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Calling all Lurkers: Share your Dreams of Effortposting

It’s been pointed out recently that the topics discussed in the Culture War thread have gotten a bit repetitive. While I do think the Motte has a good spread on intellectual discussion, I’m always pushing for a wider range (dare I say diversity?) of viewpoints and topics in the CW thread.

I was a lurker for years, and I know that the barrier between having a thought and writing a top level comment in the CW thread can loom large indeed. Luckily I’m fresh out of inspiration, and would love to hear thoughts from folks about effortposts they want to write but haven’t gotten around to.

This of course applies to regulars who post frequently as well - share any and all topics you wish were discussed in the CW thread!

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F) Healthy at more weights than you thought. IMO, people overstate the health risks of being overweight and don't sufficiently differentiate between overweight/obese and active/inactive.

I'd be interested in this if someone wanted to dig a bit deeper on the subject. In particular I'd be interested to know if some one could figure out how the original BMI based thresholds were set. I'm particularly interested in knowing why a BMI of 25 is considered unhealthy while a BMI of 18.5 is not. I've yet to see an all causes mortality chart where the point at 25 had a higher hazard ratio than the point at 18.5.

This was of particular interest to me when states were rationing COVID vaccine shots. In the state I was living in, having a BMI of 25 made you eligible for the full two shot sequence before people with a BMI 18.5 were even eligible for one. When I tried to figure out why, the state department of health website referenced the CDC. Clicking three or four times and past a circular reference on the CDC site reached a paper that showed minimum risk around 24, if i recall correctly. I don't think this is the same paper, but It seems to show something similar. With the identified minimums in Figure 2. between 23.7 and 25.9. I still can't fathom how the state health officials justified to themselves prioritizing otherwise healthy 18-39 year olds with a BMI of 25 over 49 year olds with a BMI of 18.5.

I'd also be very interested in high quality population level research that controls for body composition as well as BMI with respect to mortality. Surely for a male at 5'10" (178 cm) it healthier to be 175 lbs (80 kg), BMI of 25, with 15% body fat than 130 lbs (59kg), BMI of 18.6, with 20% body fat.

IIRC for males actual best health outcomes are around 26 -- probably the recommendations were just formed based on the distribution of BMIs in the population (ie. mean of 22.5, 1 sigma 2.5?) -- back when people were way skinnier though.

Unfortunately, I don't think it was that sensible. I've never bothered to dig down through all the references (you have to go back to actuarial tables from 100 years ago), but this review paper quotes a 1995 WHO report (internal citations omitted emphasis mine)

WHO Expert Committee on Physical Status referenced the meta-analysis ... presented the U-shape mortality rates that sharply increased when BMI <18.5 and >30.0 kg/m2 with the acceptable BMI range as 18.5–25.00. The WHO experts underscored that the cut-offs were chosen arbitrarily based on the “visual inspection of the relationship between BMI and mortality”...

I don't understand why you would set the low threshold at the point where the curve turns up sharply, but the high threshold at a point close to the minimum.