April 9, 2007 -- The U.S. obesity rate is growing fast -- but the rate of extreme, morbid obesity is growing three times faster, a RAND study shows.
Obesity means having a BMI (body mass index, a ratio of weight to height) of 30 or higher. Severe obesity -- also called morbid obesity -- begins at a BMI of 40. That's a weight of about 235 for a person who is 5 feet 4 inches tall and a weight of about 280 for a person 5 feet 10 inches tall.
Even more extremely obese people have a BMI of 50 or more: a weight of about 292 pounds for that 5-foot-4 person and about 350 pounds for that 5-foot-10 person.
RAND economist Roland Sturm, PhD, looked at data from a telephone survey of American households. He found some shocking numbers -- especially as people in self-report studies tend to say they weigh less than they really do.
From 2000 to 2005, Sturm found, the U.S. obesity rate increased by 24%. But the rate of severe obesity increased even faster. The number of people with a BMI over 40 grew by 50% -- twice as fast. The number of people with a BMI over 50 grew 75% -- three times as fast.
Doctors, Sturm says, tend to think of morbid obesity as a relatively rare problem that affects a consistently small percentage of the population. But the new findings suggest this isn't so.
Sturm calculates that the percentage of people who suffer morbid obesity grows disproportionately as the population as a whole becomes more and more overweight. That means that even the huge increase in bariatric surgery -- with an estimated 200,000 stomach-reducing procedures in 2006 -- won't have a public health impact.
"The explosion in the use of bariatric surgery has made no noticeable dent in the trend of morbid obesity," Sturm said in a news release.
Everybody knows that exercising more and eating less helps us control our weight. But that isn't easy to do -- especially in our modern environment.
"Car-friendly (and bike/pedestrian-hostile) urban developments, desk jobs, television viewing, and relatively cheap calorie-dense foods" are major factors in the U.S. obesity epidemic, Sturm says. "Environmental interventions to counter the obesity epidemic, similar to tobacco and alcohol policy, would be needed."
However, Sturm notes that such policies are not likely to be enacted in the near future.
Sturm's study will appear later this year in the journal Public Health.