Reporting in the July 5 Journal of the American Medical Association, researchers at the University of Pittsburgh analyzed data on weight, death, and cardiovascular disease among more than 90,000 ethnically-diverse U.S. women followed for an average of seven years.

They concluded that the health risks of women who are extremely obese may have been underestimated.

There are three categories of obesity, according to background information in the study: obesity 1 (a body mass index of 30 to 34.9); obesity 2 (BMI of 35 to 39.9); and obesity 3 (BMI of 40 or greater). A 5-foot, 4-inch person who weighs 233 lbs. would have a body mass index of 40.

The latter two categories (sometimes termed severe obesity) are becoming more common in the United States. From 1986 to 2000, the prevalence of women with severe obesity quadrupled, the researchers noted, and by 2000, two percent of all U.S. women were severely obese.

The study found that the higher a woman's level of obesity, the greater her health risks.

"Accounting for degree of excess weight is important in understanding [women's] weight-related health risk," the researchers reported. "Overall, extremely obese women were more likely to die over the average seven years of follow-up than were women in other examined weight categories."

"More accurately assessing weight-related health risk may both improve policy decisions about obesity and assist women in making informed decisions about their health," they added.

-- Robert Preidt