be useful if you consistently test using the same method. If you do the test exactly the same and your body composition changes, you’ll be able to see changes over a period of time.

You may also see some handheld devices at your local gym. These have proven to be the most inaccurate type of body fat testing.

The key to get an accurate reading is consistency. You can use any of the methods above as long as you’re consistent on how you test it and what method you use. If you use the calipers for skin folds every few weeks, you should be able to notice your body changing because you have measured the same way each time.

To better explain the differences that body fat percentages can have on someone, I’d like to show a few pictures of people who may have the same body weight, however their body fat percentage is completely different due to muscle mass.

If you’d like to get an accurate measurement of your body composition, I’d suggest you get your body fat percentage taken.

If you have any questions or comments, feel free to leave them below!

12 thoughts on “Understanding Body Fat Percentage and BMI”

  1. I was SO mad at my gym because they pretty much made me do the machine test thing for body fat. I didn’t want to do it in the first place, and then, they told me I could stand to lose a few percentage points. I reassured myself by saying they were inaccurate machines and I wouldn’t trust anything but the bod pod. :p

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  2. Hey Erin- aren’t those pictures from Leigh Peele or something like that? I know I’ve seen those around previously on other fitness sites. I’m genuinely not being catty, but if they came from some place else you should include their source and not write livelifeactive on them. Maybe I am wrong about where I’ve seen them though.

    I’d love a bod pod reading!

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