Body fat percentage

The body fat percentage is the amount of accumulated fat in proportion to the total mass of the body. But it does not allow any conclusions about the ratio between Struktur-/Bauchfett and depot fat is. The latter can lead to increased incidence in cardiovascular disease and is therefore sometimes considered one of the four clinical features of the metabolic syndrome.

The body fat percentage is the basis for calculating other indicators, such as the fat -free mass index and the controversial rock quotient.

Measurement methods

The body fat ratio can be measured by various methods. As complicated and expensive, but unsurpassed reference methods volume measurement methods and DEXA apply. The latter is rarely used due to high radiation exposure.

A mechanical process

Skinfold thickness by Caliper - Calipometrie refers to the measurement of skin fold thickness with a caliper ( Caliper ), which is performed on up to nine points on the whole body. It is in everyday medical practice is important.

Disadvantage of this method is that more needs to be measured by the same person, because not every examinee selects exactly the same measurement points and apply exactly the same force in the necessary manual wrinkling.

The advantage over electrical measurement methods is that drinking coffee or alcohol, etc. do not matter. And it does not matter, whether before or after a workout is measured as the measured subcutaneous fat can not be so short or dismantled. However, can affect the measurement after strenuous exercise or a sauna session a temporarily increased water retention under the skin.

It is doubtful whether the Caliper is suitable as a method for absolute body fat determination, since it will not imply body fat can be measured. However, to document the trends it is best suited. For the evaluation, there are several software on the market, such as MiniFatCal or Body Attack.

Radiation measurement method

• Three -Dimensional Photonic Bodyline Scanner - Imaging method using an ultrasound scanner ( without exposure to radiation ). This is a method for the measurement of body fat ( both at a clearly defined point as well as the total). Here, the thickness of fat layers and muscle is measured by means of ultrasound. Characterized accurate readings are possible - as opposed to an extrapolation from a point on the body, as is the case with the measurement by Caliper. Due to variations to DEXA and hydrodensitometry the elegant method could not very spread.

• Whole body DEXA measurement - DEXA ( dual energy x - ray absorptiometry ) is a radiological technique wherein the body is scanned by X-rays, which can determine the amount of body fat, lean muscle mass and bone. Due to the radiation exposure and its associated costs, these highly accurate method, however, is not generally applicable. In Germany it is not allowed by law in adolescents.

• 40K measurement - Another method is the 40K measurement, in which the activity of the stored in the muscles naturally radioactive isotope potassium -40 ( 40K ) measured by whole body counter, it can be concluded from which to fat content of the body, the higher the average activity per kg of body weight, the lower the fat percentage.

Electrical method

In everyday medical is not only to measure body fat with a body fat bathroom scale and a bioelectrical impedance analysis (BIA ) is a quantitative, yet relatively simple way to determine your body fat percentage. Meanwhile, there are already body fat scales that measure body fat percentage and bone mass.

Volume measurement method

• Hydrodensitometry - Below is the volumetric determination of water displacement in a kind of bathtub to understand. The displacement is set in relation to body weight. Annoying for the test is the total immersion; with the necessary breath arise thus usually measuring times of about half an hour. Therefore, the method is not suitable for everyday use, but serves only as a reference.
• Air Displacement Plethysmography or Luftverdrängungsplethysmographie ( ADP) - ADP uses air displacement instead of water displacement in the hydrodensitometry. This eliminates the hassle of immersion of the subjects and the measurement time is shorter (only 10 minutes).

Chemical methods of measurement

• Sulfur hexafluoride dilution method - In Japan, developed and used, the method is based on pressure changes due to heat loss through the body. Due to variations to DEXA and hydrodensitometry rather unpopular.

Normal values ​​and limits

Medical recommendations and standard values ​​for body fat percentage will depend on age, gender and body type. Twenty -year-old men have a body fat percentage of 18%, young women on average of 25%. With age, this proportion increases while lean body mass decreases due to the loss of muscle tissue. At the age of 45 years in men body fat percentages of 22-24 % typical, at such women by about 30%. A healthy body fat percentage is women usually below 30% ( better than 25% ) in men under 25 % (better than 20%). Since larger energy reserves to power the next generation needed during pregnancy and lactation, the women have a slightly higher body fat percentage.

Classification body fat, based on Gallagher et al. American Journal of Clinical Nutrition, Vol 72, Sept. 2000

Since this table is addressed to a general audience, there are indeed people with a body fat percentage below the above values ​​, which nevertheless are in good health. To have professional athletes in the age group up to 30 years usually have a body fat percentage of about 8-12 %. The body fat percentage of a male professional bodybuilder is during the competition season at approximately 5% or just below. As a vital applies to men a body fat percentage between 2 and 5 percent, for women a 10-13 per cent.