What is Body Fat (%) ?

Body fat is considered an energy reserve, and deposited fat provides a number of other functions. It serves as a protective cushion and provides structural support to prevent injury to vital organs such as heart, liver, kidneys, and spleen. It also insulates the body from heat loss and extreme temperature changes and this deposits under the skin may be metabolized to generate heat in response to lower skin temperatures. Lipids yield 9 kcal of energy per gram while carbohydrates and proteins yield only 4 kcal of energy per gram. Most of the fat in food is in a form of triglyceride. Fatty acids are classified according to their degree of saturation as saturated, monounsaturated and polyunsaturated fatty acids. For these fatty acids are hydrophobic, they are transported in the blood in the form of lipoprotein.

There are various methods used to estimate body fat, such as Bioelectrical Impedance Analysis (BIA) which utilizes a well-known principle in which an electric current sent through the body will react differently to body fat compared to muscle and other types of tissue.

Fat is the most concentrated source of energy in the body, and in excess, it may be harmful to health. Excess of body fat, higher than standard values adjusted to weight, is considered obesity, and it accumulates in abdomen or subcutaneously.

Body fat percentage standards differ by age group and sex, and there is no single unified standard. Below is an example of body fat percentage standards for different age and gender groups: 

Body Fat (%)

Age	Female	Male
10~34	20.9%~32.5%	8.6%~19.3%
35~49	23.5%~35.1%	11.8%~22.5%
50~80	24.5%~36.1%	13.8%~24.5%

Reference: Daniel P.Williams, Scott B. Going, Timothy G. Lohman, David W. Harsha, Satharnur R. Srinivasan, Larry S. Webber, Gerald S. Berenson, Body fatness and risk for elevated blood pressure, total cholesterol, and serum lipoprotein rations in children and adolescents. American journal of public health, March 1992 , Vol. 82, No.3.