The Centers for Disease Control and Prevention labels American society as "obesogenic," meaning there's far too much promotion of overeating, eating unhealthy foods and generally living a very sedentary lifestyle. According to data from the National Health and Nutrition Examination Survey, 33.8 percent of American adults are obese, judging by their measure on the body mass index, or BMI scale. BMI is a quick, convenient tool that health care providers use to determine whether you are at risk of obesity. It has proven to be a helpful, but not perfect, proxy for your level of body fat and your risk of conditions like metabolic syndrome and heart disease. BMI is a starting point, however, and it shouldn't be used to fully diagnose you with any medical condition.
Obesity in the U.S.
Publishing in the "Journal of the American Medical Association," CDC researchers found that 32.2 percent of men and 35.5 percent of women are obese. When taking into account those who are overweight along with those who are obese, 68 percent of the adults in the United States have a serious weight problem. Public health authorities are treating growing rates of overweight and obesity as an epidemic. The Trust for America's Health, or TFAH, says adult obesity mushroomed in a short span of time, literally doubling from 1980 to 2010. Both the CDC and the National Institutes of Health have funded long-term research projects, as well as prevention and treatment strategies. Among children, the problem is equally troubling. Children who are overweight and form poor eating and exercise habits generally become overweight adults with poor eating and exercise habits. According to the White House Task Force on Childhood Obesity, 31.7 percent of all children ages 2 to 19 are overweight or obese. TFAH says 10 percent of all medical spending in the United States is due to obesity-related treatments. That's $147 billion each year.
History of BMI
The BMI formula was created by Adolphe Quetelet, a Belgian scientist, in his attempt to determine "averages" in human dimensions. The formula is your weight in kilograms divided by the square of your height in meters. So, for example, a 6-ft., 200-lb. man's BMI would be 27.1. Since its inception, BMI has become an important vital statistic in Western medicine. It took root in the early 1900s when insurance companies started using the formula to prove overweight people died earlier than people of healthy weight.
BMI Scale
When you calculate your BMI properly, you get a number, generally between 20 and 35 -- although with growing weight problems some health care providers see numbers as high as 90. If your BMI is 25 or higher, you are considered overweight. If your BMI is 30 or higher, you are considered obese. Obesity is further broken down to class I -- BMI of 30 to 34.9 -- class II -- BMI of 35 to 39.9 -- and class III -- BMI = 40 -- or "extreme obesity," according to the NIH's Weight-control Information Network.
The Trouble with BMI
BMI is a screening tool, not a diagnostic tool. Research such as that published in the "Archives of Pediatric & Adolescent Medicine" and "International Journal of Obesity" has demonstrated that BMI doesn't always classify people correctly. For example, the scale doesn't distinguish between men and women, fails to take age into account and doesn't discriminate between muscle-bound athletes and regular, overweight people. Still, the CDC, NIH and other public health authorities say it is a helpful tool. The most accurate ways to measure body fatness, such as underwater weighing and dual-energy x-ray absorptiometry, are impractical for a typical health care provider's office setting. But if your doctor suspects you have too much body fat by your BMI, he or she can perform other tests to confirm, such as skin-fold tests and waistline measurements.
References
- CDC: Obesity and Overweight
- CDC: Body Mass Index
- "Journal of the American Medical Association"; Prevalence and Trends in Obesity Among US Adults, 1999-2008; Katherine M. Flegal et al.; January 2010
- White House Task Force on Childhood Obesity: Solving the Problem of Childhood Obesity within a Generation
- Trust for America's Health: F as in Fat: How Obesity Threatens America's Future 2010
- "Future of Children"; Special Issue on Childhood Obesity; Spring 2006
Member Comments