What is body composition and how to change it.

First, let’s talk logistics. It’s impossible to have zero percent body fat. You wouldn’t be able to survive, because our bodies do need some fat. Essential fat is the minimal amount of fat that’s necessary for your body to be able to function properly. Now, that isn’t exactly an excuse for putting on a few extra winter pounds. The amount of essential fat you need is actually surprisingly low. According to the American College of Sports Medicine, the minimum amount for females is considered to be roughly 12%, and only 3% for males. If you’re wondering why females get the lucky (or unlucky, depending on how you look at it) break of having more fat, it has to do with what that fat is needed for. Essential fat is used for several purposes, including nutrient delivery, organ function, overall well-being, and (the one that sets females apart), reproductive function.

What is “healthy?”

The American Council on Exercise breaks body fat percentage into five general classifications. Essential Fat, Athletes, Fitness, Average, and Obese, in that order. For a female to fit into generally accepted “healthy” categories (athlete, fitness, or average) you would need to maintain between 14-31% body fat. For a male to fit into these same categories, you would need to maintain between 6-24%. Not quite falling in those categories? Keep in mind that everybody is different, and these are just considered guidelines. Even between different governing bodies, there are discrepancies, since ACSM considers 20-32% for women and 10-22% for men a healthy range. That being said, you will have a hard time convincing a fitness professional that 40% body fat may be within your ideal range. The numbers don’t fluctuate quite that much.

How do I know my body fat percentage?

Your bathroom scale definitely won’t tell you, so stop jumping on it every morning. You can estimate your body fat percentage a number of ways including skinfold measurements, water displacement, bioelectrical impedance analysis, air displacement, and DEXA scanning. Keep in mind that all of these estimations come with some margin of error. User error, hydration, algorithms and other factors affect the estimation, and none of them are 100% foolproof. Most measurements can estimate within a 3-4% margin (with DEXA and water displacement leading the pack in accuracy).

Now what?

So you know your body fat percentage. What’s next? Now, you can figure out what your healthy goal is, and what that means in numbers that you can see daily. Because let’s face it—body fat percentage estimations are not simple. Filling in the following equation will help you.

Current BF% ÷100= Decimal Form BF%

Current Weight x Decimal Form BF% = Non-lean Body Weight

Current Weight Non-lean Body Weight = Lean Body Weight*

Lean Body Weight ÷(1Decimal Form Desired BF%) = Total Body Weight Goal

*Your lean body weight is everything but the fat, including organs, bones, blood, muscle, etc.


Okay, so now that I have thoroughly confused you with all the algebra, let’s apply it to real life. Anything bolded in our equations are just that: the equation. Everything else will be your own numbers. Let’s look at an example:

Oliver is a little overweight, and is ready to get a fresh start. He currently weighs 200 pounds and his body fat percent is 30%.

30% Body Fat ÷ 100 = .30 Body Fat

200 pounds x .30 Body Fat = 60 pounds Non-lean Body Weight (or Fat Mass)

200 pounds 60 pounds Fat Mass = 140 pounds Lean Body Weight

So, based on our math, he has 140 pounds of lean body weight and 60 pounds of fat.

He’s hoping to get into a healthy body fat range and would like to get down to 20% body fat. This is his desired body fat percent. Enter this into the equation in decimal form.

Desired BF% ÷ 100 = Decimal Form BF%

20 ÷ 100 = .20 Desired Body Fat

140 pounds Lean Body Weight÷ (1− .20 Desired Body Fat) = 175 pounds

So Oliver would need to lose 25 pounds of fat to reach his goal of  20% body fat. His goal weight, if all of his weight loss came only from fat, would be 175 pounds.

What’s next?

Now that you know your current body fat percentage and you have a healthy goal with a simple, measurable number to track, it’s time to get to work. In our example, merely losing 25 pounds won’t put Oliver at the body fat percentage he wants. Without proper exercise and eating, about 25% of each pound will come from muscle rather than fat, disrupting our equation. But what if he would like to remain 200 pounds? That would mean he would need to build muscle as he loses body fat. While weight loss can occur with a calorie deficit, putting on muscle is not quite as simple and varies between each individual.

I wish there was a clear outline to provide body recomposition. Do A, B, and C, and you’ll have the body of your dreams. Unfortunately, each individual is unique so that kind of plan simply doesn’t exist. If it did, then everyone would already have perfectly chiseled abs, sculpted legs, bulging shoulders, and I would be out of a job.

While I don’t know what A, B, and C, are I can set you on the right path. I won’t label these A,B, and C, because I can’t promise you a dream body, but I will give you my top three tips to move toward your body recomposition goals.

Start here!

  • Try High Intensity Interval Training. HIIT has shown to increase post-workout calorie burn, giving you more bang for your buck.
  • Incorporate resistance training. Weight loss is not always going to come from fat, especially if you’re not working to build and preserve muscle. Muscle, or lean body mass, actually increases your base metabolic rate (the calories your body burns just by being alive), so if you lose weight from the wrong sources, you could actually slow your progress down!
  • Eat a healthy diet high in fiber and protein, and low in unhealthy fats and added sugars.


It is not going to happen overnight. Just like weight loss happens gradually, so does recomposition. If you stay consistent and keep working hard, the results will come.

Emily Wiley

iFit Trainer