What is the Body Mass Index and is it the best measure of obesity?

What is the Body Mass Index and is it the best measure of obesity? - CrowdScience, BBC World Service

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Күн бұрын

CrowdScience listener Maik wants to know what the Body Mass Index is and what his BMI score says about his body.
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Maik trains dogs for a living and wonders if, like different breeds of dog, we simply have different body types?
So, Marnie Chesterton comes up with some answers, talking to doctors about how the BMI is used and misused in clinical practice, and looks at some alternative methods for measuring our body composition. She also sits down with philosopher Kate Manne to discuss the realities of living in a fatphobic world.
We hear from Tonga in the South Pacific, where high BMI scores have labelled the country highly obese. But this is not necessarily how Tongans see themselves.
And Marnie finds out if the BMI will continue to be used across the world as an important health marker to say whether people are healthy, overweight or obese, or whether it is destined for the scrap heap of medical history.
Watch more episodes of CrowdScience here 👉🏽 • CrowdScience
00:00 How to calculate BMI
01:20 Listener Maik wants to know what BMI can tell you about your health?
02:20 How the WHO uses BMI to classify weight
03:05 History of BMI and its inventor
04:15 What the BMI tell us and why excess fat can be bad for our health
06:40 What other kinds of health screening are there? Marnie enters the BodPod
11:35 What Tongans think about their weight and the BMI
16:04 How useful is the BMI?
17:20 BMI and access to health care
19:10 Weight stigma, or fatphobia, and the BMI's role
21:40 The BMI classifications were changed in the late 1990s
24:14 Should we stop using BMI?
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Пікірлер: 66

@Pou1gie1 16 күн бұрын

@14:00 In Tonga, and with many colonized countries, the issue is that they aren't eating their traditional native foods anymore. I have heard stories of native Alaskan ppl being sick on western foods going back to their native foods and after months to years they no longer have diabetes, high blood pressure, etc.

@ravindra7791 15 күн бұрын

Yes... specifically I understand Australia (and NZ) have sent low cost meats of cuts that they don't eat to the Pacific islands. So that is a cause too.

@shyft09 14 күн бұрын

the trouble is modern western foods are more delicious (salt, fat , sugar, msg etc) and cheaper to produce

@dinimueter539 15 күн бұрын

I think the BMI is a fairly good guideline for most people. It’s not perfect of course but I don’t get some of the criticism. Come on, everyone knows if they are more the type „bodybuilder“ or „couch potato“. And your doctor can see it. Serena Williams knows she’s not overweight but very muscular. I don’t like how the guy from Tonga sugarcoats Tonga‘s high obesity rate. There’s a difference between larger build and obesity. In Tonga 13% of the people aged 20-79 have diabetes type 2. I watched a documentary about Nauru and how the obesity rate of its population skyrocketed after industrialized countries ruined their environment and started to supply them with cheap ultra processed foods. We need to address this issues instead of sugarcoating obesity. If you want to help marginalized people you need to find out why they are obese instead of claiming that by addressing the issue you are being racist.

@LarryDiamond-te3yt 13 күн бұрын

2:12 one of the biggest issues is this: ‘my neighbors can eat what they want’ and they are thin. At minimum 50% of people, that are ‘normal’ BMI are significantly insulin resistant if not raging type 2. We each have a ‘personal fat threshold’. Someone can have a BMI of 40 and less visceral or organ fat than someone with a 23 BMI. TOFI. Thin outside, fat inside. But there is no health at every size. Too much adiposity even in safe subcutaneous fat, creates chronic inflammation. So it’s the case in today’s world that many ‘normal’ BMI are as obese as the rest of us that can actually get obese. I did reverse my morbid obesity. Noting fancy: tasty real food, intermittent fasting, falling in love with natural fat and salt. Not sexy, super effective. But don’t chase weight loss. I was interested In health. When I found out I could eat steaks and broccoli lathered in butter, my success was assured: Focus on transforming relationship with food, getting healthy, move better, sleep better, fast better. The weight loss follows 🥰🌞🥰

@timosnieder4637 12 күн бұрын

I agree. Focus on health and wellbeing, not weight loss.

