Life expectancy has increased slightly, and in particular deaths from heart disease, cancer, and stroke were down.
Still, any minute now, life expectancy will go down. Because OMG this is the first generation to have lower life expectancy that its parents!
Now, could the rise BMI in the 80s and 90s be contributing to a smaller increase in life expectancy? Yes, it could. Do people have a realistic idea of the relationship between BMI and health? No, they don’t.
ETA: Big Fat Blog also has a post about this.