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Oh, now it makes sense. Good morning and welcome to the Daily OS. It's Friday, the twenty fourth of January. I'm Sam, I'm Zara. This week, a group of researchers have called for doctors to stop using the body mass index, or BMI to define obesity. It's a measurement system that's been around since the eighteen thirties, but now experts say it might be doing more harm than good. Today we're going to break down why this matters and what could replace it.
Sam, this is such an interesting topic and one people have very firm opinions on. But I think that before we get to I guess this latest news and how people are feeling about it, I do just want to start at the beginning, and I think a good place to start is by defining what exactly BMI is. It's one of those things that we throw around as an acron but perhaps don't think about very often. And also how BMI calculates obesity, what goes into it.
So it's basically a mathematical formula that takes into account your height and weight and gives you a weight range and a scale that shows whether you're underweight in the target range or overweight. And it was developed in the eighteen thirties. It's a very long time, very long time ago by a mathematician who was trying to find what
he called the average male body. So as we were learning more about medicine in eighteen thirties, there was only about men only, of course, Yeah, then there was this drive to figure out a metric that took into account more than one measurement. And so even today, what's considered a normal BMI is between eighteen point five and twenty five. A person with a BMI between twenty five and thirty is considered overweight, and a person with a BMI over
thirty is considered obese. A person is considered underweight if the BMI is less than eighteen point five. But here's where it all gets a little potentially problematic. Experts say it's an incredibly simplified way of looking at health. So the Butterfly Foundation, for example, which is Australia's national eating disorder charity, has called it outdated because it doesn't take into account things like muscle mass, bone structure, age, sex or ethnicity.
I mean, it's incredible when you think about all the advancements we've had in so many areas of health. The fact that we are using a metric that was conceived of, you know, in the eighteen hundreds is fascinating. There was a study this week that called into question whether BMI is actually the best way to define obesity. Talk to me about what they actually found in that study.
So this study was a cumbination of a number of different streams of research, and in twenty twenty two researchers essentially made a commission where they were attempting to bring together all of these findings to almost once and for all, workout whether BMI is the right way to be measuring obesity. They had fifty six leading experts in this from different countries,
and what they found is pretty striking. So they found that under the current BMI system, someone might be classified as obese but show no evidence of health problems or limitations in their daily activities. And on the flip side, somebody might develop obesit related diseases without technically being classified as obese under the BMI structure. And if you expand it beyond that study and look at an analysis from other sources over the years, including Harvard University has done
a lot of work in this space. Then other issues erase. You know the fact that a BMI calculation doesn't take into account whether you're pregnant an athlete with large muscle mass, and that historic calculations were not only, as you said before, based on the male, the average male, but the average white male. And now we know that body composition can
vary a lot by race and ethnic group. So I guess if you were to bundle up these findings, really simply, it's taking something very complex and trying to make it simple but potentially failing.
Okay, So there has been recognition that perhaps the system that we've been using for hundreds of years is falling short at the moment, and that it is oversimplifying a complex matter, as you said, But there needs to be some sort of indication as to how somebody's health is faring. What are these researchers proposing could be in place of BMI, for example, So.
They haven't agreed upon what measurements specifically should be taken to define obesity. You know, whether it's waste measurements, bone density, body fat percentage, height, weight, multiples of that, etc. But what they have said with some clarity is the definitions of obesity, and they've got two different definitions. They've got pre clinical obesity and clinical obesity.
And sorry, so to clarify, that's because the current definition is so closely linked to BMI exactly. Okay, So they're separating this and they want new definitions of how someone can be classified as obese.
Yeah, and they've kind of done away with the term overweight as well, so they're replacing it with this term pre clinical obesity and that would be considered a risk factor for diseases. Clinical obesity would be treated as a standalone illness caused by how body fat affects organs and tissues. And so instead of just using BMI, they want doctors to be looking at a whole range of measurements, things like waste circumference, actual body fat measurements, or something called
the waste to height ratio. They don't have clarity on which one should be the universally recognized measurement. Essentially, it's about having as many measurements as possible and as many indicators as possible.
