What is the best way to measure body fat?

There are many methods for testing body fat percentage. The most common and most accessible options are skin-fold testing and bioelectrical impedance. There are two other methods that are highly accurate but less accessible for the general public. Hydrostatic weighing, or underwater weighing, and DEXA scan which uses low dose x-rays to measure bone density, are often considered the gold standard for body fat assessment. Many colleges, universities, and professional sports teams have one or both of these systems. All of these methods can be accurate within 2-5% if done correctly.

Each of the following methods will give you an estimate of your body fat percentage. The margins of error range from 2 percent to 6 percent. However, even if your chosen method is not the most accurate, you can still benefit from taking consistent measurements, because you will be able to compare the results over time to see if your numbers are decreasing.

  • Hydrostatic -- or underwater -- weighing measures your weight in water as a way to determine your body's density. Your weight and the level of the water are recorded before and during submersion. It is considered one of the most accurate of all the body composition measures, but it is more expensive, more complicated, and more time consuming than other methods. Air-displacement plethysmography, or the Bod Pod, uses air displacement to measure body fat and lean muscle mass. This method calculates body volume by monitoring pressure changes in a closed chamber (plethysmograph). This data, together with body weight, is then used to estimate body fat percentage. Studies have found this to be a reliable technique that can quickly and safely evaluate body composition in a wide range of subject types. It is a relatively new technique that is becoming more widely available.
  • Dual-Energy X-Ray Absorptiometry (DEXA) also has been shown to have a high degree of accuracy. A machine passes over your body and takes measurements of your bone mass and soft tissue mass by sending a thin, invisible beam of low-dose x-rays through your bones.
  • Bioelectric impedance measures the body's resistance to electrical flow. The more body fat there is, the slower the electrical current will be. This method is based on the principle that lean tissue conducts an electrical impulse better than fatty tissue because fat contains almost no water. Water is a good conductor of electricity, whereas muscle is about 70 percent water. Bathroom scales that use this technology to measure body fat composition are commercially available. However, early reports suggest that these consumer products are fairly unreliable.
  • Anthropometry, or the skin fold test, measures fat by gently pinching several sites on the body (three to seven test sites are common) with calipers. The measurements are put into a formula that adjusts for factors such as gender, weight, and age. Although this is not the most accurate, it is the most readily available method for measuring body fat and is used most often at gyms and health clubs.

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    Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.