
About 40% of US adults are obese, government survey finds - elorant
https://apnews.com/a2154b643d53afae2a3654f722a9b60a
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uberman
While I don't disagree that many people in general are overweight, any report
that makes claims based on BMI is bogus.

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ksaj
Since BMI is based on the height/weight ratio of a person, and the survey is
based on average people of a demographic, I think BMI is a reasonable
indicator. Individually BMI is useless, but that's not what it is for, and not
how it is being used here.

If the _average BMI in a particular demographic_ is significantly higher than
it was historically, or significantly higher than other reasonably similar
demographics, it does very strongly suggest something is happening to either
the height or the weight of that population. Since the average number is going
up, it suggests either the population is getting shorter, or wider. Or both.

You'll end up drawing one particular conclusion, and it is quite probably the
correct one: The population is isn't getting shorter, so it must be getting
wider. And the numbers suggests it is a significant amount. You only have to
look around to see visual evidence. Ever compared pictures of groups and
crowds from the 60's and 70's to ones from today? It's glaringly obvious.
There used to be a LOT of skinny adults, and nearly no fat kids. Now skinny
adults are rare, and fat kids abound. (This could actually be a good social
experiment. Bring out those old family vacation pics and do a background
comparison.) Being able to track that population's weight gain by use of BMI
isn't bogus.

Another way to think of it: a rising BMI for an individual either means
they've been morphing into Arnold Schwarzenegger, or George Costanza. A rising
BMI for a population means the _average_ person is morphing into one or the
other. Which one do you think is more likely to be the case?

People (usually overweight ones) automatically discount BMI without
considering its use in the one and only way it is actually useful. Which is
this particular use case.

