U.S. life expectancy about
to decline
due to growing obesity
A team of researchers led by University of Illinois at Chicago
Professor S. Jay Olshansky is predicting a decline in life
expectancy in the United States later this century.
That prediction, which is based on the
dramatic rise in obesity, especially among young people and
minorities, is from a special report appearing in the March 17 issue
in the New England Journal of Medicine.
The study determines that obesity
currently reduces life expectancy by approximately four to nine
months.
"The magnitude of that effect may
sound trivial to some, but in fact it's greater than the negative
effect of all accidental mortality, such as car accidents, suicides
and homicides combined," said Olshansky, who is professor of
epidemiology in the UIC School of Public Health.
The researchers also predict that
the rapid rise in obesity among children and teenagers in the past
30 years will have life-shortening effects in the future -- perhaps
enough to offset any improvements in longevity from anticipated
advances in biomedical technology.
Researchers also believe the
life-shortening effect of obesity could rise so rapidly in the
United States -- from two to five years in the next 50 years -- that
it may eventually exceed the current life-shortening effects of
cancer or ischemic heart disease.
The findings are contrary to what
some scientists predict about human life expectancy, which assumes
that past increases will continue indefinitely. Most forecasts of
life expectancy are based on historical trends, but the authors
conclude that such estimates fail to consider the obesity epidemic.
Olshansky and colleagues argue
that current extrapolation models used to predict life expectancy do
not take into consideration the health status of people currently
alive.
Longevity predictions are crucial
for health policy and for economic policy as well.
"One of the consequences of our
prediction is that Social Security does not appear to be in nearly
as bad a shape as we think," Olshansky said.
"The obese may be inadvertently
'saving' Social Security, but the obese themselves and the health
care system that cares for them will pay a very heavy price in terms
of higher death rates and escalating health care costs."
To estimate the current impact of
obesity on life expectancy, the researchers calculated how much
longer people would live if obesity did not exist. To do this, they
used recently published health statistics and assumed that everyone
who is currently obese acquired the body mass index of people who
have the lowest risk of death.
By calculating years-of-life-lost
due to obesity and combining that with estimates of the prevalence
of obesity in younger generations, the authors were able to
illustrate that in the coming decades the risk of death from
obesity-related causes is about to rise. The hardest hit will be
minorities, because of limited access to health care and because
they have experienced the most rapid increases in obesity in recent
years, according to the authors.
It is well documented that obesity
is associated with an increased risk of diabetes, heart disease,
cancer and other complications. Obesity and overweight are the
second leading cause of preventable death in the United States. And
the largest increases in obesity have occurred among children and
minorities.
Body weight is affected by many
genetic, psychological and environmental factors that influence diet
or physical activity levels, says Dr. David Ludwig, associate
professor and director of the Obesity Program at Children's Hospital
Boston and a co-author of the study. For children in particular,
fast food, sugar-sweetened beverages and other
high-calorie/low-quality junk foods are major contributors to
obesity.
"These adverse changes in diet
have been driven by a multi-billion dollar marketing campaign by the
food industry aimed at young children," said Ludwig. "Cutbacks in
funding for regular, mandatory PE classes and limited insurance
reimbursement for obesity prevention and treatment are also
contributory."
The researchers predict that
unless effective interventions are developed to reduce obesity,
children today may live less healthy and shorter lives than their
parents.
"In addition to the enormous
economic costs of obesity, the personal toll is incalculable,"
Ludwig said. "The rapidly escalating prevalence of childhood obesity
and its most feared complication, Type 2 diabetes, raises the
prospect of heart attack becoming a common condition of young
adulthood."
The authors expect that this study
will raise awareness of the importance of increased funding for
obesity research and treatment, especially in children. They also
point out that new investment into the Social Security system, while
at the same time under-funding obesity prevention and treatment, is
not sound economic or public health policy.
"Some may view this as
pessimistic," Olshansky said. "But in fact, it is a realistic
assessment of where we are today and where we appear to be headed in
the future. It is a problem that can be fixed.
"One of the reasons that we've
done this is to alert the public to the serious health and
life-shortening effects of obesity, to find ways to treat it more
effectively and to prevent it. If we succeed in our efforts, our
predictions will be wrong. And that's what we hope."
The full text of the article
is available free on the journal's web site at
http://www.nejm.org
Olshansky will also present the
results of the paper at the Second International Conference on
Healthy Ageing and Longevity in Brisbane, Australia on March 20.
UIC ranks among the nation's
top 50 universities in federal research funding and is Chicago's
largest university with 25,000 students, 12,000 faculty and staff,
15 colleges and the state's major public medical center. A hallmark
of the campus is the Great Cities Commitment, through which UIC
faculty, students and staff engage with community, corporate,
foundation and government partners in hundreds of programs to
improve the quality of life in metropolitan areas around the world.
For more information about UIC, please visit
http://www.uic.edu