How to Calculate Body Fat
Which Body Fat Calculators Are Best
There are three main ways to calculate
- Home Body Fat Scales
- Skinfold Calipers (Callipers)
- Hydrostatic Weighing
Each of these body fat calculation methods
has advantages and disadvantages.
Using Home Body Fat Scales to Measure
Body fat scales claim to measure body fat
quickly and conveniently. These body fat scales use the Bioelectrical
Impedance method to measure your body fat percentage. A low-level electrical
current is passed through your body and the "impedance", or
opposition to the flow of current, is measured. The result is used in
conjunction with your weight and other factors to determine your body
fat percentage. Unfortunately, your body's "impedance level"
can be altered by many factors besides body fat. For instance, the amount
of water in your body, your skin temperature and recent physical activity
can all adversely affect the results.So only by following strict rules
can you hope to get an accurate measurement of your body fat using these
scales. The most important rules to observe in order to make a more accurate
calculation of your body fat are:
- Don't eat or drink for 4 hours before
the body fat measurement test.
- Don't exercise for 12 hours before the
- Some studies have shown variances as
high as 8 percent when using the bioelectrical impedance method even
if the rules are precisely followed.
- As with skinfold calipers (see below)
there are different equations used to calculate body fat from your body
density. These are usually pre-programmed into the machine.
- The best body fat scales tend to made
Using Skinfold Calipers (Callipers) to
Measure Body Fat Skinfold Measurements
Measuring body fat with a set of body fat
calipers is the most cost effective way to determine fat levels. But it's
important to use them correctly. For instance, either have a professional
take the measurements for you or buy a set of Accumeasure calipers (callipers)
and follow the measuring instructions. Accumeasure are the only calipers
than allow you to test yourself and most studies have shown that they
are very accurate.
Using Hydrostatic Weighing to Measure
Hydrostatic weighing (underwater weighing)
is the most accurate way to calculate body fat - that is, if you can find
a hydrostatic weighing tank.
How does hydrostatic weighing calculate
body fat? By using Archimedes Principle. Your examiner first calculates
your body density by measuring the amount of water you displace when you
immerse yourself in water. Then a formula is used to calculate body fat
based on your body density. The problem is finding a facility (University,
major gym or fitness center) which has a hydrostatic weighing tank!!
Table 1. Body Fat Guidelines from American
Council on Exercise
||Women (% Fat)
||Men (% Fat)
Why Body Fat Measurement is Important
Body fat is an important element in successful
weight control. Body fat requires fewer calories than muscle. So the less
fat/more muscle we have, the more calories we can eat before gaining weight.
Body fat is often expressed as our "Body Fat Percentage" or
"Body Fat Percent." Body fat percentage is the amount of body-fat-tissue
as a percentage of total body weight. If your total body weight is 160
pounds and you have 32 pounds of fat, your body fat percentage is 20 percent.
Body Fat Calculation and Health
The higher your percentage of fat above
average levels, the higher your health risk for weight-related illness,
like heart disease, high blood pressure, gallstones, type 2 diabetes,
osteoarthritis, and certain cancers. Also, the higher your percentage
of fat (and the smaller your percentage of muscle) the less calories you
need to maintain your weight and therefore the easier it is to gain weight.
This is because muscle is more metabolically active than fat tissue.
For a concise explanation of how ALL
surplus calories (from fats, protein AND carbs) are converted to body
fat and stored as adipose tissue, see How
We Gain Body Fat?