What is Body Fat

There is a common misconception that all body fat is bad. In truth, some body fat is needed to protect the person’s health as well as supplying a reservoir of energy for performing various body functions. To better understand this, the total weight of body fat can be subdivided into three separate categories:

Weight of “Essential Body Fat” - This amount of body fat is needed to protect the body from infectious diseases and to protect the internal organs from bruising damage.

Weight of “Reserve Body Fat” – The amount of additional body fat that does not cause any medical risks, and provides a reservoir of “fuel” for use by the body.

Weight of “Excess Body Fat” – The amount of body fat that is over and above the combination of Essential Body Fat plus Reserve Body Fat. Excess Body Fat causes the risk of serious health problems such as strokes, heart attacks, diabetes and certain forms of cancer.

The following further discusses the three parts of the total body fat.


During the development of the FUTREX Body Composition Analyzers, approximately thirty medical “gurus,” that specialized in the study of body fat on human health, were contacted. These experts were asked what minimum percent body fat is necessary to avoid health problems. Although there wasn’t a total consensus, the majority agreed that the minimum healthy body fat is six percent for males, and nine percent for females of normal body weight. These levels are needed to avoid bacterial and viral diseases as well as provide the body with the needed insulation for temperature extremes and to protect internal organs from bruising. This Essential Body Fat can be considered composed of two different components.

The fat layer that is directly under the skin – – – called subcutaneous fat. This fat layer provides thermal protection and bruise protection.

The body fat that is contained in the muscle – – – called intramuscular fat. This is similar to the thin layers of fat you see within meat when you buy a well trimmed steak from a butcher. This fat provides an emergency “fuel” source for the total body and “cushions” (i.e., protects) the vital organs from shock forces. The minimum percent body fat is higher for females than for males because of reproduction needs as well as other body functions.

Admittedly, world class athletes, in order to achieve maximum speed and agility, have body fat below the recommended levels for “Essential Body Fat.” For example, world class runners have body fat typically between three and four percent. Similar low levels are typical of professional football wide receivers. Another example, world class gymnasts typically have body fat below three percent. In fact, no member of the United States Olympic Gymnastics Team had body fat above three percent. Yet, it is widely known that such low percent body fat can cause severe health problems later in life.


In the last twenty years, the scientific literature contains many studies to determine what level of body fat is allowable before introducing health risks. Many of these studies were performed at the Cooper Institute  (Dallas, Texas), and by the National Institutes of Health’s Framingham Studies.

The scientific literature shows that the maximum amount of allowable Reserve Body Fat is a function of a person’s height, age, and gender. For example, a six foot tall male who is 35 years old can have Reserve Body Fat anywhere between 0 lbs. and 23 lbs. However, for a male 55 years old and six feet tall the allowable Reserve Body Fat can be anywhere between zero and 30 pounds without increasing his health risks.


Any amount of body fat over and above the combination of Essential and Reserve Body Fat introduces serious health risks. Moreover, NIH research shows that these risks increased as the amount of Excess Body Fat increases. From the accompanying figure, two facts are obvious:

  • It is much better to be underweight than it is to be overweight (there is much lower “mortality ratio”; i.e., the statistical death rate is lower).
  • As you become more overweight, the curve tends to run away. In other words the risk of death is greatly increased.