TUESDAY, April 10 (HealthDay News) -- The proportion of severely obese Americans -- those with a body mass index of 40 or more -- increased by 50 percent from 2000 to 2005, twice as fast as the increase in moderate obesity, a new study finds.
During that same period, the proportion of overweight people (BMI of 30 or more) increased by 24 percent, and the proportion of those with a BMI of 50 or more increased by 75 percent. In the past 20 years, the largest percentage increases have occurred in the heaviest weight groups, the RAND Corporation study said.
Body mass index, or BMI, is a ratio of weight to height. A typical severely obese man weighs 300 pounds at a height of 5 feet 10 inches, while a typical severely obese woman weighs 250 pounds at a height of 5 feet 4 inches.
"The proportion of people at the high end of the weight scale continues to increase at a brisk rate despite increased public attention on the risks of obesity and the increased use of drastic weight loss strategies, such as bariatric surgery," report author Roland Sturm, a RAND economist, said in a prepared statement.
The study concluded that three percent of Americans are severely obese. Health costs for severely obese people are expected to be double that of normal weight people, while health costs for moderately obese people are expected to be 25 percent more.
From 1998 to 2003, the number of bariatric surgeries in the United States increased from 13,000 to 100,000. An estimated 200,000 bariatric procedures were done in the United States in 2006, the study said.
"The explosion in the use of bariatric surgery has made no noticeable dent in the trend of morbid obesity," Sturm said.
He said the study findings suggest that severe obesity is not a rare condition among certain genetically vulnerable people but, rather, is an integral part of the U.S. population's weight distribution. As the entire population becomes heavier, there are more and more severely obese people.
RAND is a nonprofit research organization. The study is expected to be published later this year in the journal Public Health.
The U.S. National Institute of Diabetes and Digestive and Kidney Diseases outlines obesity-related health problems.
SOURCE: RAND Corporation, news release, April 9, 2007