I would further venture that not only is it not the case that obesity is killing us, we are not in fact experiencing an obesity epidemic. The government has established an arbitrary dividing line between overweight and obese - a BMI of 30. If you're under the number, you're merely overweight. If you're over the number you're obese. Sorry. Word of advice: don't go to a doctor until you get your BMI down to 29.5. Yes, he'll nag you. But he may not load you down with drugs.
So, as Americans have gained, on average, around ten pounds since the 'epidemic' began (they've also grown nearly an inch taller), that's shifted tens of millions of Americans to the right of the line. And so researchers look at the adjusted numbers and shriek, "WTF ? Look at all those obese people! Where the F*** did they come from ?!?!"