That may be true, but it doesn't automatically mean that 42% of Americans are high risk. This is reflected in the aggregate statistics. Mild obesity is probably not a significant risk factor, whereas severe obesity is a big problem.
The BMI-based definition of "obesity" is a crude qualifier, and the vast majority of the affected will be in the smaller group that is both elderly and obese (esp. considering that age is, by far, the more important factor for serious outcomes.)
The BMI-based definition of "obesity" is a crude qualifier, and the vast majority of the affected will be in the smaller group that is both elderly and obese (esp. considering that age is, by far, the more important factor for serious outcomes.)