@petervince167 17 күн бұрын

I think waist-to-height and waist-to-hip ratios are better predictors of obesity risks. Clinical tests such as complete blood count, blood pressure, and other tests are more useful than bmi and the ratios mentioned above.

@marathorne6821 8 күн бұрын

It's a "cheap and cheerful" measure. Body fat composition is not accessible to everybody at home. Too much fat, particularly visceral fat, compromises health. BMI is far from perfect, but it's a starting point for further investigation.

@stuartneil8682 15 күн бұрын

So at just over 6’ and 75kg I look skinny but have non alcoholic fatty liver disease. This despite running and some weights and feeling healthy at age 62. When In was slightly overweight according to BMI then the last time at 85kg it was less excercise and more biscuits, however I’ve been that with earlier in life with consistent work in the gym so it illustrates the points that you are making, that it’s a poor measure of my health.

@now4itfriends 16 күн бұрын

Thank you so much, this was an excellent overview 👌🏻

@BartBVanBockstaele 16 күн бұрын

As the video says: BMI is not and was never meant to be a measurement of health. Anyone who does that anyway, does not really know what he/she is doing. As is popular in computers: RTFM. That is always good advice.

@YPNOBATHS 7 күн бұрын

I was 102 kilos and with health of my dietician I reach my normal BMI . It's important to understand that you should be educated by career how to combinate the food. There's no meaning to be slim and to eat harmful products . Or your goals are only to lose your weight.

@gergohavasi7902 8 күн бұрын

I think it's another way not to take responsibility for our choices and actions. I especially dislike the argument that bodies come every shape size. Historically humans never had constant access to this amount of food. Preserving fat was a tool to survive famine, which occured regularly. Now it's on us to say no to excess food, as our body is not smart enough to do so

@campflint76 16 күн бұрын

We know that visceral fat is the real problem- too much increases the risk of a range of diseases. BMI is a rough but sometimes inaccurate screening tool for excess visceral fat. Not many people can afford an accurate but expensive,say, DEXA scan. That said, by the time one’s BMI is in the obese category, unless you’re a professional bodybuilder, you know you likely have too much visceral fat. No shaming here, just a medical condition to be addressed.

@careylee2595 17 күн бұрын

How about waist hip and waist height ratios?

@laurachristianson1688 13 күн бұрын

This too is problematic as short waisted people’s waist measurement is closely related to their hip measurement, there’s only so much area you can squish your internal organs into….

@mamakaka73 14 күн бұрын

People need to grow a spine. Admit it. You are fat. I am fat. Life is not all rainbows and unicorns.

@asrafuldigital1247 17 күн бұрын

Nice very helpful video i am from India

@1chooOne 16 күн бұрын

There had been so much fuss about BMI so much so that people become obsessed by it. But a low BMI is misleading. A regular consultation with one’s practitioner coupled with full bloodwork will help assess one’s health situation better. I for one has always had a low BMI only to find out my blood markers show otherwise; thin on the outside but “fat” on the inside. I find a regular check with my GP is more beneficial in catching underlying health issues early enough thankfully.

@marathorne6821 8 күн бұрын

The word "diet" is now used to mean some (often faddy, drastic) short-term weight loss intervention that people either can't stick to at all, or cannot wait to revert back to their previous eating patterns - hence their high failure rate. If you adopt a healthy but satisfying eating pattern with a view to sticking with it FOR LIFE, you'll be able to keep the excess weight off once you've lost it. I believe the biggest enemy nowadays is ultra processed food, scientifically designed to encourage over-consumption of unhealthy chemical substances masquerading as food. It's really difficult to avoid consuming this stuff, it's ubiquitous and looks like the real thing (until you read the ingredient labels) but it's worth trying. "Garbage in, garbage out" doesn't just apply to computer programs.

@SkepticalTeacher 11 күн бұрын

FFS, if you have a BMI of 30, you need to lose weight! When I was slim, I was at 25 because I'm at the higher end of BMI... But now I'm at 30 and it's because I weigh over 100 kg which is not healthy!! I think the female presenter is in denial....

