4 ms·

Many of those metrics are population or sampling measures and are confounded by many factors at an individual level. The most notorious of which is BMI; it is

Many of those metrics are population or sampling measures and are confounded by many factors at an individual level. The most notorious of which is BMI; it is practically a category error to infer someone's health or risk by individual BMI, and yet doing so remains widespread amongst people that are supposed to know better. Instrumentation and testing become primarily useful at an individual level to explain or investigate someone's disease or disorder, or to screen for major risk factors, and the hazards and consequences of unnecessary testing outweigh the benefits in all but a few cases. For which your GP and/or government will (or should) routinely screen those at actual risk, which is why I pooped in a jar last week and mailed it. An athlete chasing an ever-better VO2max or FTP hasn't necessarily got it wrong, however. We can say something like, "Bjorn Daehlie’s results are explained by extraordinary VO2max", with an implication that you should go get results some other way because you're not a five-sigma outlier. But at the pointy end of elite sport, there's a clear correlation between marginal improvement of certain measures and competitive outcomes, and if you don't think the difference of 0.01sec between first and third matters then you've never stood on a podium. Or worse, next to one. When mistakes are made and performance deteriorates, it's often due to chasing the wrong metric(s) for the athlete at hand, generally a failure of coaching.

FeteCommuniste 9mo ago
> The most notorious of which is BMI; it is practically a category error to infer someone's health or risk by individual BMI, and yet doing so remains widespread amongst people that are supposed to know better. BMI works fine for people who aren't very muscular, which is the great majority of people. Waist to height ratio might be more informative for people with higher muscle mass.
- tclancy 9mo ago
  I dunno, basing life decisions off a metric that has a fudge factor built into it to make the regression work feels sub-optimal to me.
  - XorNot 9mo ago
    BMI underestimates in most cases and your body fat is higher then the chart would predict. When people say "oh BMI isn't accurate" it means you are more overweight then it suggests unless you are literally an extreme body builder.
    - Spivak 9mo ago
      This underestimation has a name, "Normal Weight Obesity." Known by the slang "hot guy/girl fit" where the person looks like they would be physically fit because they're skinny but there's no muscle under there.
- jermaustin1 9mo ago
  As a person who has been told I'm "morbidly obese" for decades now, I will say that doctors at almost every level look at your chart not you. I've been told time and time again that until I get my weight under control, my health will suffer. I'm 5'8" and weigh on average 210lbs. My BMI isn't even morbidly obese, it is 31, which is just "regular" obese, but on top of that, a DEXA scan shows that I am actually only 25% body fat, with only 1lb of visceral fat. Doctor's don't care about that, they see on the Epic chart that my BMI is > 30 and have to tell me some spiel about a healthier lifestyle so they check check off a checkbox and continue to the next screen.
  - prmoustache 9mo ago
    > Doctor's don't care about that Literally all of them?
    - jermaustin1 9mo ago
      I can't say literally all, but in my experience with having to get a new GP almost every year because of health insurance changes, location changes, hospital consolidation buying my GPs practice, and multiple doctors retiring or just quitting medicine (my last GP was tired of medicine after practicing for only 3 years). Over the last 20 years, I've had almost 15 GPs across 5 states (NY, NJ, CT, TX, LA). I also have multiple auto immune diseases, so I have had a handful of specialists of various flavors (endocrine, oncology - not for cancer, cardiology, and urology), but only need them occasionally. Almost every single start of every single appointment (including a follow up from just a couple days prior), they comment about my BMI. It is the rare time they don't that I remember. My last urology appointment the doctor was very congenial, didn't even go over the lab work, just said, everything is looking good, asked how I was feeling, everything good, alright, refilled my prescriptions and left.
    - coldtea 9mo ago
      When humans talk, they use generalizations (and don't need to annouce them). Here it means that most doctors don't care about that. Follow that rule next time you read such a statement in a context that's not formal math.
- oarfish 9mo ago
  My understanding is that it doesnt even do that, because it creates false negatives for the so called skinny fat body type: significant visceral fat mass, which is what we are concerned about, but not much muscle or peripheral fat mass, thereby not being flagged by BMI screens, even though they are at risk.
- deleted 9mo ago
  [deleted]
- deleted 9mo ago
  [deleted]
- inopinatus 9mo ago
  > BMI works fine An individual learns nothing from its calculation and it has no clinical value. I receive more constructive feedback from an auntie jabbing me in the chest and saying "you got fat". > the great majority of people There is wide morphological variety across human populations, so, no.
- friendzis 8mo ago
  No. BMI does not work as a diagnostic measure for general population. The range of "normal" BMI values does depend at least on genetic lineage, gender and individual development history. Fine to compare two scandinavian lineage men, but if you compare e.g. a dutch man with an african woman oh boy, you error margins would be mid-to-high single digit units > Waist to height ratio Again, while not a bad metric per se, translates poorly between cohorts.

