WEBVTT - Should we stop using BMI to measure obesity?

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<v Speaker 1>Already and this is this is the Daily Off.

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<v Speaker 2>This is the Daily OS.

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<v Speaker 1>Oh, now it makes sense. Good morning and welcome to

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<v Speaker 1>the Daily OS. It's Friday, the twenty fourth of January.

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<v Speaker 1>I'm Sam, I'm Zara. This week, a group of researchers

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<v Speaker 1>have called for doctors to stop using the body mass index,

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<v Speaker 1>or BMI to define obesity. It's a measurement system that's

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<v Speaker 1>been around since the eighteen thirties, but now experts say

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<v Speaker 1>it might be doing more harm than good. Today we're

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<v Speaker 1>going to break down why this matters and what could

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<v Speaker 1>replace it.

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<v Speaker 2>Sam, this is such an interesting topic and one people

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<v Speaker 2>have very firm opinions on. But I think that before

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<v Speaker 2>we get to I guess this latest news and how

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<v Speaker 2>people are feeling about it, I do just want to

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<v Speaker 2>start at the beginning, and I think a good place

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<v Speaker 2>to start is by defining what exactly BMI is. It's

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<v Speaker 2>one of those things that we throw around as an

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<v Speaker 2>acron but perhaps don't think about very often. And also

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<v Speaker 2>how BMI calculates obesity, what goes into it.

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<v Speaker 1>So it's basically a mathematical formula that takes into account

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<v Speaker 1>your height and weight and gives you a weight range

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<v Speaker 1>and a scale that shows whether you're underweight in the

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<v Speaker 1>target range or overweight. And it was developed in the

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<v Speaker 1>eighteen thirties. It's a very long time, very long time

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<v Speaker 1>ago by a mathematician who was trying to find what

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<v Speaker 1>he called the average male body. So as we were

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<v Speaker 1>learning more about medicine in eighteen thirties, there was only

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<v Speaker 1>about men only, of course, Yeah, then there was this

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<v Speaker 1>drive to figure out a metric that took into account

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<v Speaker 1>more than one measurement. And so even today, what's considered

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<v Speaker 1>a normal BMI is between eighteen point five and twenty five.

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<v Speaker 1>A person with a BMI between twenty five and thirty

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<v Speaker 1>is considered overweight, and a person with a BMI over

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<v Speaker 1>thirty is considered obese. A person is considered underweight if

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<v Speaker 1>the BMI is less than eighteen point five. But here's

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<v Speaker 1>where it all gets a little potentially problematic. Experts say

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<v Speaker 1>it's an incredibly simplified way of looking at health. So

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<v Speaker 1>the Butterfly Foundation, for example, which is Australia's national eating

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<v Speaker 1>disorder charity, has called it outdated because it doesn't take

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<v Speaker 1>into account things like muscle mass, bone structure, age, sex

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<v Speaker 1>or ethnicity.

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<v Speaker 2>I mean, it's incredible when you think about all the

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<v Speaker 2>advancements we've had in so many areas of health. The

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<v Speaker 2>fact that we are using a metric that was conceived of,

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<v Speaker 2>you know, in the eighteen hundreds is fascinating. There was

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<v Speaker 2>a study this week that called into question whether BMI

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<v Speaker 2>is actually the best way to define obesity. Talk to

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<v Speaker 2>me about what they actually found in that study.

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<v Speaker 1>So this study was a cumbination of a number of

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<v Speaker 1>different streams of research, and in twenty twenty two researchers

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<v Speaker 1>essentially made a commission where they were attempting to bring

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<v Speaker 1>together all of these findings to almost once and for all,

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<v Speaker 1>workout whether BMI is the right way to be measuring obesity.

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<v Speaker 1>They had fifty six leading experts in this from different countries,

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<v Speaker 1>and what they found is pretty striking. So they found

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<v Speaker 1>that under the current BMI system, someone might be classified

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<v Speaker 1>as obese but show no evidence of health problems or

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<v Speaker 1>limitations in their daily activities. And on the flip side,

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<v Speaker 1>somebody might develop obesit related diseases without technically being classified

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<v Speaker 1>as obese under the BMI structure. And if you expand

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<v Speaker 1>it beyond that study and look at an analysis from

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<v Speaker 1>other sources over the years, including Harvard University has done

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<v Speaker 1>a lot of work in this space. Then other issues erase.

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<v Speaker 1>You know the fact that a BMI calculation doesn't take

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<v Speaker 1>into account whether you're pregnant an athlete with large muscle mass,

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<v Speaker 1>and that historic calculations were not only, as you said before,

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<v Speaker 1>based on the male, the average male, but the average

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<v Speaker 1>white male. And now we know that body composition can

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<v Speaker 1>vary a lot by race and ethnic group. So I

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<v Speaker 1>guess if you were to bundle up these findings, really simply,

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<v Speaker 1>it's taking something very complex and trying to make it

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<v Speaker 1>simple but potentially failing.