@la6640 11 күн бұрын

I think waist should be measured against the hips ratio. Legs and arms are healthly when they are big specially if it's mostly muscle mixed with fat.

@yucalin3000 17 күн бұрын

0:23 Isn’t it weight divided by square meters of height?

@pynn1000 17 күн бұрын

May have been in metres for the original BMI tables, but "cm" are more used for metric measurements of height e.g. all online metric calculators ask for measures of height using "cm".

@shyft09 14 күн бұрын

When it comes to doctors advising their patients to add or loose weight as a result of their BMI number (as they do unfortunately) it can be disastrous for someone who it doesnt apply to. People trust their doctors

@galactic_socialist 15 күн бұрын

Remember Arnold Schwarzenegger had a BMI of 31 during the peak of his bodybuilding career My physician doesn't buy into BMI but has to record it to get payment from the insurance company

@CatholicSatan 14 күн бұрын

Oh yeah, 'cos _so many_ people are elite body builders.... BMI is a good indication for the vast majority of people.

@bk2no 14 күн бұрын

Steroid use will allow you to put on more muscle than the average man. As stated in the video, muscle weighs more than fat. BMI is a good indicator for most normal people. You can also just look in the mirror. If you have a big gut, you’re overweight.

@cassieoz1702 12 күн бұрын

Obesity is overfat, not overweight. Even the use of BMI as an indicator of survival has aggregated all ages when, if you plot BMI by age, what are 'healthy' BMI ranges varies. Slightly higher BMI predicts longer life in over 60s.

@timosnieder4637 12 күн бұрын

Which is a more significant problem: the stigma around being obese, or the obesity itself?

@shyft09 14 күн бұрын

Some countries use WHR and that seems to make much more sense, I think Japan does. Belly fat is a real killer, fat on your thighs (for a woman) is not

@pynn1000 10 сағат бұрын

WHtR (or WSR with S for "Stature") is cheap, simple, works with a simple sum. UK officially adopted it as a better measure than BMI nearly 2 years ago (but I don't know if it's widespread yet). Japanese, other researchers have shown that it works with varied ethnic groups and ages.

@aroundandround 17 күн бұрын

0:24 At least learn what to divide by what.

@garrett7101 15 күн бұрын

Muscle phobic for sure

@user-rw8qt7jf3q 12 күн бұрын

You're fat in your pic lol

@user-we3ep5yq2m 14 күн бұрын

"you ate your way in, you can walk your way out" Bill Burr

@chrisengland5523 17 күн бұрын

BMI doesn't make any sense to me. It would do if it were mass / height cubed rather than squared. Why? Because with the current definition, it is skewed in favour of short people. Here's a hypothetical situation to explain this: Consider two people, one is 1 metre tall and the other is 2 metres tall. Also, and this is a KEY POINT the two people are proportioned exactly the same - in other words, the tall one is a magnified version of the small one. Assume that the short one weighs 20 kg. So let's calculate their BMI's, which is the weight in kg divided by the height in metres, squared. The BMI of the short guy is 20 / (1 x 1) = 20 kg / m2. (A supposedly very healthy value.) To calculate the BMI of the tall guy, we need to work out his weight. Remember, he has exactly the same proportions as the short guy, so if he is twice as tall, he's also twice as wide (side to side) and twice as thick (front to back). So his 'volume' will be 2 x 2 x 2 that of the short guy and therefore his weight will be 20 x 2 x 2 x 2 = 160 kg. His BMI is therefore 160 / (2 x 2) = 40 kg / m2. So the tall guy has a BMI twice that of the short guy despite the fact they are both identically proportioned. Why does simply being taller but identically proportioned lead to a higher BMI? An identically proportion person will have all the vital organs and fat etc. in the same proportions as the short guy - yet, the BMI says he's unhealthy. It doesn't make sense.

