It's been assumed that U.S. life expectancy would rise indefinitely, but a new data analysis, published as a special report in the March 17 New England Journal of Medicine, suggests that this trend is about to reverse itself -- due to the rapid rise in obesity, especially among children.
A review by obesity researcher David Ludwig of Children's Hospital Boston, epidemiologist S. Jay Olshansky of the University of Illinois at Chicago, and colleagues concludes that obesity now reduces average life expectancy by about 4 to 9 months, a conservative estimate. More ominously, the researchers further conclude that if the current epidemic of child and adolescent obesity continues unabated, life expectancy could be shortened by two to five years in the coming decades.
The researchers based their predictions on data on the prevalence of obesity from the National Health and Nutrition Examination Survey and previously published estimates of years-of-life lost from obesity. A reduced life expectancy could have implications for such programs as Social Security and Medicare, they suggest.
Current trends indicate that the prevalence of obesity will continue to rise and affect ever-younger age groups, especially among children, the researchers note. Minority groups are expected to be hardest hit because of their reduced access to health care and especially sharp increases in childhood and adult obesity.
The long-term consequences of the child obesity epidemic have yet to be seen, says Ludwig, who directs the Optimal Weight for Life (OWL) program at Children's Hospital Boston. Obesity is known to increase risk for heart disease and cancer, and the surge in childhood obesity has already triggered an unprecedented rise in type 2 ("adult") diabetes in children.
"The tsunami of childhood obesity has not yet hit the shore -- it takes many years for complications to develop," Ludwig says. "If the clock starts ticking at age 12 or 14, the consequences to public health are potentially disastrous -- imagine heart attack or kidney failure becoming a relatively common condition of young adulthood."
Two thirds of American adults today are obese or overweight, and the proportion of people with extreme obesity has risen especially rapidly, the investigators note. Thus far, medical treatment has had little success in offsetting this trend.
Ludwig attributes much of the obesity epidemic to environmental factors. "If we were to reverse environmental factors back to those of the 1960s, most of the obesity epidemic would disappear," he asserts.
In the past 40 years, fast food, junk food, and soft drinks have become a prominent part of the landscape. Food advertising directed at children has exploded, and portion sizes have ballooned (see attached fact sheet). Schools have become purveyors of fast food and soft drinks through contracts with the food and beverage industry that help fund school programs -- even as they cut physical education classes from their curricula to save money. At the same time, children are becoming more sedentary, spending more time watching TV and using computers.
Moreover, many insurance companies don't cover obesity treatment, or offer only limited coverage. Nationally, reimbursement is as little as 10 percent, Ludwig notes.
"To tackle obesity we will need unambiguous political leadership at all levels of government, to make clear that public health has to come before private profit," he says. "This means a fundamental shift in the social environment that will support healthful eating and an active lifestyle. While the campaign must be led by government, it will require the active participation of primary care physicians, nutritionists, schools, and parents."
Founded in 1869 as a 20-bed hospital for children, Children's Hospital Boston today is the nation's leading pediatric medical center, the largest provider of health care to Massachusetts children, and the primary pediatric teaching hospital of Harvard Medical School. In addition to 325 pediatric and adolescent inpatient beds and comprehensive outpatient programs, Children's houses the world's largest research enterprise based at a pediatric medical center, where its discoveries benefit both children and adults. More than 500 scientists, including eight members of the National Academy of Sciences, nine members of the Institute of Medicine and 10 members of the Howard Hughes Medical Institute comprise Children's research community.