Body Fat – Does Yours Measure Up?
The term body fat refers to the excess fat stored by the body. Basically body fat is a store of energy that has not yet been utilized by the body; body fat is created when one ingests a greater amount of calories than that which is required to carry out the day to day functions of the body. The excess calories are stored as fat throughout the body and is classified as both essential body fat and nonessential body fat.
Essential body fat is required by the body to function properly; it is responsible for the regulation of body temperature, optimal functioning and cushioning of the internal organs and also as an emergency source of energy during illness. This essential body fat has a percentage measure of 2-4% for men and 10-12% for women, below these levels poses a serious risk to the health of the individual. Excess or nonessential body fat however can be dangerous and lead to serious health problems and is associated with type 2 diabetes, hypertension and hyperlipidemia.
The fat free mass exists primarily as the chief structural and functional component of the human body. Fat free mass consists of water (72%) protein (21%) and a bone mineral (7%) typically an adult has only 3-4kg bodyweight from bone.
Fat mass varies considerably between individuals, in terms of absolute amount. Fat mass consists of 20% water and 80% adipose tissue. Healthy ranges of body fat range from between 14-20% for men, a percentage of greater than 25% is considered to be unhealthy and puts the individual at an increased risk of obesity related illness. Healthy ranges for women range between 17-24% where a level of 30% body fat is considered unhealthy and at a level of increased risk.
The American Council of Sports Medicine ranges the acceptable and recommended percentage body fat it the table below:
|10 - 12%
|2 - 4%
|14 - 20%
|6 - 13%
|21 - 24%
|14 - 17%
|25 - 30%
|18 - 25%
Methods of evaluating body fat
There are numerous methods of evaluating body fat, for both the clinical setting and in the field. The degree of accuracy associated with each procedure, increases as we move from the field to the clinical setting, such as skinfold measurements compared to DEXA. Also methods of measurement are more suitable for one sample group than another, for example the Body Mass Index (BMI) is more suited to measuring body composition in sedentary folk than athletes, due to the fact that athletes (depending on their chosen sport) will have a higher lean body mass and may fall into the wrong category by BMI standards (football players, rugby players, bodybuilders). A more suitable approach to measuring a group of athletes would be the skinfold measurement as it would provide a more accurate prediction of percentage body fat for that particular sample group (Than BMI). Below are numerous methods used for the measurement of body fat and a brief summary of how they work. Click link for a full description.
Chemical ingestion and the subsequent analyses of the tissues is the only direct method of evaluating body composition, which is a totally impractical approach in humans. DEXA, hydrostatic weighing and plethysmography are highly accurate but expensive methods requiring clinic settings to perform the test, making them unsuitable field methods of measurement. Bioelectrical Impedance Analysis and skinfold measurement however are inexpensive, easy to perform and can be completed in relatively little time. The protocols which have to be in place when using the BIA method also pose a problem for an accurate estimation of percentage body fat, leaving skinfold measurement as the current forerunner for accurate field testing.
For more information, read the article on "The Role of Body Fat Evaluation in human function and performance."