How is obesity measured? Obesity is generally measured on a scale of Body Mass Index also known as BMI. Doctors and scientists generally agree that men with more than 25 percent body fat and women with more than 30 percent body fat are obese. However, it is difficult to measure body fat precisely. There are multiple methods of measuring obesity. The body mass index (BMI) has become the medical standard used to measure overweight and obesity.

BMI

• In recent years, the body mass index (BMI) has become the medical standard used to measure overweight and obesity.
  
• It is a height-weight system of measurement that applies to both sexes.
  
• It's not a perfect system, because (e.g.) very muscular people may fall into the "overweight" category when they are actually healthy and fit.
  
• But it is a useful pointer for most people. .
  

Body Fat Distribution: "Pears" or "Apples"

Other Methods of Measuring Fat

• The most accurate measures are to weigh a person underwater or to use an X-ray test called Dual Energy X-ray Absorptiometry (DEXA). These methods are not practical for the average person, and are done only in research centers with special equipment.
  
• Skinfold thickness' are measures of the thickness of skin and subcutaneous (lying under the skin) fat at targeted sites of a person's body such as the triceps (the back of the upper arm). Measurements of skinfold thickness depend on the skill of the examiner, and may vary widely when measured by different examiners.
  
• Weight-for-height tables, usually have a range of acceptable weights for a person of a given height. One problem with these tables is that there are many versions, all with different weight ranges. Another problem is that they do not distinguish between excess fat and muscle. A very muscular person may appear obese, according to the tables, when he or she is not.