Calculating Your Body Fat - How to Calculate Your Body Fat

Woman measuring body fat
Getty Images/David Madison

You may focus on the scale if you're trying to lose weight, but a much better measurement is your body composition or how much muscle you have as opposed to fat.

Your body fat percentage tells you much more than the scale does.  In fact, you can actually lose body fat while the scale may stay the same or even go up.  Don't mistake that for weight gain, but as progress.

Calculating Your Body Fat

There are a number of ways to calculate your body fat - You can use an online calculator, of course, which will only give you a broad estimate, or you can get serious and get the most accurate measurement, which comes from Hydrostatic Weighing.

Like everything else, there is a formula you can use to calculate your body fat.  This was published in the British Journal of Nutrition back in 1001 and is the basic standard we use for estimating body fat using your age and your BMI.

For men:

(1.20 x BMI) + (0.23 x age) – 10.8 – 5.4

Example:  A man who is 42 with a BMI of 30 would have a body fat percentage of about 29%, considered obese according to the chart below.

For women:

(1.20 x BMI) + (0.23 x age) – 5.4

Example:  A woman who is 45 with a BMI of would have a body fat percentage of about 31%, which is just in the acceptable range.

Keep in mind these are very broad approximations and these numbers can be off, so just use them as a basic guideline.

Body Fat Categories

10-12%2-4%Essential Fat

How to Reduce Your Body Fat

So what's the secret to burning fat?

  It's a simple equation - Burn more calories than you eat.  But actually making that happen takes a bit of work.

Your Diet

How much you eat is, of course, a huge factor in losing or gaining body weight.  You can always follow a popular diet, of course, but what experts already know is that diets generally don't work.

  What does work is making small changes like:

  • Reduce your portion sizes
  • Eat smaller meals more frequently throughout the day and avoid skipping breakfast.
  • Eat lots of fruits and vegetables to fill you up and give you the nutrients you need
  • Eat more fiber - Fiber fills you up so that you don't have room for naughtier foods
  • Avoid sugary foods and junk food (dug
  • Limit how much alcohol you drink

Your Cardio

Cardio is an important part of any fat loss program, but you want to make sure you do the right kind of cardio.  Make sure you're including some high-intensity interval training in your program, maybe 1-2 times a week.  You'll burn more calories and increase your afterburn.

Your Strength Training

We often focus on cardio for losing weight, but adding more muscle will really help you burn more fat.  Muscle is more metabolically active than fat so, the more you have, the more calories you burn all day long.  Just a couple times a week is all you need to add lean muscle tissue and burn more fat.


Deurenberg P1, Weststrate JA, Seidell JC. Body mass index as a measure of body fatness: age- and sex-specific prediction formulas. Br J Nutr. 1991 Mar;65(2):105-14.

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