They called for a fundamental shift in political leadership to back healthier eating.
It has previously been assumed that US life expectancy would rise indefinitely, but a new data analysis, published as a special report in today's issue of the New England Journal of Medicine (volume 352, pp1138-1145), suggests 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.
David Ludwig of Children's Hospital Boston, epidemiologist S. Jay Olshansky of the University of Illinois at Chicago, and colleagues based their predictions on data showing the prevalence of obesity from the National Health and Nutrition Examination Survey and previously published estimates of years-of-life lost from obesity.
They say that obesity now reduces average life expectancy by about four to nine months, a conservative estimate.
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 diabetes in children.
"The tsunami of childhood obesity has not yet hit the shore - it takes many years for complications to develop," Ludwig said. "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 of the past 40 years. Fast food, junk food, and soft drinks have become a prominent part of the landscape, with a huge increase in food advertising directed at children and ballooning portion sizes have ballooned. At the same time, children are becoming more sedentary, spending more time watching TV and using computers.
Moreover, many insurance companies do not 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 said.
"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."