How Do You Measure Body Fat

Standards of Body Fat

Body Fat

Body composition is a better indicator of your health and fitness status than body weight, but it is still not perfect. Your genes determine your body type. Some body types carry more fat than others--no matter what you eat or how much you exercise. Percent body fat does not necessarily tell you how healthy or fit you are, or tell you how you look. There are large-framed students who have a higher percentage of body fat who train for triathlons and eat a healthy balanced diet. Other students may be thin and have a lower percentage of body fat, but don’t consume adequate calories or nutrients, lack physical endurance and strength, and don’t look healthy or fit. Unlike BMI, there is no one universally accepted set of body fat standards. As a result, you may see many different reference ranges from various fitness organizations, fitness magazines, and gyms. Not all of these reference ranges are based on research or take into account such things as genetics. As a result, many ranges are too narrow to reflect the diversity of healthy and fit bodies. A normal and healthy percentage of body fat varies substantially, and charts and graphs should not be regarded as the “end-all-be-all” of what is healthy and normal for you personally.

Body Fat Standards

The American College of Sport’s Medicine developed the following reference ranges based on research.

“Health standards” reflect the percent of body fat that generally does not increase your risk for health problems. Excessive body fat, especially around the abdomen, can increase your risk for high blood pressure, diabetes, osteoarthritis, and heart disease.“Fitness standards” reflect the percent of body fat that generally results from greater physical training. A greater percentage of muscle and lower percentage of fat may improve strength, speed, endurance, and agility. However, dropping below 16% body fat for women and 5% body fat for men DOES NOT further increase your athletic performance or level of fitness. Instead, too low body fat can actually impair your physical health and performance. Men and women need a certain amount of body fat to insulate vital organs, regulate body temperature, and ensure adequate production of sex hormones. In particular, women who restrict calories and exercise excessively may have a very low percentage of body fat and consequently have very low estrogen levels and stop menstruating. Because estrogen keeps women’s bones strong, women who stop menstruating are at much greater risk for stress fractures and a debilitating bone-thinning disease called osteoporosis.

How do you measure body fat?

There are many methods for determining body composition, including skin fold measures, bioelectrical impedance, Dual Energy X-ray Absorptiometry (DEXA), Bod Pod (air displacement) and underwater weighing.

Which method is best? The accuracy of each method can be highly variable depending on the skill of the person doing the measurement, whether the person being measured is well hydrated or dehydrated, how good the equipment is, and/or the reference tables used. Most techniques have an error of at least 3%, plus or minus. That means that if your body fat is tested at 20%, it could really be anywhere between 17 and 23%. You can get one reading today and a different one tomorrow. DEXA tends to be the most accurate, but is also the most expensive.

To accurately monitor changes in body fat over time, be sure to use the same technique with the same person under the same conditions each time you take a measurement. If you switch to a different technique, you may get different results for any number of reasons having nothing to do with real changes in your body composition. It takes several months to see any true changes in body composition, so there’s no need to repeat testing more than once every 6 months.