FeteCommuniste 9mo ago

> The most notorious of which is BMI; it is practically a category error to infer someone's health or risk by individual BMI, and yet doing so remains widespread amongst people that are supposed to know better. BMI works fine for people who aren't very muscular, which is the great majority of people. Waist to height ratio might be more informative for people with higher muscle mass.

tclancy 9mo ago
I dunno, basing life decisions off a metric that has a fudge factor built into it to make the regression work feels sub-optimal to me.
- XorNot 9mo ago
  BMI underestimates in most cases and your body fat is higher then the chart would predict. When people say "oh BMI isn't accurate" it means you are more overweight then it suggests unless you are literally an extreme body builder.
  - Spivak 9mo ago
    This underestimation has a name, "Normal Weight Obesity." Known by the slang "hot guy/girl fit" where the person looks like they would be physically fit because they're skinny but there's no muscle under there.
jermaustin1 9mo ago
As a person who has been told I'm "morbidly obese" for decades now, I will say that doctors at almost every level look at your chart not you. I've been told time and time again that until I get my weight under control, my health will suffer. I'm 5'8" and weigh on average 210lbs. My BMI isn't even morbidly obese, it is 31, which is just "regular" obese, but on top of that, a DEXA scan shows that I am actually only 25% body fat, with only 1lb of visceral fat. Doctor's don't care about that, they see on the Epic chart that my BMI is > 30 and have to tell me some spiel about a healthier lifestyle so they check check off a checkbox and continue to the next screen.
- prmoustache 9mo ago
  > Doctor's don't care about that Literally all of them?
  - jermaustin1 9mo ago
    I can't say literally all, but in my experience with having to get a new GP almost every year because of health insurance changes, location changes, hospital consolidation buying my GPs practice, and multiple doctors retiring or just quitting medicine (my last GP was tired of medicine after practicing for only 3 years). Over the last 20 years, I've had almost 15 GPs across 5 states (NY, NJ, CT, TX, LA). I also have multiple auto immune diseases, so I have had a handful of specialists of various flavors (endocrine, oncology - not for cancer, cardiology, and urology), but only need them occasionally. Almost every single start of every single appointment (including a follow up from just a couple days prior), they comment about my BMI. It is the rare time they don't that I remember. My last urology appointment the doctor was very congenial, didn't even go over the lab work, just said, everything is looking good, asked how I was feeling, everything good, alright, refilled my prescriptions and left.
  - coldtea 9mo ago
    When humans talk, they use generalizations (and don't need to annouce them). Here it means that most doctors don't care about that. Follow that rule next time you read such a statement in a context that's not formal math.
oarfish 9mo ago
My understanding is that it doesnt even do that, because it creates false negatives for the so called skinny fat body type: significant visceral fat mass, which is what we are concerned about, but not much muscle or peripheral fat mass, thereby not being flagged by BMI screens, even though they are at risk.
deleted 9mo ago
[deleted]
deleted 9mo ago
[deleted]
inopinatus 9mo ago
> BMI works fine An individual learns nothing from its calculation and it has no clinical value. I receive more constructive feedback from an auntie jabbing me in the chest and saying "you got fat". > the great majority of people There is wide morphological variety across human populations, so, no.
friendzis 8mo ago
No. BMI does not work as a diagnostic measure for general population. The range of "normal" BMI values does depend at least on genetic lineage, gender and individual development history. Fine to compare two scandinavian lineage men, but if you compare e.g. a dutch man with an african woman oh boy, you error margins would be mid-to-high single digit units > Waist to height ratio Again, while not a bad metric per se, translates poorly between cohorts.