Americans face drop in life expectancy

For the first time in recent history, researchers are predicting that the life expectancy of Americans may begin a sustained decline.
The forecast is based on the sharp rise in obesity in today's youth. By the middle of this century, the increased risk of diabetes, heart disease and cancer that they will face could lessen the average life expectancy by two to five years, some say.
In general, longevity predictions are determined by studying historical trends in death rates. Various agencies, such as the US Social Security Administration (SSA), have used this method to predict that the life expectancy of Americans will continue to rise over the next century.
But Jay Olshansky, a biodemographer at the University of Illinois at Chicago, argues that they ignore the effect of obesity on future generations.