I have been measuring body fat levels on professional athletes for the last 25 years. Ironically, the purpose is not to determine how much fat they have; rather, it’s to identify their ideal playing weight. Regardless of the sport, every professional athlete has only one goal – ­peak performance. Training a professional cyclist is similar to designing the perfect race car. The point is to have the biggest engine and carry the least amount of excess weight. The NBA player wants to maintain as much muscle mass as possible, until the point where it begins to decrease his vertical jump or first-step quickness.

The main reason I measure body fat levels on athletes is to quantify fat pounds and muscle mass as separate components. The ability to separate these two variables helps fine-tune training programs that impact fat levels and lean body mass. Determining an athlete’s ideal playing weight only requires a simple calculation of adding the two variables together.

Identifying an “ideal playing weight” for an athlete is relevant, but different, than a “healthy living weight” for an individual interested in maintaining general good health.

The connection between being “overweight” and the increased risk of developing certain diseases began back in the 1950’s. Although the evidence of this connection continues to be highly debated, the overall consensus is that there is a negative health risk with being “overfat,” not necessarily being “overweight.” To date, the list of medical conditions shown to be associated with “overfatness” includes high blood pressure, high cholesterol, Type 2 diabetes, sleep apnea, osteoarthritis, and certain cancers. The key finding is that there are individual differences in the relationship between a person’s medical risk and levels of excess body fat.

My recommendation to individuals whose main goal is to stay healthy is to consider measuring their body fat in a similar manner as the professional athlete, but with a different perspective in mind. While an athlete wants to maximize performance by achieving the lowest fat levels possible, the typical adult should view body fat measuring as a tool that helps minimize the risk of developing lifestyle related diseases.

For example, an individual may be diagnosed with high blood pressure and have a body fat percentage of 30%. This person begins a structured exercise program and changes his caloric intake. A few months later the individual remeasures his blood pressure and percent body fat levels. As expected, both blood pressure and body fat percentage drops. The blood pressure measurement may now be in the healthy range, but the body fat percentage may still lie out of the healthy zone. In this case, the individual has to remember the goal was to reduce the risk of high blood pressure, not to have the lowest percent body fat. Many people mistakenly believe that continued fat loss always results in lowered blood pressure. In essence, the health conscious adult needs to define a “healthy living weight” in terms of health risks, medical conditions, and the effect of being “overfat.”

The only drawback with underwater weighing is its limited capability to break body composition into only two components: fat pounds and lean body mass. For example, a 200-pound male who is measured at 20% body fat via underwater weighing knows he has 40 pounds of fat and 160 pounds of fat free or lean tissue.   Today’s new technology has drastically improved, allowing lean tissue to be further separated into bone, skin and muscle weight. An additional advantage of the new technology is the ability to compare upper and lower body segments with regards to these variables. For example, a test can tell a person he has 75% of his fat in his legs, or that his right arm and left leg have significantly more muscle and bone density than the opposite limbs. Quite fascinating!

Other Methods of Body Fat Testing
Today there are many other methods available for estimating percent body fat. It is important to realize that no matter which procedure you use, all measurements can be slightly off. The degree of error pertains to the test’s validity or reliability. Validity refers to a test measuring what it’s actually supposed to measure. Reliability is the degree that a test measure is stable and consistent, produced by retesting. The following should help you compare the validity and reliability of today’s most common methods of measuring percent body fat.

Skinfold Measurements with Calipers

Commonly known as the “pinch test,” skinfold measurement testing is widely used to determine a person’s body composition. The test measures skinfold thickness at specific locations on the body. The tester literally pinches the skin at certain locations and pulls the skin away from the muscles so only skin and fat tissue are being measured. Formulas have been devised to calculate body composition based on the caliper measurements. 

ADVANTAGES: It can be 98% accurate and reliable when conducted by a skilled, trained tester. It is easily performed and fairly inexpensive. Scores are readily calculated by looking at a chart that shows age, gender, and the skinfold measurements.

DISADVANTAGES: Skinfold measurements are difficult to perform when a person has a high amount of body fat. Also, the test will not be valid or reliable if the tester is not skilled or the calipers are not calibrated.

Bioelectrical Impedance
This form of testing is popular, because the testing devices are relatively inexpensive and the test itself does not require a high level of proficiency to perform. The science behind this procedure involves the transmission of a low level current through the body. There are two ways to perform this test, either by placing electrodes on the ankle or the wrist or by standing on a specialized impedance scale. Both modalities are based on the premise that muscle’s high water content makes it very conductive. The basic theory is that the more body water that is present, the higher the amount of muscle per pound of weight. Unfortunately, most exercisers have a tremendous amount of fluctuation in their fluid levels due to sweat loss vs. fluid consumption. It is imperative – with respect to reliability – that pre and post-test settings pay particular attention to the subject’s exercise and fluid status prior to testing.

ADVANTAGES: Testing can done quickly, inexpensively and in the privacy of your own home.

DISADVANTAGES: It can have very poor reliability due to exercise and hydration states.

Circumference Measurements (girth measurements)
Circumference measurements are becoming more and more popular due to the fact that they do not require expensive equipment or a skilled technician. The science behind girth measurements is based on the fact that fat tends to accumulate around the midsection. Consequently, if your circumference measurements increase, you are increasing your body fat. In other words, you can now correlate “inches gained” to fat pounds gained and “inches lost” to fat pounds lost. The calculations to predict body fat percentage can be done using a hand held calculator or online by entering the measurements in inches.

ADVANTAGES: It is relatively accurate and very reliable when performed on populations who are average to above average body fat. The calculations can be easily performed.

DISADVANTAGES: It does not work well on males under 7% and females under 15% body fat.

Stay tuned for our next blog on the relationship between your genetics and body composition. You will learn how and when fat cells are created in our bodies, who is predisposed to be being over fat, and what you can do to maintain a healthy weight irrespective of your genetic profile.

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Are you intrigued by this article? Are you interested in learning more about your own genetic profile? Would you like to know how you can improve your health and fitness by knowing more about your genes? Email us: genetics@fitdigits.com.