Body Composition Estimations: Bioelectrical Impedance Analysis & Waist-to-Hip Ratio

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  • 0:05 Body Composition
  • 1:45 Bioelectrical…
  • 3:44 Waist-To-Hip Ratio
  • 5:31 Lesson Summary
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Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Your body composition is the relative proportions of fat and lean tissue found on your body. Learn how body composition is evaluated using methods such as bioelectrical impedance analysis and the waist-to-hip ratio.

Body Composition

I'm sure you have heard that obesity is a growing problem around the world. In fact, most researchers say it has become an epidemic. But what exactly is so wrong with carrying around these extra pounds?

Well, as it turns out, having too much body fat creates problems from your toes on up. The excess weight stresses your joints and increases the risk of developing arthritis in your feet and knees. High amounts of fat have been linked to gynecological problems in women. We also see high body fat linked to conditions, such as type 2 diabetes, gallstones, asthma, heart disease and even depression. While some body fat is needed for the body to function properly, having too much moves you into the overweight category and affects your health.

Your body weight is the sum of the amount of fat on your body plus the amount of lean tissue you carry. Lean tissue consists of pretty much everything but fat, so your muscles, bones, organs and tissues are considered part of your lean body mass. We use the term body composition to refer to the relative proportions of body fat and lean tissue on a person's body. By measuring body composition, we can determine if a person is negatively affecting their health by carrying around too much body fat. In this lesson, we will take a look at two methods used to estimate body composition: bioelectrical impedance analysis and waist-to-hip ratio.

Bioelectrical Impedance Analysis

When it comes to body fat, men and women are not created equal. In general, women carry more fat than men. Women need this extra fat for reproductive reasons. Therefore, we see that women need to carry between 10 and 13 percent body fat for essential purposes. For a man, the essential range is between two and five percent.

Body composition can be measured using techniques like bioelectrical impedance analysis, or BIA, which is a method used to estimate a person's body fat percentage using a small electric current. This method is easy to perform and harmless. The analysis measures how easily the current moves through the tissues of your body. It involves electrodes attached to various parts of your body or a simple device that is either held in both hands or stood on with both feet. Does your bathroom scale analyze your body fat percentage? If it does, then it's using bioelectrical impedance. When you contact the device, you complete a circuit in which the electric current can flow.

The test is able to distinguish lean tissue from fat because the current will move more easily through your lean tissues. Lean tissues are high in water, which is easy to pass through, whereas fat slows, or impedes, the movement of the current. To keep this straight, think of swimming through a pool of water compared to swimming through a pool filled with fatty liquid, like vegetable oil. There would be more resistance in the oil pool.

While this test is quick and easy, the fact that it's based on the water content of your body can make it inaccurate. For instance, if you were working outside on a hot summer day, the sweat you lose could cause your body water level to be lower than normal. This would show up on a BIA test as a lower amount of lean tissue and record an artificially high body fat percentage.

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