Body Fat Testing - What's Your Body Fat Percentage?
it comes to tracking weight loss, most of us rely on the scale to
tell us whether we've lost or gained weight. But, as people are
fast learning, this isn't the best way to keep track of your weight.
A scale measures everything including muscle, fat, bones, and what
you ate or drank that day. It doesn't tell you what you really need
to know: how much fat do you have?
Body composition is simply the ratio of lean body mass to fat body
mass. Too much fat can lead to health problems like heart disease,
diabetes, high cholesterol and other serious conditions. If you
keep your body fat within a reasonable level, you'll be healthier
and, of course, slimmer.
For women, an acceptable percentage is between 25 - 31%.
How to Test Your Body Fat
DEXA (dual energy X-ray absorptiometry)
This test is used to measure bone density, but it also measures
body fat percentage as well as where most of your fat is (as if
you didn't know). The facts about DEXA:
- DEXA uses a whole body scanner and two different low-dose x-rays
to read bone mass and soft tissue mass.
takes about 10-20 minutes to do a body scan
- It provides a high degree of precision with a 2-3 % margin of
- This is considered a gold standard for measuring body fat and
- It's painless
Check with your doctor to see if this is right for you and call
your insurance company as they may cover it. The cost is usually
This is just a fancy way of saying underwater weighing. Like
DEXA, this test is one of the more accurate ones. How it works:
- You sit on a scale inside a tank of water and blow out as much
air as you can
are dunked underwater, where you blow out even more air
- Since fat is lighter than water, the more fat you have, the
more you'll float. The scale measures underwater weight to figure
out body density.
- The margin of error is around 2-3%, but the accuracy depends
on the amount of air you expel. You have to blow it ALL out or
it won't be as accurate.
- This is a difficult way to measure body fat since it can be
uncomfortable and even scary to be dunked underwater with no air
in the old lungs.
Many universities offer this test for around $25-$50. Call your
local university and ask if they offer this. Fitness Wave offers
mobile hydrostatic weighing in Southern California, Nevada and Arizona
Calipers (aka, the Pinch Test)
This method uses calipers to measure skinfold thickness at several
areas of your body. How it works:
expert pinches your skin at different areas and measures them
- The results are plugged into a formula to determine your body
- The result is based on the idea that thickness of fat under
the skin reflects total body fat.
- It CAN be as accurate as the methods mentioned about, but usually
isn't. It depends on the skill of the tester at separating your
fat from your muscle and finding the right spots to pinch.
- The results can also be skewed if you're older (since fat moves
inward with age) or if you are nonwhite, since formulas are based
on white subjects.
- This is one of the more accessible ways to check body fat and
is generally painless.
You can get tested at most health clubs and universities for little
or no cost. You can also buy your own calipers, but I wouldn't get
too excited about the results you get. If you're not skilled at
it, the results can be way off.Always make sure you get the same
person to test your body fat since results can vary from tester
This is one of the quickest methods of testing body fat using a
using a handheld scale or standing on a BIA scale, a signal passes
either from hand to hand or foot to foot.
- The faster the signal travels, the more muscle you have.
- The results are based on the fact that water conducts electricity.
Fat contains almost no water while muscle is about 70% water.
- This method CAN be accurate (4% margin of error) but the results
are affected by hydration, food intake and skin temperature. If
you're dehydrated, you're body fat percentage will read higher
than it is.
This is an easy way to test your body fat. Be sure you test at
the same time of day, preferably first thing in the morning before
breakfast, but after a glass of water.
Body Mass Index
You can figure out your Body Mass Index using a formula or with
an online calculator.
- BMI takes into account your weight and height, giving you a
number that you compare with a BMI chart.
- It doesn't give you a body fat percentage, but indicates whether
you're obese or overweight. For example, if your BMI is 22, that
doesn't mean your body fat is 22%.
- A BMI less than 18.5 indicates underweight
- A BMI of 25 - 30 is considered overweight
- A BMI of over 30 is considered obese
- This calculation isn't as accurate, as it doesn't take into
account age or sex. A muscular person may have a high BMI that
doesn't reflect actual body composition
Obviously, there are many methods to test your body fat (and many
we didn't have time to talk about). Accuracy is important, but all
of these methods (if used correctly) can measure body fat within
2-5%. Tracking your body fat is the best way to make sure that you're
losing fat and gaining muscle. Just don't test it too often since
body fat measurements don't show small changes. Every 4-8 weeks