The Basics of how to measure bodyfat percentage

by Jennifer Collins, M.A.
(Albuquerque, NM, USA)

Essential fat is the minimal amount of fat necessary for normal physiological function. Essential fat values are typically considered to be 3% for men and 12% for women. Fat above the minimal amount is referred to as nonessential fat. It is generally accepted that a range of 10-22% for men and 18-27% for women is considered satisfactory for good health.

A body composition within the recommended range suggests you have less risk of developing obesity-related diseases such as diabetes, high blood pressure, and cancer. Having too low body fat can also cause health risks. Dropping below the minimal recommended levels of essential fat negatively affects the delivery of vitamins to the organs, the ability of the reproductive system to function, and overall well-being.

Body fat percentage charts are used to estimate the percentage of fat your body has based on certain factors such as skinfold measurements, circumference measurements, height and weight or water displacement.

Your body fat percentage is simply the percentage of fat your body contains. If you are 150 pounds and 10% fat, it means that your body consists of 15 pounds fat and 135 pounds lean body mass. Lean body mass, or lean body weight, refers to the total weight of organs, bones, and muscles. All tissues in the body, other than fat, are considered part of lean body weight.

Knowing your body fat percentage can help you set safe, realistic weight loss goals. For example: A woman weighing 150lbs wants to lose 30lbs. Her body fat percentage is estimated to be 25% as determined by using a 7 site skinfold caliper test. Multiplying her current weight by her percent fat determines her fat weight as 40lbs and her lean weight as 110lbs. At 120 pounds, this woman still requires 110lbs of lean body mass (bones, organs, etc.), but would only be carrying 10lbs, or 9% body fat. From the body fat percentage table listed, you can see that this is a dangerously low percentage of body fat for a female and she is most likely losing healthy lean weight as well.

When deciding to "lose weight" remember to consider that "weight" consists of both lean body mass and body fat. Use body fat percentage charts to keep your weight loss goals realistic - losing only fat and keeping healthy, metabolically active lean tissue.

Body composition can be estimated through various techniques. The following is a list of body composition assessment methods:
Skin Fold Caliper

The “skin fold” method measures your body fat percentage by pinching your fat with your fingers then measuring the thickness with a skinfold caliper. There are several formulas which predict body fat using skinfold caliper measurements. Formulas are created to be used with different populations from sedentary individuals to athletes. The SKYNDEX Skinfold calipers have the 3 most widely used formulas built into the calilpers. A 3-Site Jackson-Pollock formula for Athletes (http://www.skyndex.com/SKYNDEX-Jackson-Pollock-Skinfold-Caliper.html), 4-Site Durnin formula for the General Population (http://www.skyndex.com/SKYNDEX-Skinfold-Caliper-Durnin-Formula.html) and a 2-Site Slaughter-Lohman formula for children. Accuracy of the SKYNDEX Skinfold Caliper is discussed here (http://www.skyndex.com/resources/Skinfold-Caliper.html).

Bioimpedance Analysis

Bioimpedance (bioelectrical impedance) calculates your tissue and fluid compartments using an imperceptible electrical current. Lean tissue, which is over 70% water, is a good conductor of electrical current. Fatty tissue, which is low in water, is not.Thus, the resistance to the flow of electrical current measured by the analyzer can be used to calculate the body composition. Because the bioimpedance calculation is based on body water balance, your state of hydration can impact the level of accuracy. A very strict pre-test guildelines must be enforced to have accurate test-retest values.

Hydrostatic Weighing

Hydrostatic weighing is based upon Archimedes Principle which states that the buoyant force on a submerged object is equal to the weight of the fluid that is displaced by the object.This principle determines a person's percentage of body fat because the density of fat mass and fat-free mass are constant. Lean tissue, such as bone and muscle, are more dense than water, and fat tissue is less dense than water. Basically, muscle sinks and fat floats. Therefore, a person with more body fat will weigh less underwater and be more buoyant. Someone with more muscle will weigh more underwater.This method is considered the “Gold Standard” (+/- 1.5% error) of body fat measurement although new methods are being created with technology that may make hydrostatic weighing obsolete. Accuracy of the reading is contingent upon expelling all the air out of the lungs before weighing. Hydrostatic weighing requires expensive, specialized equipment.