The prevalence of extreme obesity is on the rise in the United States, according to a new report from the U.S. Centers for Disease Control and Prevention. Persons who are extremely obese are at a great risk for serious health complications.

A phone survey of 75,600 adults in 1990 was compared with the results of a phone survey of 154,250 adults taken in 2000 that looked at the incidence of class 3 obesity (body mass index equal to or greater than 40). Body mass index of those surveyed was calculated from self-reported weight and height.

The prevalence of class 3 obesity increased from 0.78 percent (1990) to 2.2 percent (2000), according to the report published in the Journal of the American Medical Association. In 2000, class 3 obesity was highest among black women (6 percent), persons who had not completed high school (3.4 percent), and persons who are short.

"The prevalence of class 3 obesity is increasing rapidly among adults," concluded the researchers. "Because these extreme BMI levels are associated with the most severe health complications, the incidence of various diseases will increase substantially in the future."

Other sources: Journal of the American Medical Association