Body Mass Index may be misleading for some groups.

The tool most commonly used to determine whether people are overweight or obese appears to give some racial groups a false sense of security — and others unnecessary cause for concern.

The well-known body mass index (BMI) relies on a calculation using height and weight to produce a number. That number enables scientists to gauge the risk of weight-related illnesses such as heart disease, high blood pressure and Type 2 diabetes in populations. A BMI of 18.5 to 24.9 is considered healthy; 25 to 29.9 overweight; and 30 or higher, equal to 186 pounds or more for someone 5 feet 6 inches tall, obese.

But in June, a study of nearly 1,200 people of South Asian, Chinese, Aboriginal and European heritage became the latest to show that current BMI thresholds significantly underestimate health risks in many non-Europeans.

Even when waist size and waist-to-hip ratios were considered, the study found that many in the Asian, Chinese and Aboriginal groups who had "healthy" BMI levels were at high risk of weight-related health problems and didn't know it.

BMI and other body measurement thresholds "do not apply to non-European ethnic groups, and warrant revision," concluded Salim Yusuf, director of the Population Health Research Institute at McMaster University in Hamilton, Canada, in the International Journal of Obesity and Related Metabolic Disorders.

This isn't the first time that the body mass index has been called into question. In 2000, the World Health Organization's Pacific Group suggested setting a BMI of 23 as the threshold for being overweight and 25 for being obese in Asian populations.

The National Heart, Lung and Blood Institute also cautions at its Internet-based BMI calculator that the measurement is less accurate at determining who is overweight and obese among muscular people, who have a BMI of 27 to 30, as well as among the elderly, who lose muscle as they age and may be fatter than the numbers suggest.

"Many of us have begun to realize that body mass index is a very poor measure of adiposity — how fat you are — and how much health risk you face," Yusuf said.

Sally Squires, L.A. Times 7/11/2005

Bonnie - Boy, is this nice to see in print. I have said for years that BMI is a gross miscalculation for gauging overweight and obese individuals. As it is with everything, you need to look at multiple factors to gauge if an individual is of normal weight, overweight, or obese.