@swimmerboy172 16 күн бұрын

You are wondering why the person that is 2x as tall but 8x the weight has a higher BMI? Seems kinda self-explanatory

@chrisengland5523 16 күн бұрын

@@swimmerboy172 Yes, that's what the maths tells us, but the point is, it doesn't make sense. Someone who is twice as tall SHOULD weigh 8 times as much otherwise his proportions are wrong: twice as much because he's twice as tall, twice as much again because he's twice as wide (from side to side) and twice as much yet again because he's twice as thick (from front to back). And 2 x 2 x 2 = 8. If he's not 8 times as heavy, his proportions are wrong. Think in terms of a cube, 1 x 1 x 1 metres and assume it weighs 1 kilogram. It's BMI is 1/(1x1) = 1. Now stack 8 of these cubes together to make a larger cube 2 x 2 x 2 metres. This is just a larger cube but apart from that its properties are identical. Everything is in the same proportion, so if it were somehow alive it would be just as healthy, but its BMI is 8/(2x2) = 2, ie. twice that of the single cube. So the question is why is BMI measured as weight/height squared, rather than weight/height cubed? Either whoever invented BMI is hopeless at maths or there's some factor that I (and most others) don't appreciate as to why it's the way it is.

@zlinos139 15 күн бұрын

What!? It makes perfect sense,if you are 2 m tall and 160 kg weight,you are not healthy obviously

@chrisengland5523 14 күн бұрын

@@zlinos139 Your missing the point. It's the RELATIVE figures that count. If it helps, rework the figures with lighter people, starting with the tall guy. Assume that the 2 metre tall guy weighs 80 kg. His BMI is 80 / (2 x 2) = 20, which is a healthy figure. Now scale him down to 1 metre in height to get an identically proportioned short guy. The short guy will weigh 80 / 8 = 10 kg and his BMI will be 10 / (1 x 1) = 10, which is far too low. Why? He has the exact same proportions as the tall guy and his weight is in the same proportion, but the BMI calculation leads to absurd figures.

@zlinos139 14 күн бұрын

@@chrisengland5523 Are you saying that in your calculations a person weighs 10kg and you want me to take your comment seriously?

@Lovely-DeeM 12 күн бұрын

BMI is a very flawed measure of anything, there was a pastor in the church I go to, who once stood on the pulpit (he is pretty tall and lanky and middle aged, so no muscles or athletic body to say that the BMI calculation took his muscle mass as fat), and the BMI calculation stated that he was obese which is ridiculous. He was joking about it on the pulpit. Ever since then, I realized that the BMI measurement is not accurate at all, and should not be used in any medical institution to determine obesity.

@jovsta 15 күн бұрын

1.9m is 6 foot 3.

@JanetLClark 17 күн бұрын

Ugh Ansel Keyes, champion of cereals :p

@yongbinsong9676 17 күн бұрын

BMI is not proper to identify the degree of health.

@pynn1000 17 күн бұрын

Useful at a large level to see changes within a population, or (with caveats) to compare countries. I agree that it doesn't tell us much about individual health.

@timosnieder4637 12 күн бұрын

I dont think that was ever its goal, as per the host.

@BBCWorldService 17 күн бұрын

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@Pietro-th1yd 17 күн бұрын

As far as I know, dieting has a high failure rate because, often, it is practised without the aid of a professional...

@laurelledubois 17 күн бұрын

The vast majority of them haven't got a clue themselves. Failure is due to wrong eating patterns/no willpower and our hormones failing us.... The problem is: if the right eating habits are not taught at home from childhood, it it very hard to un-learn them in adult life... Also most people haven't got a clue what "healthy eating" actually means...

@Pietro-th1yd 17 күн бұрын

So you seem to agree with me on the fact that this episode send a wrong message about dieting.

@BartBVanBockstaele 16 күн бұрын

Not just that. It is also a matter of self-knowledge. I have struggled with my weight for over 40 years. Nothing worked... until I accidently found a way of eating that made it possible to be **less** hungry. Willpower did and does the rest. As a result, I lost well over 60 kg and am keeping them off.

@Pietro-th1yd 16 күн бұрын

The wrong message this episode conveys is that because of its high rate of failure dieting is not a reliable method to control your weight. I'm there a more people who quit the gym rather than people who keep up exercising, however, working out is undisputably beneficial...

@BartBVanBockstaele 16 күн бұрын

@@Pietro-th1yd I wholeheartedly agree. Just because people don't do A is a nonsensical reason to say that A doesn't work.