The thing that you have to realize is that the BMI calculation that consideres people Obease is completely irrevelant because it doesn't take bone mass and muscle mass into consideration when doing this calculation.
I am considered obease... I am 6'2" 255 lbs... but most of my weight is muscle. I lift weights 6 times a week and do cardio 3-4 times in the morning each week. my body fat percentage is around 9% but yet I am still considered obease. They need to come up with a better way to measure obeasity because right now pretty much everyone in the NFL is obease.
By the BMI standards I would have to weigh 190 lbs to be considered normal weight... which is rediculous I would be skin and bones at that weight.
I agree, however, there isn't much of an arguement that the US as a whole is getting fatter. Obesity related diseases are the 2nd leading cause of preventable deaths here behind smoking.