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
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
"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
Sturm's study will appear later this year in the journal Public
By Daniel DeNoon
Reviewed by Louise Chang
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