The Basics of Body Fat Percentage

What is Body Fat Percentage?


Body fat percentage (BFP or BF%)- also written as percentage body fat (PBF) - is the proportion of a body's fat mass in relation to total body mass. The percentage of body fat is useful for quantifying a person's body fat mass relative to their size and requirements.

Consider the fact that a 100kg male is going to have more fat mass than a 60kg male, even if both have the same body fat percentage. When comparing people to norms or other individuals, a relative measurement is required.


Calculation: (Total fat mass (kg)/Total body mass (kg)) x 100 = BF%


Example: a 100kg male with 20kg of body fat mass has a 20% body fat

Body fat percentage is a useful measurement of body composition and covers some of the limitations of Body Mass Index (BMI). BMI relies only on height and weight, and it cannot take into account the composition of the body. As a result, people with large amounts of muscle mass or shorter height can fall into the overweight/obesity category, despite being of healthy body fat percentages.


BMI Calculation: weight (kg)/height^2 (m) = BMI


Example: I am a 186cm, 94kg male, and around 10-12% body fat (measured via BIA). Despite a healthy body fat percentage, my BMI is 27 which put me in the overweight category. 

Measuring body fat percentage in addition to BMI is the best way to assess someone's body composition. Previously, body fat mass was hard to measure, which lead to a reliance on BMI. The current availability of body fat measurement tools is shifting the use of BMI to a first-step measurment, taken before body fat assessment. 


Measuring Body Fat Percentage


Measuring total body mass (body weight) is simple, but measuring body fat mass is more complicated and requires equipment. Bioelectric impedance (BIA) and dual energy x-ray absorptiometry (DEXA) are two measurements that are practical, non-invasive, accurate and reliable. 

Calipers can be used to measure skinfolds at key sites, which can then be extrapolated to estimate body fat percentage. However, the accuracy and consistency of measurement, and the inability to assess internal body fat, sees other techniques prioritised over calipers.


What is a Healthy Body Fat Percentage?

Females have greater essential body requirements than men, as demonstrated in the chart below. This is somewhat due to internal fat around reproductive organs. For this reason, women will see the abdominal muscles at a higher body fat percentage than men will (ie. 15-18% for females v 9-12% for men). 

At the other end of the chart, body fat percentages to be classed overweight and then obese are reasonably similar between both genders. A body fat percentage greater than 30% tends to be excessive for an individual's needs. An average body fat percentage is in the low-mid 20's (males) and mid-high 20's (females).


Body Fat Percentage Guide

To be used as a guide only.

Lowering Body Fat Percentage Without Losing Fat Mass


Recall that body fat percentage is a measure of total fat mass/total body weight, not a measure of total fat mass. That leaves it subject to potential manipulation. If you maintain body fat mass and increase total body mass, there will be a decrease in body fat percentage, despite no change in body fat mass.

Let me explain:
- A 65kg female at 25% body fat has 15kg of body fat mass.
- If she was to add 2kg of water to her body weight (now 67kg), while maintaining body fat mass (15kg) her body fat percentage will decrease from 25% to 24.2%.

Whilst this is not a massive change, it is significant - and perfect if you want to lose 0.8% of total body fat without having to diet or exercise!


Manipulation of Body Fat Percentage

This rule shows why gaining muscle mass can be vital for improving a physique and body fat percentage. If muscle mass is added, the percentage BF decreases. However, if muscle can be added and fat is lost, there is an even greater decrease in body fat percentage.

This does leave BF% up for manipulation. Over-hydration can lead to an increase body mass without increasing fat mass, leading to a decreased body fat percentage. 

When you see claims of 6kg lean mass (notice: not 'muscle mass') and a 5% loss in body in only ten days, you can be sure some form of manipulation (or straight lying) is in play.

Body Recomposition: Decreasing Your Body Fat Percentage


Gaining Muscle Decreases Body Fat Percentage (A Little)

A well-structured resistance training program combined with a diet containing sufficient protein intake can lead to increased muscle mass and decreased body fat mass, particularly in general population clients with minimal training experience. These combine to create dramatic decreases in body fat percentage along with physical transformations.

Strategies for building muscle mass are outlined in our client case studies (bottom of page) and the article below.

Article: Nutrition for Body Recomposition: Maintaining & Building Muscle


The Big Changes Come From Loss of Fat

While increase muscle mass alone will decrease body fat percentage to somewhat, it is the combination with decrease fat mass that provided the body recomposition goals that most people are seeking.

Decreasing fat mass need the be the main focus of the program to see large decreases in body fat percentage. To demonstrate this, consider the potential alterations in muscle mass of fat mass.
- Muscle Mass: 1-3 kg gained would be a good result for a 12-week training program.
- Body Fat Mass: 8-16kg lost would be a good result for a 12-week training program (depending on starting body weight).

As you can see, there is significantly more potential to decrease body fat mass by decreasing. By priotising fat loss in a body recomposition program, the trainee will see a more significant decrease in body fat percentage than if they were to prioritise muscle gain.

Strategies for fat loss are outlined in our client case studies (bottom of page) and the article below.

Article: Training for Body Recomposition: Fat Loss

Putting It All Together


Body fat percentage is a measure of the total body fat mass relative to total body mass and is a useful indicator of body composition.

Increasing muscle and water mass inside the body can decrease body fat percentage to a small degree, without the loss of any fat mass. However, it is the decrease of total fat mass that will drive significant decreases in body fat percentage. 

Creating and maintaining a 10-25% energy deficit will lead to the best results. I have run through numerous strategies to do so on this website before, so I won't do it again. We have put together several case studies outlining the systems we use with different clients. You can finds to them below.

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