By Lindsey Tanner, AP Medical Writer
CHICAGO -- Being obese at age 20 can cut
up to 20 years off a person's life, with the biggest impact on black men,
according to yet another study that underscores the long-term dangers of
being overweight.
The research appears in Wednesday's
Journal of the American Medical Association and was released a day after
another study that said that being fat at 40 shortens a person's life by
at least three years.
The JAMA study, led by University of
Alabama at Birmingham biostatistician David Allison, found that life
expectancy for 20-year-olds with a body-mass index of at least 45 is 13
years lower for white men and 20 years lower for black men, compared with
people of normal weight.
Body-mass index is a height-to-weight
ratio; 30 and above is considered obese. A person who is 5-foot-4 and 262
pounds would have a BMI of 45 -- and look like a sumo wrestler. But
millions of Americans are that fat, Allison said.
The life-shortening effects were found to
be lower for 20-year-old severely obese white women (eight years of life
lost) and black women (five years lost).
Obesity increases the risk for several
life-threatening conditions, including heart disease, diabetes and some
types of cancer. Allison said younger people are especially vulnerable, in
part because they have more years to live and more time for the obesity to
take its toll.
Dr. JoAnn Manson of Harvard's Brigham and
Women's Hospital said the study helps emphasize that obesity is far worse
than just "a cosmetic problem."
Until this week, data attempting to
quantify the effects of obesity on life span were scarce.
In Tuesday's Annals of Internal Medicine,
Dutch researchers presented data on about 3,400 mostly white, middle-aged
Americans. The researchers found that being overweight at 40 is likely to
reduce life expectancy by at least three years -- as much, they said, as
smoking cigarettes. Obese, or severely overweight people, lost even more
years -- about six or seven.
The JAMA study was based on an analysis
of nationally representative surveys of more than 14,000 Americans.
Life-shortening effects were less
dramatic in people who were less obese. And there were startling racial
differences in how fat people had to be before life expectancy started to
drop.
In blacks, life expectancy was not
shortened in obese men with BMIs under 31 and in obese women under 37. But
in whites, reductions of about one year occurred in young people who were
merely overweight -- in men with a BMI of about 25.5 and in women with a
BMI of about 27.5.
BMIs between 25 and 30 are considered
overweight; the ideal is between 18 and 25.
Allison said the reasons for the racial
differences are unclear. But some researchers have speculated that blacks
may have relatively more lean mass, or muscle, than fat.
A JAMA editorial said the differences may
be due to limitations in the study.
"It would be a great disservice to
blacks if these results were used to promulgate the concept that excess
weight is not harmful to them," said Manson and Shari Bassuk of
Brigham and Women's Hospital.
Source: Worldlink Dot Com: JAMA: Annals
of Internal Medicine.
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