Most people don’t know that the Body Mass Index (BMI) chart in most doctors offices was created the 1800's by a Belgian mathematician. It is NOT scientific and it wasn't ever meant to be used to determine fitness.
The best article that I have read that explains why the BMI is just plain wrong, is this NPR article by the math guy, Keith Devlin explains The Top 10 Reasons the BMI is Bogus.
It seems simple enough that the push back to updating our health standards comes from those who stand to make gobs of money. The beauty industry, the diet industry and big pharma.
If you want to be healthy, really healthy you might have to stop for a minute and take in the science and realize that Fit people of any size live longer than unfit people of any size. And that is really good news for all of us. Once we realize we don't have to lose weight to get healthy, we just need to move around a bit more, that's when getting fit becomes easier. - MF