Health and Fitness Information Center

Measuring Body Fat with Calipers

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Calipers (Anthropometry - Skinfold Measurements) - Using hand-held calipers that exert a standard pressure, the skinfold thickness is measured at various body locations (3-7 test sites are common). Then a calculation is used to derive a body fat percentage based on the sum of the measurements. Different prediction equations are needed for children and specific ethnic groups (over 3,500 equations have been validated).

This approach usually uses underwater weighing as a reference method. The caliper method is based upon the assumption that the thickness of the subcutaneous fat (found just under the skin) reflects a constant proportion of the total body fat (contained in the body cavities), and that the sites selected for measurement represent the average thickness of the subcutaneous fat.

Skinfold measurements are made by grasping the skin and underlying tissue, shaking it to exclude any muscle and pinching it between the jaws of the caliper. Duplicate readings are often made at each site to improve the accuracy and reproducibility of the measurements.

Often to save time in large population studies, a single skinfold site measurement is made to reduce the time involved. Such a test should be used only for a rough estimate of obesity.

Generally speaking, skinfold measurements are easy to do, inexpensive and the method is portable. Overall, results, can be very subjective as precision ultimately depends on the skill of the technician and the site measured. The quality of the calipers is also a factor; they should be accurately calibrated and have a constant specified pressure. Inexpensive models sold for home use are usually less accurate than those used by an accredited caliper technician. The more obese the subject, the more difficult to "pinch" the skinfold correctly, requiring even more skill to obtain an accurate measurement.