Topic: Body

Obesity - Part I - Definition and Measurement

Aug 20, 2007


Generally speaking obesity is when one has excessive body fat. It is not exactly overweight, because additional weight could be because of muscles, heavy bones and body water.

A person may suffer from obesity if he or she consumes more calories than use. Each person has different amounts of calories consumed and used. The balance can be tipped due to such factors like: genetic makeup, overeating, especially food containing a lot of fat and inactive way of life.

Obesity can rise the risk of some serious health problems, including: diabetes, heart disease, arthritis and even cancer.

It is worth mentioning that as a rule women have more fat in their bodies than men. A lot of doctors and professionals from the field of health care agree on the fact that men, having more than 25 percent of body fat, and women with above 30 percent of body fat are considered to suffer from obesity.

However, this must not be confused with the body mass index (BMI). The latter is often used by health care professionals in order to figure out the effect of body weight on the risk of some specific diseases.

Obesity Measurement

First of all it is worth mentioning that it is not easy to calculate the amount of one's body fat. Some of the most accurate types of measurement are considered the following:
  • weighting underwater or inside a chamber which uses air displacement, in order to measure the volume of the person's body;
  • using X-ray test; this one is called Dual Energy X-ray Absorptiomentry. The test is also known as DEXA.

The two popular and effective methods, however, are not quite practical for an average person. They are performed only in special centers with the use for special equipment.

Some simpler methods of measuring body fat can be used. These include the following:
  • measuring the thickness of the layer of fat, which is just under a person's skin in several body parts.
  • Sending electricity in a harmless amount through one's body.

In case these methods are made by a person with little experience in the field or someone with extreme obesity, the results might be rather inaccurate.


The body mass index is a tool used for assessing obesity and monitoring any changes that occur in the weight of a person's body. This tool, however, has its disadvantages, and namely - it does not estimate body fat or muscle directly. BMI is measured by dividing one's weight in pounds by height in inches squared and then the result is multiplied by 703. Thus two different persons can have the same body mass index but at the same time completely different fat percentages.

For example a bodybuilder with low percentage of body fat can have the same BMI as a person with excessive body fat. This is because the bodybuilder has a large muscle mass. Excessive amount of body fat can be identified if the BMI is 30 or higher.