Many children are measured in school each year. Bodybuilders are obsessed with it. Magazine covers are devoted to the topic. What is it? Body fat. Most people only have a vague idea of what is a healthful level of body fat. Learning about different ways to measure body fat can help you keep track of your level of fitness and prevent a small problem from growing into a big one.
Body Fat and Body Composition
Body composition refers to the percentage of tissue that is fat vs. non-fat tissue and water. A measurement called the body mass index calculates mass and volume percentages. BMI is equal to height in centimeters divided by mass in kilograms. Doctors use the BMI to assess risk factors from obesity, but muscular, fit men will have a high BMI. Measuring body fat is better for determining whether a person is healthy or obese.
Water Displacement
The gold standard of body fat determination is a test in which a person is submerged in water while exhaling air out of his lungs. It is accurate to within 1 percent to 2 percent in determining body fat. The test is available at health centers and mobile facilities, but the cost is the same as a medical test and insurance might not cover it for a recreational athlete.
Calipers
A simple, inexpensive and noninvasive way to estimate body fat is by using calipers. Using pre-determined anatomical sites, calipers measure the fat underlying skin as it is pulled away from muscle. The skin fold measurements are added, and compared to a table listing body fat percentage in rows determined by age and sex. For example, a healthy fat percentage of 20 in a 22-year-old woman is considered "fit." A trained, experienced tester can measure body fat within 3 percent to 4 percent using calipers.
Circumference
Severely obese people and the elderly have loose skin, making accurate caliper measurements difficult. Some people might be shy and uncomfortable getting pinched with calipers. The military has tables of body fat percentages based on circumference measurements at different anatomical locations.
Bio-Impedence
Devices are available that estimate body fat by sending a weak electrical current through the body. Much like radar or sonar, the delay in the signal return registers an estimate of body fat. Scales, the Wii Fit game console, and dedicated body fat analyzers are all available. They are considered as accurate as using calipers, and can be used without assistance. This is a good option for people who wish to make measurements in private.
References
- Sarasota County: ACSM Body Composition For Men and Women
- "ACSM's Guidelines For Exercise Testing and Prescription, 6th Edition"; Lippincott Williams & Wilkins; 2000
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