yes, unless there is a breakthrough in the treatment of obesity (or a radical change in American habits), the long standing growth in American life-expectancy will likely decline due to obesity and its medical complications. here's a MSM article describing this penomenon:

http://www.cnn.com/2005/HEALTH/diet.fitness/03/16/obesity.longevity.ap/

On the other hand, maybe all our fat citizens will need all that blubber to make it through the winter in "The Long Emergency"...;o)