Body fat is sometimes used as an estimate of how healthy or fit you are. Statistically, someone with a lower body fat than someone else is probably more fit. This is not always true, however. A person with an extremely fast metabolism who eats junk food all day long may maintain a low body fat, but make no mistake: they are less healthy than someone with a higher body fat who eats healthy foods and exercises. The body fat measurement provides a percentage of your body that is considered fat. It is based on equations that are fairly accurate, give or take a few percentage points. It is not the equations that are the problem, it's the method of measurement. There are many different ways to measure body fat. Operator error can make the measurement inaccurate and ruin any precision.

It is recommended that you measure your body fat consistently. Either perform the test yourself, or have someone else do the test. If you have different people perform the test, even trained professionals, the results may vary widely. The key with body fat is to remember that it is just another number - a statistic - to help you gauge your progress, it is not "the end all". Someone who looks great and feels good but has a higher body fat has no reason to drop any lower. Someone who appears to have extremely low body fat based on measurements but looks overweight and feels terrible should probably consider dropping weight. One specific percentage doesn't mean the same thing for everyone or even every age.

I explain more about body fat, how to achieve a major physique transformation, and my own story in "Become the Journey: A Transformation Guide."

I prefer the calipers over other methods for testing body fat, when your Body Mass Index indicates that you are not in the obese range. The majority of equations for body fat were not computed from obese or heavier people, and therefore they can be wildly inaccurate. A common mistake is for someone who is obese to assume they have a higher amount of muscle on their body due to an inaccurate body fat measurement. I use the scale as the primary tool until you are in the overweight range (but not obese) on BMI, and then start to use the calipers for body fat. While other methods, such as body fat scales and hand-held devices are useful for measuring trends, they tend not to be as accurate or consistent as calipers.

Whoever administers the test should test each site in round robin fashion at least twice. In other words, one pinch on your abdomen isn't enough. They should pinch your abdomen, then other areas, then return to the abdomen for a second pinch. If the results vary greatly, they should take additional measurements to narrow down the precision of the answer.

The percentage that you obtain is your body fat. Multiply your body fat by your weight to yield the total amount of fat that you are storing. The difference between your weight and the total amount of fat that you are storing is your "lean mass". Many people mistake this for muscle - it is not. It includes muscle, but also includes bone, tissue, water, organs, even the contents of your stomach after your last meal. Just because your "lean mass" goes down doesn't mean you lost muscle. You might have lost water. Just because your "lean mass" goes up doesn't mean you gained muscle. You might have started to retain water. Again, use only as a guide - in general, your body fat should decrease over time until it stabilizes at a level that you are comfortable with.

Instructions: there is a 3-site method and a 4-site method. Both methods are similar in accuracy. Pick whichever method you like, and key in the appropriate values.

For the 4-site method, the sites are the same for men and women: Abdomen, Suprailiac, Triceps, and Thigh.
For the 3-site method, use this guide:
Male 3-site: Chest, Abdomen, Thigh.
Female 3-site: Triceps, Abdomen, Suprailiac.

NOTE: When taking your actual measurements, you should stand relaxed with your arms hanging comfortably by your sides - do not flex! When taking the thigh measurement, keep both feet on the ground, but shift your weight to the leg that you are not measuring.