Assessing Body Fat

Skinfold Measurements

Skinfold measurements are made with skinfold calipers. Some of the more accurate and expensive calipers are the Harpenden, the Lange, and the Lafayette calipers. Some of the less expensive calipers include the Slimguide, the Fat-O-Meter, and the Adipometer. Regardless of the type employed, it is important to use a consistent procedure for "drawing up" or "pinching up" a skinfold and making the measurement with the caliper. The following procedures should be used for each skinfold site.

1. Lay the caliper down on a nearby table. Use the thumbs and index fingers of both hands to "draw up" a skinfold or layer of skin and fat. The fingers and thumbs of the two hands should be about one inch apart, or half an inch on either side of the location where the measurement is to be made.

2. The skinfolds are normally "drawn up" in a vertical line rather than a horizontal line. However, if the natural tendency of the skin aligns itself less than vertical, the measurement should be done on the natural line of the skinfold, rather than on the vertical.

3. Do not "pinch" the skinfold too hard. Draw it up so that your thumbs and fingers are not compressing the skinfold.

4. Once the skinfold is "`drawn up," let go with your right hand and pick up the caliper. Open the jaws of the caliper and place them over the location of the skinfold to be measured and one-half inch from your left index finger and thumb. Allow the tips, or jaw faces, of the caliper to close on the skinfold at a level about where the skin would be normally.

5. Let the reading on the caliper "settle" for two or three seconds, then note the thickness of the skinfold in millimeters.

6. Three measurements should be taken at each location. Use the middle of the three values to determine your measurement. For example, if you had values of 10, 11, and 9, your measurement for that location would be 10. If the three measures vary by more than 3 millimeters from the lowest to the highest, you may want to take additional measurements.

Skinfold Locations for Women

A.Triceps Skinfold—Make a mark on the back of the right arm, one-half the distance between the tip of the shoulder and the tip of the elbow. Make the measurement at this location.

B.Iliac Crest Skinfold—Make a mark at the top front of the iliac crest. This skinfold is taken slightly diagonally because of the natural line of the skin.

C.Thigh Skinfold—Make a mark on the front of the thigh midway between the hip and the knee. Make the measurement vertically at this location.

Skinfold Locations for Men

A.Thigh Skinfold—Make a mark on the front of the thigh midway between the hip and the knee. Make a vertical measurement at this location (same as for women above).

B.Chest Skinfold—Make a mark above and to the right of the right nipple (one-half the distance from the midline of the side and the nipple). The measurement at this location is often done on the diagonal because of the natural line of the skin.

C.Abdominal Skinfold—Make a mark on the skin approximately one inch to the right of the navel. Make a vertical measurement at that location.

Determining the Waist-to-Hip Circumference Ratio

The Waist-to-Hip Circumference Ratio is recommended as a good index for determining risk of disease associated with fat and weight distribution. When a person has both high fatness and a high waist-to-hip ratio, additional risks exist. The following steps should be taken in making measurements and calculating the waist-to-hip ratio.

1. Both measurements should be done with a nonelastic tape. Make the measurements while standing with the feet together and the arms at the sides, elevated only high enough to make the measurements. Be sure that the tape is horizontal around the entire circumference. Record scores to the nearest millimeter or 1/16th of an inch. The tape should be pulled snugly but not to the point of causing an indentation in the skin.

2. Waist Measurement. Measure at the natural waist (smallest waist circumference). If there is no natural waist, the measurement should be made at the level of the umbilicus. Measure at the end of a normal inspiration.

3. Hip Measurement. Measure at the maximum circumference of the buttocks. It is recommended that the measurement be made in briefs that do not add significantly to the measurement.

4. Calculate your waist to hip ratio by dividing your hip measurement into your waist measurement.

Height-Weight Measurements

1. Height.

Measure your height in inches. Take the measurement without shoes, but add 1 inch to measurements, as the charts are based on heels of this height.

2. Weight.

Measure your weight in pounds without clothes. Add 3 pounds because charts are based on clothes of this weight. If weight must be taken with clothes on, wear indoor clothing of 3 pounds in weight.

Body Mass Index (BMI)

The body mass index (BMI) is a method of using height and weight to assess body composition and disease risk. BMI is considered to be a better measure than height and weight alone.

If you have already determined your height and weight you may click on the Fitness Profile button and let the computer compute your BMI and your your rating for the BMI.

Or you can use the formula at the right to calculate your BMI.

1. Divide your weight in pounds by 2.2 to determine your weight in kilograms.

2. Multiply your height in inches by .0254 to determine your height in meters.

3. Square your height in meters (multiply your height in meters by your height in meters).

4. Divide the value you obtain in step 3 (square of height in meters) into the value you obtain in step 1 (weight in kilograms).