BODY FAT

BODY FAT MEASUREMENT

Information: body fat issues. Body fat percentage is measured through different methods.

Some methods of estimating body fat are expensive, require special laboratory equipment, and are not readily available.

1. Skin-fold Callipers / Body Fat Calipers.

Body fat can be measured using simple skin-fold calipers. It is used to measure the amount of fat just under the skin at areas like: upper-arm, upper-back, lower-back, stomach and upper thigh.

These fat-measurements are then averaged and put into a formula to determine the total body fat percentage. It relies on as assumption that the thickness of the fat below the skin is proportional to the fat stored deeper in the body.

2. Bioelectrical Impedance (BI).

Bioelectrical impedance involves sending a small electrical signal through the body. The more muscle a person has, the more water their body is able to hold.

The greater amount of water in a person's body, the easier it is for the current to pass through, the more fat present in a person's body, more resistance is blocking the signal. Bioelectrical impedance can be quite accurate but the results are affected by intake of food, body temperature and water intake.

3. DEXA (Dual Energy X-ray Absorptiometry).

The DEXA machine measures bone density. However, it can also measure body fat percentage. It uses a body scanner and two low-dose x-rays to read bone mass and soft tissue mass.

From start to finish, it takes about 10-20 minutes to do a body scan. It offers a high degree of precision in measuring body fat percentage but the process is expensive.

4.Underwater Weighing.

The percent body fat is calculated on the basis of the density of the body. The density of the body is calculated by an equation that involves measuring a person suspended on a trapeze in the air and then weighing the person under water.

5. Body Mass Index.

Body Mass Index (BMI) is a relationship between weight and height that is associated with body fat and health risk. Weight is converted to kilograms; height is converted to meters and then squared. These numbers are then put into an equation to determine BMI: BMI = kg/m2.

6. Girth Measurement.

Girth measurements are circumference measurements taken at a specific body site and recorded. They are converted to a constant and then entered into a formula to predict percent body fat. The sites measured differ depending on a person's age and gender.

For ages 18 to 26: Men measure the right biceps, right forearm, and abdomen. Women measure the abdomen, right thigh and right forearm.

For ages 27 to 50: Men measure the hips (buttocks), abdomen, and right forearm Women measure the abdomen, right thigh, and right calf.

7. Near Infrared Interactance.

This method uses the principles of light absorption and reflection to measure body fat. The equipment used is a computerized spectrophotometer with a single, rapid scanning monochromator and fiber optic probe. The probe sends out electromagnetic radiation from the monochromator to the surface of the biceps of a person's dominant arm.

The signal penetrates the underlying tissue to a depth of one centimeter. Shifts in the wavelength of the reflected beam and a prediction equation are used to compute the percent body fat.

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