Goodbye BMI: A New Perspective on Obesity?

Music. And welcome to Change Your Relationship With Food, the podcast hosted by me, Kyla Holley.

With many years experience as an eating disorder and bariatric therapist, I know exactly what it takes to help you break free from your diet history and develop a more healthy relationship with food. Please follow this podcast to make sure you don't miss a thing. For a long time, we have known that using BMI as some sort of indicator of someone's health status is often very, very inaccurate. It was invented about 200 years ago by a mathematician and astrologer.

It was never meant to be used as a definition of health. It was meant for sort of statistical purposes. And somehow it's ended up being this indicator of whether somebody falls into a certain weight category or not, and therefore how we interpret their overall health. Which for a long time, there's been a lot of debate that this isn't an accurate way to do this. It ignores a lot of things. I have done a previous podcast all about BMI, and this is not where I'm going today.

Just to recap slightly about the inaccuracy of BMI. Firstly, it doesn't take into account the difference between muscle and fat. It's purely your height in relation to your weight. So it doesn't take into account someone that may be all muscle that's making up that amount of weight or all fat that's making up that amount of weight. It has no way to distinguish between the two. It also doesn't take into account age because people generally lose muscle mass as they get older.

So BMI is just this blanket response to height versus weight, doesn't take age into account, doesn't take gender into account. Originally, the whole premise of it was based on European white men, and it might not be accurate. In fact, we know it's not accurate for other races, other ethnicities. It also doesn't take into account the fitness level or the activity level of that person.

So, for instance, a lot of athletes have very, very high muscle mass and may actually, using the BMA scale, appear to be in the obese category, but they're all muscle. And also, it doesn't take into account fat distribution. So, where the fat is on the body makes a big, big difference to how it affects our risks of disease. So, that's a little bit of a recap on what we know is wrong.

And we've known this for a long while. But the question has always been, how can we do this if we don't rely solely on BMI? And that's where there's been this lack of any other ideas, any other good ideas that are actually usable in how we would diagnose something like obesity and how we would then move forward with treatment of that if we can't distinguish other than BMI who falls into that category. So there has been a new study conducted, and it's taken quite a while, actually.

It's been done by the Lancet, and I'm just trying to find out what it's called. Okay, there was a committee or a commission, which was the Lancet Diabetes and Endocrinology Commission on the Definition and Diagnosis of Clinical Obesity. And what they did for this, it was led by King's College London, and they were. And they brought together 56 experts on aspects of obesity, including people with lived experience.

So this wasn't just a group of academics in a room hypothesizing on what this should be. They actually included people who were living in larger bodies and asked their opinions as well. And I know there are a number of these academics from Australia, because I do know some of them personally and have met them through my work with an organisation called ANSMOS.

And people like Professor John Dixon, Wendy Brown, they were part of this committee that were involved in the organisation of redefining this. And it's taken them, I think, three years.

Yes, the commission was established in 2022 and they eventually published the results of it just last month, January the 15th, 2025. So what they knew when they went into this was BMI does not alone tell us whether a person has health problems related to excess body fat. People with excess body fat don't always have a BMI of over 30, meaning that they actually kind of are left out. They're not investigated for health problems that might be associated with excess body fat.

So in other words, it's not an ideal solution. It also might occur that they have a very tall person or someone who tends to store body fat in the abdomen, but who's actually of what they would define as a healthy weight. So there's these kind of people that slip through the system, these little loopholes, if you like. So the new definition has been split into two categories. They're now categorizing category one as clinical obesity.

So what they're suggesting is this is a person who has signs and symptoms of ongoing organ dysfunction and or difficulty with day-to-day activities of daily living, such as bathing, going to the toilet, dressing. So what they're saying is there's either medical evidence there that something is going wrong on a physical level, or that somebody's body fat is affecting how they function in their day-to-day activities. So this isn't just about, you are a certain weight, therefore you must be obese.

This is more, is that weight affecting you, either medically or physically? And there's 18 diagnostic criteria for this clinical obesity, and there's 13 diagnostic criteria in children and adolescents. So they include things like breathlessness caused by the effect of the fat surrounding the lungs, or obesity-induced heart failure. So in other words, the level of fat is affecting the cardiac function.

Raised blood pressure, hypertension, fatty liver disease, abnormalities in bones and joints that limit movement in children. So even though in a child they might not have those advanced symptoms that we might see in adults, the fact that they can't move their bodies in the same way as would be ideal is one of the the new considerations.

And they're suggesting a factor two or a level two, which is called preclinical obesity. So a person with preclinical obesity has high levels of body fat, but that's not actually causing them any illness at that time. So people with preclinical obesity do not have any evidence of reduced tissue or organ function due to that high level of fat that they're carrying. And they can complete day-to-day activities unhindered.

And this has been an argument for a long time where people say, you can be fat and fit. And there's been lots of people, I've seen many, many lengthy arguments on the internet, which always leave me so frustrated because you kind of, you hear both sides of the argument, but there's lots of people just arguing from either their personal experience or what they've been told or what they've seen in the media.

And quite often they don't have lived experience and they don't have actually any medical knowledge either. So this idea that you can be carrying extra fat, you can be in a larger body, and it actually not affects you. Therefore, there's no reason for you to be diagnosed or assessed as being clinically obese.

And that, I think is a really good observation and justification for those people out there arguing that indeed you can carry fat and it really not affect you in any way in your day-to-day life.

