They don’t tell you this as you’re starting out on your fitness journey, but your scale number is probably the most useless measurement you could be taking. Your weight changes every day depending on your hydration, what you eat, and whether you got enough sleep. Body fat doesn’t change like that.
Knowing how to calculate your body fat will give you an accurate measurement to base yourself on. No longer simply a guess, but rather a precise measurement of how much of your body is composed of fat cells versus muscle tissue, bones, internal organs, etc.
Why Body Fat Percentage Beats the Scale Every Time
Consider this situation, which happens all the time. A person follows a good diet, works out five days a week for two months, and sheds 4 pounds. Frustrated, the individual doesn’t understand why. Little do they realize that they lost 8 pounds of body fat and gained 4 pounds of muscle mass.
Their Body Fat Percentage would have told the real story. And getting their BFP isn’t something that requires fancy technology costing hundreds of dollars.
The Most Reliable Way to Calculate Body Fat at Home
What works best in practical terms is the formula for body measurement developed by the U.S. Navy using circumference. It has been around for many years; all that is needed is a tape measure, and the results will be within 3-4% accuracy compared to the clinical formula. This is sufficient for most home users.
Measurements needed:
For men – height, circumference of neck, just under Adam’s apple, and circumference of the waist, measured at the navel. For women – in addition to above mentioned measurements – also measure the circumference of the hips.
How to Calculate Your Body Fat Percentage Step by Step
So let’s go through an example to see how this really plays out.
If we have a male who is 33 years old, 5 feet, 9 inches tall, with a neck measurement of 15 inches and a waist size of 36 inches, he will be about 21% body fat according to this equation. He is well within the average fitness category.
Another person can be a 29-year-old female, who is 5 feet, 5 inches tall, with a neck measurement of 13.5 inches, 28-inch waist and 37-inch hips. This will place her at about 23% body fat, placing her in the healthy fitness category.
For men, this equation looks like this:
% Body Fat = 86.010 x log10(waist – neck) – 70.041 x log10(height) + 36.76
You don’t need to memorize that. Just use a body fat calculator and enter your measurements. But knowing the formula helps you understand why the waist and neck measurements carry so much weight in the result.
How to Take Accurate Measurements (Most People Do This Wrong)
Did you ever notice that your numbers seem to change week after week despite no changes in your routine? Chances are you have made a measurement mistake.
Waist: place the tape on your belly button level, not at the level where you wear your pants. Take a deep breath and exhale; don’t make any special efforts to contract or suck in your stomach.
Neck: measure right under the larynx, angling the tape slightly downward from its horizontal position.
Women’s Hips: measure around the widest part of the gluteal and hip area.
Do all measurements right after you wake up, before having anything to eat or drink.
What the Numbers Actually Mean
After you’ve learned how to figure out your body fat percentage, you have to learn what to do with the information.
Here’s a general guideline for men. Less than 6 percent is the essential fat, which is what competitive bodybuilders have for short periods of time prior to competitions. 6 to 17 percent body fat is an athletic body fat range. 18 to 24 percent is a typical fit person’s range. Anything higher than 25 percent can be potentially unhealthy after a while.
Due to the presence of more estrogen and their biological functions, women have more fat naturally. The essential fat in them is somewhere in the 10 to 13 percent range. 14 to 20 percent fall into the athletic category. Healthy fit range goes from 21 to 24 percent, and anything above 32 percent is unhealthy.
There is something important that needs to be pointed out. The ranges aren’t definite; there’s always a difference between active women and couch potatoes.
Other Ways to Calculate Body Fat Percentage
There are also other ways to measure body fat besides the Navy method. Let us consider what each method involves.
BMI is frequently mentioned as a tool to measure body fat; however, it is not really useful for that purpose as it completely ignores the amount of muscle in one’s body. Even a professional athlete might end up in the “obese” category. This measurement is best used as an initial rough approximation only.
Bioelectrical impedance scales use an electric current passed through your body to measure body fat, which depends on the level of resistance to it. Convenient to use, yet hydration significantly affects the results; drinking just one additional liter of water can alter the result by 2 to 3 points.
Skinfold calipers should provide accurate results when used properly. However, self-measurement with those can be problematic due to angle variance and lack of experience on your part.
DEXA scanning produces extremely precise results, including the body composition in various areas of the body. Though rather expensive ($50-$150 per test), it can serve as a once-a-year measurement.
How Often Should You Measure?
Every 4-6 weeks is optimal. Do it too often and the natural variations are going to frustrate you. Too rarely and you miss out on the feedback you need to stay on course.
Maintain a journal. Date, weight, and measure the circumference. In a few weeks, it will be obvious that a reduction in body fat percentage by 2-3 points shows up in those numbers despite hardly changing the weight.
And that’s the reason why you need to learn calculating your body fat percentage instead of using scales only. Numbers become much more accurate. With accuracy comes integrity, which simplifies decision-making.
