This is partly because they keep defining obesity downward. A squatty person that is not overweight (just bulky - think Samoans and some Mexicans) is now considered obese with their one-size-fits-all guidelines that don't even take gender into account.
The health care folks know they have a gold mine on their hands with the obesity "crisis" made worse by narrowing the CDC standards of what is considered a "healthy" weight.
Part of the problem is hard to deny (just stroll through a mall sometime) but don't buy their numbers at face value. They're as drummed up as Clinton's economy numbers.
Oh come on. Obesity - like pornography - you know it when you see it!