(USA Today) -- The percentage of American adults who are 100 or more pounds over a healthy weight has skyrocketed since 2000, a study released Monday shows.
In 2010, about 6.6% of adults in this country were severely obese -- about 15.5 million people -- up from 3.9% in 2000, says the study from the RAND Corp., a non-profit research group.
"There is no question that severe obesity is going up very fast," says lead author Roland Sturm, a senior economist at RAND. "Severe obesity has severe effects on quality of life, chronic conditions and health care costs."
Extra weight increases the risk of type 2 diabetes, heart disease, cancer and other chronic and debilitating health problems.
About two-thirds people in the USA are either overweight or obese. People are considered obese if they have a body mass index (BMI) of 30 or higher, roughly 30 or more pounds over a healthy weight. People are severely (or extremely) obese if they have a BMI (a height-weight ratio) of 40 or higher. That's roughly 100 or more pounds overweight.
"Moderate obesity (a BMI of 30 or more) has adverse health effects, but severe obesity is in a different league," Sturm says. Severely obese people have far more complex health issues and create different challenges for the health care system, he says. "Moderate obesity increases health care costs by 20% to 30% compared to those at a healthy weight, where severe obesity more than doubles health care costs."
Sturm and colleagues write in the paper: "Physician offices and hospitals require additional resources for severely obese patients, who exceed limits on standard measuring and lifting equipment and may not fit standard imaging equipment, operating tables or wheelchairs."
The new study is based on results of a telephone survey of about 3 million people over a decade from the Centers for Disease Control and Prevention. Because people tend to under-report their weight (more so for women) and over-report their height (more so for men), the researchers adjusted the findings for that potential bias.
The research, published online by the International Journal of Obesity found:
-- Severe obesity is about 50% higher among women than men.
-- It is about twice as high among blacks as Hispanics and whites.
-- The percentage of severely obese who are under 40 is similar to those who are over 40.
"The younger group should normally be less overweight or obese," Sturm says. "Yet for severe obesity, the young age group is already similar."
Sturm speculates that one reason for the overall increase in severe obesity may be that "there is some genetic vulnerability among people, and in this environment where there's an overabundance of food everywhere, people have become severely obese instead of just overweight."
Gary Foster, director of the Center for Obesity Research and Education at Temple University in Philadelphia, says, "It's troubling that those most likely to experience the adverse effects of obesity are increasing so quickly. This has significant economic and public health consequences."
These data suggest the need to engage those with extreme obesity in evaluating bariatric surgery options, Foster says. "We also need more treatments aimed at this group."