Obesity may cut a generation's lifespans

RALEIGH, N.C. — For the first time in decades, young adults today might live shorter lives than previous generations, a new study suggests.

In a collaboration between the University of North Carolina-Chapel Hill, Utah State University and the University of Illinois-Chicago, researchers used new statistical tools to predict the number of deaths from obesity-related illnesses.

The team found that the new tools accurately predicted the increase in deaths from coronary heart disease observed in young men over the last decade.

Over the same time period, older methods for predicting death rates continued to paint a sunny picture of improving health and longer lives for Americans of all ages.

The problem with the old methods is that they make predictions based entirely on generations who have already died, according to Dr. Yang Yang, an author on the study and professor of sociology at UNC-CH and the Lineberger Comprehensive Cancer Center.

Though the predictions are meant to be for the living, "their current health conditions are not taken into account," Yang said.

Obesity is among the health conditions that need to be accounted for, Yang argues. For example, in 2009, 29.3 percent of North Carolinians were obese, according to the Centers for Disease Control and Prevention, up from less than 15 percent 20 years ago.

This rise in obesity — and the corresponding surge in associated illnesses such as coronary heart disease and diabetes — is recent enough that predictions relying only on data from past generations can't account for it.

Yet these prediction methods are consistently used by official agencies, including North Carolina's State Center for Health Statistics, to forecast death rates and life expectancies.

There are lots of theories as to which methods are best, said Don Akin, a statistician with the center. But in the end, "ours is fairly easy," Akin said. When sifting through massive numbers of birth and death records, that's a big advantage.

Yang added that the newer, more accurate methods are less known by forecasting agencies outside of the scientific community. "Like all new inventions, it takes time to disseminate," she said.

But with this study demonstrating the accuracy of newer methods, she thinks the time is right for agencies to make the switch.

Better predictions about the true impacts of health problems such as obesity, Yang said, can help us mount a better response.

"The only way that can happen," she explained, "is if we have the right tools and metrics that allow us to see them."