Doctors, coaches and trainers like to use skinfold measurements to determine your body fat, but understanding the results can be a bit difficult for the average person. How can a bunch of pinched skin translate into an overall picture of body fat? The answer is a bit complicated, and it does involve a little bit of math. By taking accurate pinches of skin and plugging them into a formula, you truly can get an idea of the amount of fat in your body. How accurate those results are depends on how much you weigh, and how closely you followed directions when you took your measurements.
In the past, people determined your fat composition by performing complicated and expensive tests. In the late 1970's, researchers began to look for methods that were less expensive and easier for the average person to perform. Using skinfold measurements as a screening tool was an obvious choice. The small tool needed to pinch and measure skin, known as a set of calipers, is inexpensive and small. It's easy for a gym or a doctor's office to invest in this tool. Using calipers is also relatively easy, once you have a bit of practice.
In a skinfold test, you're asked to strip down to basic underwear. Then, the tester takes a measurement on specific parts of your body. Women are tested on the back of the arm, above the hipbone and the middle of the thigh. Men are tested on the chest, the tummy and the thigh. For each measurement, the tester pinches the skin, carefully avoiding the muscles below, and holds the pinch for 4 seconds. Then, the tester applies the calipers and writes down the measurements. In another method, the tester takes measurements in seven locations instead of three, though sticking to the short version is a good idea if you're new to caliper testing.
The caliper is measuring thickness, not body fat percentages, so those caliper measurements must be plugged into a calculator in order to get a final result. The math can get quite complicated and difficult to understand, but thankfully, many websites will convert your numbers for you and help you skip the math. One converter is located here: http://www.linear-software.com/online.html.
When the skinfold test was developed, the researchers made specific and clear instructions about where each measurement should be taken. Just getting close to the area is often not enough to allow you to get an accurate result. For example, the abdominal skinfold measurement must be taken with the skin pinched horizontally and not vertically, and the pinch must be 1 inch away from and 0.5 inch below the belly button. In order to truly understand where to take each measurement, it's wise to watch an expert perform the test at least twice. Then, you'll see how the test is done properly. Online descriptions can be confusing, but watching someone in person could help you understand the process a bit better. Additionally, people who are very obese or very thin might not benefit from this test. You won't be able to pinch enough tissue, or you may get too much to measure. These people should consider other forms of testing instead.