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Actually, BMI _is_ a terribly useful metric (and it's unfortunate bashing, nowadays, is an echo chamber phenomenon in fitness circles around the web). The stud

Actually, BMI _is_ a terribly useful metric (and it's unfortunate bashing, nowadays, is an echo chamber phenomenon in fitness circles around the web). The study this is referring to has a small-ish n (36), so, no big deal here - it seems that they took body composition measurements (among many others) without a significant overhead, they even built a lab within the premises of the corporation they were doing the study in. And they got very rich data with it (although the difference in body fat didn't reach significance, others such as waist circumference did). But imagine that they were doing a different study. Something like a cohort, longitudinal and distributed: studying various corporations which use standing desks during a long, long time (a decade?). This would imply many different people collecting data in different context and different times (and, effectively, bothering even more people). Building labs or ensuring similar equipment across the different sites would be very expensive and laborious - not to mention error-prone! Just imagine the overhead of getting body composition indicators - even something simple as asking people to measure their waist, but during a decade across N sites. In this kind of large study, a seemingly simplistic but nonetheless standardized (and, in a way, normalized) indicator such as BMI is an extremely helpful tool. Imagine you want to do an analysis not by weight, but by by "obesity" ranges, or check if "obesity" status changed: getting body composition is nearly impossible, but using the BMI pre-established ranges (lean, normal, overweight, obese) will actually be feasible (you just need height and weight!). And yes, although a bodybuilder will be considered overweight or obese by BMI, remember this is a study with a large enough n - edge cases will eventually average each other and BMI will hold true for the sample. The BMI will be a cost effective (and feasible) solution to analyse something more than weight changes.

tempestn 11y ago
Yes, that's a good point. My statement was a bit tongue in cheek. BMI can be useful if used appropriately, with its shortcomings in mind. It isn't nearly as useful as other metrics for the sort of individual comparison mentioned by the grandparent comment though.
JupiterMoon 11y ago
In that case BMI gets misused a lot. The bashing comes because whilst it may be useful on a large statistically significant population it is nearly useless at an individual level. One can take two people of identical BMI and one can be actually very fat and the other very slim.
- paulojreis 11y ago
  Misused, by whom? I trust my physician to know how to interpret the BMI values. I don't trust my insurance company to do the same, but they're eventually the ones with a large n (so to speak) - ethics aside, if they want a cost-effective way to factor obesity in their premium, BMI might be the way to go. They'll overestimate the premium for the bodybuilder, but they'll get right most of the time. I'd expect most misuse to be by the media and random people in the Internet. In both cases, however, you should already be taking everything - not only BMI stuff - with a grain of salt. P.S. Even at an individual level, BMI will hold true for the large majority. Even you're talking in a fitness forum, most people won't have enough muscle mass to affect the index that much.
  - heynk 11y ago
    I know a guy who is a hardcore triathlete. At one point a few years ago he was doing really well, sponsored athlete, over 210 pounds with only 7% body fat. He was at a regular check up and the nurse looked at the BMI chart, then looked at him and plainly said 'Maybe you should work out more'. Just my anecdata that BMI is misused even in the medical community.
    - JoeAltmaier 11y ago
      Talking about clueless - had a back issue, physical therapist gave me some good exercises. I asked "In winter I get soft, cycle all summer but with snow I need something else. I hate spin classes. What should I do?" She gave me a dozen reps with a rope on my ankle, 4 lbs weight. Now, 20 miles in a short ride is what, about 4000 reps, at quite a bit more than 4lbs. I mentioned this. She said "Lets just start out at 4 lbs and work up slowly". Sometimes I just wonder.

tempestn 11y ago

Yes, that's a good point. My statement was a bit tongue in cheek. BMI can be useful if used appropriately, with its shortcomings in mind. It isn't nearly as useful as other metrics for the sort of individual comparison mentioned by the grandparent comment though.

JupiterMoon 11y ago

In that case BMI gets misused a lot. The bashing comes because whilst it may be useful on a large statistically significant population it is nearly useless at an individual level. One can take two people of identical BMI and one can be actually very fat and the other very slim.

paulojreis 11y ago
Misused, by whom? I trust my physician to know how to interpret the BMI values. I don't trust my insurance company to do the same, but they're eventually the ones with a large n (so to speak) - ethics aside, if they want a cost-effective way to factor obesity in their premium, BMI might be the way to go. They'll overestimate the premium for the bodybuilder, but they'll get right most of the time. I'd expect most misuse to be by the media and random people in the Internet. In both cases, however, you should already be taking everything - not only BMI stuff - with a grain of salt. P.S. Even at an individual level, BMI will hold true for the large majority. Even you're talking in a fitness forum, most people won't have enough muscle mass to affect the index that much.
- heynk 11y ago
  I know a guy who is a hardcore triathlete. At one point a few years ago he was doing really well, sponsored athlete, over 210 pounds with only 7% body fat. He was at a regular check up and the nurse looked at the BMI chart, then looked at him and plainly said 'Maybe you should work out more'. Just my anecdata that BMI is misused even in the medical community.
  - JoeAltmaier 11y ago
    Talking about clueless - had a back issue, physical therapist gave me some good exercises. I asked "In winter I get soft, cycle all summer but with snow I need something else. I hate spin classes. What should I do?" She gave me a dozen reps with a rope on my ankle, 4 lbs weight. Now, 20 miles in a short ride is what, about 4000 reps, at quite a bit more than 4lbs. I mentioned this. She said "Lets just start out at 4 lbs and work up slowly". Sometimes I just wonder.