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While I don't disagree that many people in general are overweight, any report that makes claims based on BMI is bogus.

ksaj 7y ago
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.

ksaj 7y ago

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.