So what does this mean for treatment going forward? Because we know if someone is categorized as obese, which at the moment, because these changes haven't applied yet, at the moment, a BMI of over 30 would put you into the obese category, according to your GP. And at the moment, that means that your GP can explore certain. Options for you for treatment for that obesity.

So what might change in the future is obviously the way that the GP can recognize or categorize somebody that comes to see them, and it will also affect the options that are offered to that person. Should we then, the big question is, people who fall into what will be the new clinically obese category will presumably have a lot of options open to them. That might include surgery, that might include medications, that might include, I suppose, a more traditional diet and exercise approach.

The options that we see at the moment that are offered by your GP as standard. But what about those people who don't fall into that clinical obesity category anymore. So if someone goes to their GP and actually there's no evidence of anything being wrong with them physically and causing any sort of metabolic imbalances, and also there's no evidence of any physical limitations on that person, what should we be offering those people?

This is where it's going to get interesting because in a lot of other health issues, we look at prevention being better than cure. So if we can prevent someone from getting diabetes, for instance. That's far better than someone having diabetes and then us trying to treat it.

So in theory, if someone presents to their doctor in a preclinical obesity state, so reminder that somebody who has high levels of body fat, but it's not affecting them medically or physically, the argument would still be surely that your doctor should intervene.

And then we're back where we started because I know at the moment a lot of people who are in that position where they're in a bigger body, but metabolically, they're absolutely fine and physically they're fit and active, they don't want the GP to be calling them out on their weight when they've just been to the GP for something that's completely and utterly irrelevant to their weight. So I do wonder...

Is this actually really going to achieve much? You know, we know BMI is rubbish, but is this better? It's better from the point of view that it encompasses more symptoms and it identifies the fact that you can't just say because fat is there, that's the diagnosis. It does take into account the fact that the fat can be there and you not really be having the effects of it in the way that someone else might be.

But that middle ground, that middle ground of someone who presents, they're absolutely fine. They've gone along because they are having a problem with their eye or something. We'll still get the talk about obesity prevention that I presume this whole commission was meant to negate.

But here we are again. So I'll read the bit of the commission report that says what happens next, because it says lots of good stuff, but my doubts are whether this will eventuate. Let me read it first. So it says, what happens next? These new criteria for the diagnosis of clinical obesity will need to be adopted into national and international clinical practice guidelines and a range of obesity strategies. Once adopted, training health professionals and health service managers and

educating the general public will be vital. Okay, agreed. Reframing the narrative of obesity may help eradicate misconceptions that contribute to stigma, including making false assumptions about the health status of people in larger bodies. A better understanding of the biology and health effects of obesity should also mean people in larger bodies are not blamed for their condition.

People with obesity or who have larger bodies should expect personalised, evidence-based assessments and advice free of stigma and free of blame. Which sounds wonderful, doesn't it? I really, really hope this is the catalyst for change. I don't want to be negative about this. I really do see it as a positive move. I think it's well overdue. We've known for a long, long time that BMI was not the way to do things, but there was a lack of an alternative, a viable alternative.

And this seems to be one. The problem, I think, is going to be changing the perception, firstly, of health professionals, but then of the general public. And that's going to take, I don't know how long, decades, maybe. It's not something that all happen overnight. We know there's lots of evidence of papers that I've read that prove there's a lot of white stigma that patients experience within the health system.

I agree we've absolutely got to fix that first because if the health professionals can't do a good job and can't understand the mechanism of obesity and weight gain and understand that we need to offer a more personalized and sometimes quite a complex response rather than just eat less and exercise more, then what possible hope do we have of convincing the general public about this?

I do sometimes wish this was a talkback situation where I could actually field other people's opinions and have you call in somehow and tell me how you feel about this, because I would be really, really interested to hear. I'm sure it's going to be an ongoing debate and it's going to come up in a few areas of the media, how we treat this, and especially if it gets to a stage where it is implemented as the new guidelines.

And I'm sure at the next conference I go to, there might be a lot of talk around it as well because it is quite interesting. I am positive about it. I do think it's a good move. It has to be to get away from BMI.

The only dampener on my enthusiasm, I suppose, is going to be the knowledge of the amount of stigma that's out there that is focused on people in larger bodies and the amount of real momentum it will take to be able to budge that stigma and budge people's perceptions when in a lot of people they've been established for so long. We've got a real huge amount of work ahead.

But hopefully, we will get there. Maybe not in my lifetime, but for the next generation of people, maybe things will be different in the future. I don't know, but I can only hope so.

Now, looking forward, let's be positive, looking forward to next week. And I have got one hell of a guest next week. This is going to be a good one. I'm going to get to talk to Michael Collins, and we will be discussing sugar addiction. Now, I recommend you to Google Michael Collins before next week, because he is a gentleman who's lived sugar-free for the last 30 years. So, well before the modern day influencers and YouTubers and other people that talk about this. He was a bit of a pioneer.

So I'm really looking forward to chatting to him. I've seen him interviewed on other platforms and he's really interesting to talk to. So we should have a lot of fun next week. Please join me again and perhaps tell your friends to join us as well because we would love to have more people listening out there. Speak soon.

Don't forget to check the links in the episode notes to our six-week Change Your Relationship with Food course and to the Change Your Relationship with Food workbook and journal, which is available on Amazon. Music.