BMI isn’t science. Its an almost 200 year old equation that was arbitrarily fitted to data. There is no go reason square ones height except that it fit the data. The cutoffs are arbitrary and, at least in the US, shifted in 1997.
And there is a growing body of evidence showing it’s not accurate for many cases in addition to the one you provided.
We have better indirect measure and far better direct measures for assessing disease progression and likelihood of disease development. Getting rid of BMI won’t stop fat shaming, but I hope it gives people pause.
I completely agree, we need to move on from BMI. But it’s a bit silly to say it’s BMI isn’t science when it’s been used for the entirety of modern health sciences. People would be shocked by how many crude, yet useful enough measures that health sciences use even today. And it’s notoriously slow/stubborn in adopting the best tools for many methods. Still, humanity has continued to make scientific progress with them.
Show me the science in the particulars and I’m happy to change my mind. Its widespread use in the modern medical system doesn’t make it scientific. We continue to use generally true ideas such as drink water and then wrench them into prescriptive positions like drink 8 cups of water per day. Literally no science to support that claim.
What science would change your mind? There’s never going to be a magical cutoff number for cholesterol or height or weight that separates healthy and not healthy.
Heuristics are useful tools and sometimes that’s the best you get. You need water to live, clogged arteries cause heart attacks, insulin resistance leads to diabetes. Exactly how much of any given thing causes bad outcomes is going to vary case by case, but doesn’t negate trends.
I say all this as a former wannabe body builder who hasn’t had a BMI under 25 in about 20 years, but I still know a BMI of 60 or 80 is no good.
I though I was clear about this, but I’ll reiterate.
That the heuristic is accurate.
That the heuristic is more accurate than other easily applied heuristics.
That when the heuristic makes categories, the categories are backed by studies. These studies would show a statistical increase for specific health outcomes above this cutoff. That line would be tested relative to other proximal lines.
These heuristics would include different recommendations for different populations such as race, biological sex, and age.
A better alternative, as I had previously linked to, would be abdominal fat as measured at the waist. Easy heuristic and closely correlated to CVD.
All of what you say is true, but you’re not address my particular issues.
I was talking about how widespread BMI is used in health sciences, I.e. everything from basic physiology to clinical trials to program evaluation to epidemiology. This is different from medical practice, e.g. family doctor taking your BMI. Whether it makes for good science or not, it’s use makes it part of science and replacing outdated tools is part of the broader scientific process–that doesn’t make the tools “not science”.
You’re asking about “accuracy” which is a good question, as well as “precision”. However in health sciences we usually evaluate such measures more thoroughly with similar concepts of validity (construct and discriminant) and reliability; you’ll also see sensitivity in the literature but it’s a kind of discriminant validity.
So if you do your own search using “BMI” and these terms on PubMed or even Google Scholar, you will find a range or scientific evidence. Most will say BMI is not good but not terrible, even good in some specific contexts. You will also find lots of evidence of how BMI is associated with other health indicators and health outcomes. I’m not going to spend an hour collating this for you. “Review” is also a useful search term. You seem smart enough to do it if you really want it. In any case, the argument is moot because we agree BMI should be replaced.
Edit: okay I was curious comparing BMI to WtHR and actually found a couple cherry-picked examples that might be interesting for you
BMI isn’t science. Its an almost 200 year old equation that was arbitrarily fitted to data. There is no go reason square ones height except that it fit the data. The cutoffs are arbitrary and, at least in the US, shifted in 1997.
And there is a growing body of evidence showing it’s not accurate for many cases in addition to the one you provided.
We have better indirect measure and far better direct measures for assessing disease progression and likelihood of disease development. Getting rid of BMI won’t stop fat shaming, but I hope it gives people pause.
I completely agree, we need to move on from BMI. But it’s a bit silly to say it’s BMI isn’t science when it’s been used for the entirety of modern health sciences. People would be shocked by how many crude, yet useful enough measures that health sciences use even today. And it’s notoriously slow/stubborn in adopting the best tools for many methods. Still, humanity has continued to make scientific progress with them.
Show me the science in the particulars and I’m happy to change my mind. Its widespread use in the modern medical system doesn’t make it scientific. We continue to use generally true ideas such as drink water and then wrench them into prescriptive positions like drink 8 cups of water per day. Literally no science to support that claim.
What science would change your mind? There’s never going to be a magical cutoff number for cholesterol or height or weight that separates healthy and not healthy.
Heuristics are useful tools and sometimes that’s the best you get. You need water to live, clogged arteries cause heart attacks, insulin resistance leads to diabetes. Exactly how much of any given thing causes bad outcomes is going to vary case by case, but doesn’t negate trends.
I say all this as a former wannabe body builder who hasn’t had a BMI under 25 in about 20 years, but I still know a BMI of 60 or 80 is no good.
I though I was clear about this, but I’ll reiterate.
A better alternative, as I had previously linked to, would be abdominal fat as measured at the waist. Easy heuristic and closely correlated to CVD.
All of what you say is true, but you’re not address my particular issues.
I was talking about how widespread BMI is used in health sciences, I.e. everything from basic physiology to clinical trials to program evaluation to epidemiology. This is different from medical practice, e.g. family doctor taking your BMI. Whether it makes for good science or not, it’s use makes it part of science and replacing outdated tools is part of the broader scientific process–that doesn’t make the tools “not science”.
You’re asking about “accuracy” which is a good question, as well as “precision”. However in health sciences we usually evaluate such measures more thoroughly with similar concepts of validity (construct and discriminant) and reliability; you’ll also see sensitivity in the literature but it’s a kind of discriminant validity.
So if you do your own search using “BMI” and these terms on PubMed or even Google Scholar, you will find a range or scientific evidence. Most will say BMI is not good but not terrible, even good in some specific contexts. You will also find lots of evidence of how BMI is associated with other health indicators and health outcomes. I’m not going to spend an hour collating this for you. “Review” is also a useful search term. You seem smart enough to do it if you really want it. In any case, the argument is moot because we agree BMI should be replaced.
Edit: okay I was curious comparing BMI to WtHR and actually found a couple cherry-picked examples that might be interesting for you
https://www.mdpi.com/2072-6643/8/8/512
https://www.sciencedirect.com/science/article/pii/S2405457723021642
https://pubmed.ncbi.nlm.nih.gov/23775352/