That they are fuzzy, to say the least. Just going by what was in the post (I did no independent research):

The difference in spending on people who are overweight and those of normal weight were, for the most part, not statistically significant by themselves. But major differences appeared for those who were obese: The average increase in spending over a person of normal weight was $732 per year - 37.4 percent more.



Altogether, medical spending attributable to extra weight totaled $78.5 billion in 1998, or $92.6 billion in 2002, inflation-adjusted dollars.



Okay, so we find that there are no real differences unless we are talking people who are obese, and then it's $732 per person. If we divide $78.5 billion by $732, we arrive at a figure of over 107 million Americans who are not just overweight, but obese. Now, almost certainly I'm missing something in the original report, but I don't think the percentage is that high.

The solution, of course, will be more control of the individual by the government. Note the pointed reference to government health programs picking up a lot of the tab. This, of course, justifies government interference.