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<v Speaker 2>Okay, So there has been recognition that perhaps the system

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<v Speaker 2>that we've been using for hundreds of years is falling

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<v Speaker 2>short at the moment, and that it is oversimplifying a

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<v Speaker 2>complex matter, as you said, But there needs to be

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<v Speaker 2>some sort of indication as to how somebody's health is faring.

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<v Speaker 2>What are these researchers proposing could be in place of BMI,

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<v Speaker 2>for example, So.

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<v Speaker 1>They haven't agreed upon what measurements specifically should be taken

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<v Speaker 1>to define obesity. You know, whether it's waste measurements, bone density,

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<v Speaker 1>body fat percentage, height, weight, multiples of that, etc. But

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<v Speaker 1>what they have said with some clarity is the definitions

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<v Speaker 1>of obesity, and they've got two different definitions. They've got

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<v Speaker 1>pre clinical obesity and clinical obesity.

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<v Speaker 2>And sorry, so to clarify, that's because the current definition

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<v Speaker 2>is so closely linked to BMI exactly. Okay, So they're

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<v Speaker 2>separating this and they want new definitions of how someone

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<v Speaker 2>can be classified as obese.

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<v Speaker 1>Yeah, and they've kind of done away with the term

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<v Speaker 1>overweight as well, so they're replacing it with this term

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<v Speaker 1>pre clinical obesity and that would be considered a risk

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<v Speaker 1>factor for diseases. Clinical obesity would be treated as a

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<v Speaker 1>standalone illness caused by how body fat affects organs and tissues.

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<v Speaker 1>And so instead of just using BMI, they want doctors

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<v Speaker 1>to be looking at a whole range of measurements, things

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<v Speaker 1>like waste circumference, actual body fat measurements, or something called

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<v Speaker 1>the waste to height ratio. They don't have clarity on

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<v Speaker 1>which one should be the universally recognized measurement. Essentially, it's

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<v Speaker 1>about having as many measurements as possible and as many

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<v Speaker 1>indicators as possible.

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<v Speaker 2>And I guess the issue that lies with that is

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<v Speaker 2>that with BMI, there is an agreed upon universal way

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<v Speaker 2>of measuring this, and it's accessible, it's understands, super easy,

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<v Speaker 2>and it's easy. But I guess that's one of the shortfalls.

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<v Speaker 2>But there's no consensus on what replaces it. So where

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<v Speaker 2>does that leave us? Where does that leave health practitioners?

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<v Speaker 1>Well, I think the research recognized that convenience is a

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<v Speaker 1>large part of why BMI is so popular. If you

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<v Speaker 1>google BMR calculator, you're given hundreds of different calculators which

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<v Speaker 1>all get the same inputs, and they're very easy to

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<v Speaker 1>measure inputs weight and height, that kind of thing. But

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<v Speaker 1>it does lack the nuance that they're looking for here,

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<v Speaker 1>And it's really important because the output of all of

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<v Speaker 1>this is that some people might be getting unnecessarily limited

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<v Speaker 1>in their access to certain kinds of healthcare, while others

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<v Speaker 1>might have their real health issues overlooked. So let's say

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<v Speaker 1>that there's an insurance company that offers a particular type

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<v Speaker 1>of cover to those who, by the BMI standards, are

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<v Speaker 1>classified as obese. There might be somebody who doesn't fit

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<v Speaker 1>that BMI classification, who misses out on particular coverage, even

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<v Speaker 1>though by other measurements they've got obesity related health issues.

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<v Speaker 2>So you just touched on the way in which definitions

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<v Speaker 2>of obesity can touch other areas of society, as you said,

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<v Speaker 2>like private health insurance, but also I guess policy and

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<v Speaker 2>data collection and all of that. So can you just

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<v Speaker 2>talk to me about what would happen if the definition

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<v Speaker 2>were to change and if the metric of obesity were

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<v Speaker 2>to change.

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<v Speaker 1>Yeah, you're right. I mean there's major funding decisions being

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<v Speaker 1>made on how we understand the demographic makeup of Australa

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<v Speaker 1>and what percentage of Australia would be classified as obese.

