The Basics of Body Fat Percentage
What is Body Fat Percentage?
Body fat percentage (BFP/BF%/PBF) is the proportion of the body's fat mass relative to total body mass. It is a useful measurement for quantifying a person's body fat mass relative to their size or objectives.
Consider that a lean 100kg male will have more fat mass than a lean 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 useful for assessing 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 = weight (kg)/height (m)^2
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. However, the availability of non-intrusive body methods of assessing body fat, such as bioelectrical impedance assessment (BIA) and dual-energy x-ray absorptiometry (DEXA) has made this more accessible.
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.
Callipers 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, see other techniques prioritised over callipers.
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 (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 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 '20s (males) and mid-high '20s (females).
Lowering Body Fat Percentage Without Losing Fat Mass
Recall that body fat percentage is a measure of total fat mass divided by total body weight, not a measure of total fat mass on its own. 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!
Manipulating Body Fat Percentage
This rule shows why gaining muscle mass can improve physique and body fat percentage. If muscle mass is added, the percentage BF decreases. However, if the 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 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 fat in only ten days, you can be sure some form of manipulation (or straight lying) is in play.
Body Recomposition and 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.
The Big Changes Come From Loss of Fat
While increasing muscle mass alone will decrease body fat percentage somewhat, it is the combination with decreased 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 prioritising 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.
Body Recomposition Calculator
Try our body recomposition calculator to establish your goals before getting started
Body Fat Percentage FAQs
How many kilograms are in 1% body fat?
This depends on your body weight. To convert body fat percentage to kilograms, multiply the body fat percentage by total body weight.
If you weigh 80 kg and are 20% body fat, 20% of your body composition is body fat. Multiple total body weight (80 kg) by body fat percentage (20%), and you have the total amount of body fat in kilograms (16 kg).
How can I calculate my body fat percentage?
Estimating body fat percentage is very difficult. You can take a photo and compare it to reference photos of different body fat percentages, but this is an estimation at best. DEXA or BIA is a quick and accessible way to assess body fat percentage.
How do I calculate my target body fat percentage?
This is a good question. Many people have the goal of reaching 10% body fat and want to work out what they need to do to get there. It’s not as simple as taking it away.
Let’s say I weigh 100kg at 20% body fat (ie. have 20 kg of body fat mass), and I want to reach 10% body. You might be thinking ‘that’s easy’, just lose 10 kg of fat and body fat will be halved to 10%. However, if I lose 10kg of fat, then I also lose 10 kg of body weight, so now I have 10 kg of body fat and weigh 90kg, which equates to just over 11% body fat.
To hit 10% body fat, I need to drop 11kg of body fat, which will take bodyweight to 89kg. Even then, I’m just above 10% body fat (but close enough)
To help you out, I have embedded our Body Recomposition Calculator. Enter your current weight and body fat percentage to see the impact of gaining muscle and losing fat on your body composition.
Can you give me a training program to lose body fat and build muscle?
Our training programs at Integrated Fitness & Nutrition are tailored to our coaching clients’ goals, experiences and lifestyle. We do offer our self-directed Restart Program to help people prepare for coaching to ensure they get the most from it. If you’ve made it this far, use the code IFN20 to get 20% off the Restart Program today.
