http://www.cnn.com/2009/HEALTH/03/18/healthmag.obesity.lifespan/index.html

Obesity can shorten lifespan up to a decade

Story Highlights
* Study: Obesity shortens life by 2-4 years; the very obese could lose up
to 10 years

* Higher mortality because of diabetes, cardiovascular, kidney and liver
disease

* Cancer deaths also went up with increasing BMI, but not as much as other
diseases

* Another study had found that being overweight, but not obese, didn't
shorten life

By Anne Harding
Obesity shaves two to four years off the average lifespan, while being very
obese can shorten your lifespan by 8 to 10 years, according to a new
analysis of 57 studies including nearly 900,000 people.

"This is scary and something that we should pay close attention to," says
Ali Mokdad, Ph.D., a professor of global health at the Institute for Health
Metrics and Evaluation at the University of Washington in Seattle. The new
findings actually underestimate the true impact of obesity on society
because they don't address the costs of obesity-related illness and other
factors, says Mokdad, who was not involved with the current study.

The study, published online March 18 in the journal The Lancet, was
conducted in part by the eminent epidemiologist Sir Richard Peto of the
University of Oxford. Peto and his colleagues in the Prospective Studies
Collaboration, a team of dozens of researchers from around the world, say
they did the new study to figure out exactly how body mass index (BMI)
relates to mortality. Researchers also investigated how smoking influenced
this relationship and how excess weight affected death risk from specific
causes.

Their analysis included 894,576 people, mostly from North America and
Western Europe. Most were age 46 when the study started and were recruited
in 1979; the average BMI for all participants was 25. The researchers
eliminated deaths during the first five years of their analysis to avoid
including people who were excessively thin because of illness.

A BMI of 18.5 to 24.9 is normal (that translates to weighing between 114
and 149 pounds if you're 5 feet 5 inches tall); overweight is 25 to 29.9
(150 to 179 pounds if you're 5 feet 5 inches tall); and obese is 30 or more
(180 pounds-plus on a 5-foot-5-inch frame.) You can figure out your BMI at
the National Institutes of Health Web site.

Men and women in the new analysis who had BMIs between 22.5 and 25 were the
least likely to die during the follow-up period, which averaged eight
years. But every additional 5 BMI points boosted mortality risk by 30
percent. The increase was strongest for deaths due to cardiovascular
disease, diabetes, kidney, and liver disease; cancer deaths also went up
with increasing BMI, but not as much as other diseases. Health.com: How to
find your healthiest body mass index

People with BMIs below 22.5 had a higher mortality risk during the study
than those who weighed slightly more, largely because of respiratory
illnesses, such as lung cancer. The researchers say this is probably the
result of skinny people who were smokers.

The researchers calculate that having a BMI of 30 to 35 takes to two to
four years off the average lifespan compared with having a BMI of 22.5 to
25. Having a BMI between 40 and 45 (for example, being 5 feet 5' and
weighing 240 to 270 pounds), they say, reduces one's lifespan by eight to
10 years. This reduction in lifespan is on par with being a heavy smoker.
Health.com: Dietary fats can help -- or harm -- your heart

This isn't too far out of line with research conducted by Katherine M.
Flegal, Ph.D., a senior research scientist and distinguished consultant
with the Centers for Disease Control and Prevention's National Center for
Health Statistics.

In a 2005 study, Flegal and her team reported that while being obese
(having a BMI of 30 or above) shortened lifespan, those who were overweight
(a BMI of 25 to 29.9) were at no greater risk of death, and may actually
have had a lower mortality rate in a given time period than their
normal-weight peers. Health.com: How to cut up to 900 calories with simple
substitutions

While the study kicked up a lot of controversy -- some people thought the
findings minimized the health effects of excess weight -- several other
studies have also found no greater mortality risk associated with being
overweight (but not obese), and possibly lower mortality, Flegal notes.

Given the difficulty of losing weight, the authors of the new study say, it
may be best if people are motivated to prevent the weight gain in the first
place. For example, a person who held their BMI steady at 28 rather than
going up to 32 (typical of the increase seen in middle age) could extend
their life by two years, the researchers say, while a young adult who
maintained a BMI of 24 rather than going up to 32 could add three years to
his lifespan. Health.com: BMI success story: How one woman lost 44 pounds

For this to happen here, Mokdad notes, the United States government is
going to have to do a much better job of supporting prevention efforts. A
"bailout" for such efforts that translated to healthier American and
workers could be a pretty effective economic stimulus, he added.