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<v Speaker 1>It's a really interesting question. As I was looking into

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<v Speaker 1>both health insurance companies and government policy, what I actually

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<v Speaker 1>found was right now, they're not that reliant on BMI,

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<v Speaker 1>and it made me think that maybe we're stuck in

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<v Speaker 1>a bit of a transition zone anyway, and this research

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<v Speaker 1>kind of affirms that. So most private health companies have

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<v Speaker 1>their own BMR calculators, they do their own BMI calculations

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<v Speaker 1>when you're asked to put in your weight and height

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<v Speaker 1>when you register for health insurance, and they're all caught

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<v Speaker 1>in that tension, I think. So I looked at Booper,

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<v Speaker 1>for example, they've got their BMR calculator on the same

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<v Speaker 1>page as an article about the problems of BMI calculations,

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<v Speaker 1>and then you go to a government level and look

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<v Speaker 1>at policy. I was reading the Australian government's National Obesity Strategy,

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<v Speaker 1>which was made in twenty twenty two. It's a ten

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<v Speaker 1>year strategy. In the eighty four page document, BMI is

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<v Speaker 1>only mentioned once, and it's only mentioned once in a

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<v Speaker 1>list of resources that could be offered to the general

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<v Speaker 1>public as an easy way to track health. So a

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<v Speaker 1>change in the wide scale use of BEMI potentially wouldn't

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<v Speaker 1>have that much of an impact on the way our health,

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<v Speaker 1>insurance or government policy systems work. I think it would

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<v Speaker 1>more in the way that we talk about this topic.

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<v Speaker 2>Keen to understand how the health care industry or community

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<v Speaker 2>has responded to this. What have we heard so.

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<v Speaker 1>Dieticians Australia came out strongly in support of the research.

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<v Speaker 1>This week, their president, doctor Fiona Willer, made an interesting

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<v Speaker 1>point about how people in larger bodies often have their

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<v Speaker 1>health concerns either ignored or automatically blamed on their ways,

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<v Speaker 1>and so they're particularly supportive of moving to what they

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<v Speaker 1>call a more modern approach that brings in those factors

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<v Speaker 1>that we've talked about.

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<v Speaker 2>Okay, so this big body of research has been released,

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<v Speaker 2>It's established that there is an issue with the way

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<v Speaker 2>that we are at the moment both measuring and defining obesity.

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<v Speaker 2>It has put forward some suggestions about changing the way

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<v Speaker 2>that this is defined, but hasn't got any I guess

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<v Speaker 2>agreed upon all universal ways to change that metric of

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<v Speaker 2>be and I where does that leave us?

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<v Speaker 1>So I think what the researchers say is the next

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<v Speaker 1>step is to actually implement more complex definitions of obesity

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<v Speaker 1>on top of the research we've already got. And what

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<v Speaker 1>they're trying to get to there is what percentage of

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<v Speaker 1>the population of whichever country they're operating in is actually

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<v Speaker 1>obese by a more nuanced, complex, medically accurate standard. Once

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<v Speaker 1>they have that data that gives a more accurate portrait

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<v Speaker 1>of how the population is health wise, that's when they

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<v Speaker 1>want to then do further research into other options for

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<v Speaker 1>measurement that are available. I have to say that this

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<v Speaker 1>next part of the project, I think for them, is

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<v Speaker 1>going to be complicated because how do you bring in

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<v Speaker 1>other factors of health amongst a population that's already been

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<v Speaker 1>told they are obese or not. It's going to take

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<v Speaker 1>a lot of you know, closed experimentation on working out

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<v Speaker 1>health outcomes and whether there's a particular pattern in people

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<v Speaker 1>who have a certain type of heart disease and whether

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<v Speaker 1>that was related to one measure of obesity that was

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<v Speaker 1>available and not used. It's complicated, and that's why I

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<v Speaker 1>think it's taken forty eight bodies from forty eight different

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<v Speaker 1>organizations to come together for this sort of research. But

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<v Speaker 1>I do think that the overarching theme of all of

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<v Speaker 1>this in terms of the next steps is a broader

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<v Speaker 1>change in how we all think about obesity. And the

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<v Speaker 1>goal that they have set for us is to move

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<v Speaker 1>away from a one size fits all approach. And that's yeah,

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<v Speaker 1>as I said, already happening on a government policy level,

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<v Speaker 1>but we all need to be thinking about how to

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<v Speaker 1>represent a more complex picture of human health.

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<v Speaker 2>And of course we're talking about obesity today, but that

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<v Speaker 2>same kind of nuance based evidence approach can be applied

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<v Speaker 2>to all sorts of different health conditions across the spectrum.

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<v Speaker 2>So Sam, thank you for taking us through that and

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<v Speaker 2>for explaining more on this really significant research. Thanks Sarah,

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<v Speaker 2>thank you for joining us for another episode of The

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<v Speaker 1>My name is Lily Maddon and I'm a proud Arunda

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