Understanding BMI: Doublethink From the CDC

Compare the following statements from CDC's FAQ about the statistic known as "Body Mass Index" or "BMI".

Calculating the BMI is one of the best methods for population assessment of overweight and obesity.

versus

Most studies have examined the relationship between BMI and risk of disease. Therefore we do not know whether two people with the same BMI but different amounts of fat have different risks for disease.

So while they overstate the value of this statistic in the first statement they hedge by the time they get to question 3.

Dare I ask how both of these statments can be true?

I'm working on a table to show how silly this is, but here is an example:

A man is consdered overweight with a BMI higher than 24.9.

If he is 6'0" tall that means he can weigh no more than 183.3 lbs. without being classed as "overweight" by the CDC. He is "obese" at or above 220 lbs.

Yet to weigh as little as 136.9 is considered "normal". Normal?!? that's death-camp survivor range!

A man I know is a shade over 6 feet tall and his last reliable independent body composition measurement said he had 176 lbs of lean mass. A truly healthy body-fat proportion would be 10%. That would put his net weight at roughly 195.5. Thats well in to the CDC's "overweight" range. To be at the upper borderline of CDC "normal" he'd have to be at 4% body fat. Sorry folks, that really would be unhealthy.

That was three years ago. The subject has been working out since and has put on some muscle mass, what then? This isn't a pro athlete and this isn't a guy who pumps iron for 2 or more hours a day. This is an office-worker who does 10-20 minutes of daily calesthenics and can't stand to do anything physical outdoors from April through September [in central Arizona].

The answer is that the CDC and other BMI advocates are just crazy, and they're able to hide their insanity behind a calculation for which they know they dare not publish tables.