And I guess the issue that lies with that is that with BMI, there is an agreed upon universal way of measuring this, and it's accessible, it's understands, super easy, and it's easy. But I guess that's one of the shortfalls. But there's no consensus on what replaces it. So where does that leave us? Where does that leave health practitioners?
Well, I think the research recognized that convenience is a large part of why BMI is so popular. If you google BMR calculator, you're given hundreds of different calculators which all get the same inputs, and they're very easy to
measure inputs weight and height, that kind of thing. But it does lack the nuance that they're looking for here, And it's really important because the output of all of this is that some people might be getting unnecessarily limited in their access to certain kinds of healthcare, while others might have their real health issues overlooked. So let's say that there's an insurance company that offers a particular type of cover to those who, by the BMI standards, are
classified as obese. There might be somebody who doesn't fit that BMI classification, who misses out on particular coverage, even though by other measurements they've got obesity related health issues.
So you just touched on the way in which definitions of obesity can touch other areas of society, as you said, like private health insurance, but also I guess policy and data collection and all of that. So can you just talk to me about what would happen if the definition were to change and if the metric of obesity were to change.
Yeah, you're right. I mean there's major funding decisions being made on how we understand the demographic makeup of Australa and what percentage of Australia would be classified as obese. It's a really interesting question. As I was looking into both health insurance companies and government policy, what I actually found was right now, they're not that reliant on BMI, and it made me think that maybe we're stuck in a bit of a transition zone anyway, and this research
kind of affirms that. So most private health companies have their own BMR calculators, they do their own BMI calculations when you're asked to put in your weight and height when you register for health insurance, and they're all caught in that tension, I think. So I looked at Booper, for example, they've got their BMR calculator on the same page as an article about the problems of BMI calculations, and then you go to a government level and look
at policy. I was reading the Australian government's National Obesity Strategy, which was made in twenty twenty two. It's a ten year strategy. In the eighty four page document, BMI is only mentioned once, and it's only mentioned once in a list of resources that could be offered to the general public as an easy way to track health. So a change in the wide scale use of BEMI potentially wouldn't have that much of an impact on the way our health,
insurance or government policy systems work. I think it would more in the way that we talk about this topic.
Keen to understand how the health care industry or community has responded to this. What have we heard so.
Dieticians Australia came out strongly in support of the research. This week, their president, doctor Fiona Willer, made an interesting point about how people in larger bodies often have their health concerns either ignored or automatically blamed on their ways, and so they're particularly supportive of moving to what they call a more modern approach that brings in those factors that we've talked about.
Okay, so this big body of research has been released, It's established that there is an issue with the way that we are at the moment both measuring and defining obesity. It has put forward some suggestions about changing the way that this is defined, but hasn't got any I guess agreed upon all universal ways to change that metric of be and I where does that leave us?
So I think what the researchers say is the next step is to actually implement more complex definitions of obesity on top of the research we've already got. And what they're trying to get to there is what percentage of the population of whichever country they're operating in is actually
obese by a more nuanced, complex, medically accurate standard. Once they have that data that gives a more accurate portrait of how the population is health wise, that's when they want to then do further research into other options for measurement that are available. I have to say that this next part of the project, I think for them, is going to be complicated because how do you bring in other factors of health amongst a population that's already been
told they are obese or not. It's going to take a lot of you know, closed experimentation on working out health outcomes and whether there's a particular pattern in people who have a certain type of heart disease and whether that was related to one measure of obesity that was available and not used. It's complicated, and that's why I think it's taken forty eight bodies from forty eight different
organizations to come together for this sort of research. But I do think that the overarching theme of all of this in terms of the next steps is a broader change in how we all think about obesity. And the goal that they have set for us is to move away from a one size fits all approach. And that's yeah, as I said, already happening on a government policy level, but we all need to be thinking about how to represent a more complex picture of human health.
And of course we're talking about obesity today, but that same kind of nuance based evidence approach can be applied to all sorts of different health conditions across the spectrum. So Sam, thank you for taking us through that and for explaining more on this really significant research. Thanks Sarah, thank you for joining us for another episode of The Daily os. If you learned something new from today's episode,
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