What they found is that, compared to normal weight individuals, those in the overweight category had a lower risk of dying of any cause, and those in the obese category had an elevated risk.

FORBES: How Useful Is Body Mass Index In Predicting Long-Term Health?

However, more than half of those in the obese category were in class 1, and these individuals had no increased risk of dying compared to normal weight individuals.

FORBES: How Useful Is Body Mass Index In Predicting Long-Term Health?