To think it’s time to scrap the concept of BMI?

[AnyoneWhoHasAHeart]

There’s a lot of talk these days about the obesity crisis, and what a healthy weight should be. And I totally agree that we absolutely are in a place where obesity is definitely a thing.

However, there seems to be very little talk about what is at the other end of the scale, and being. Underweight seems to be a trend people want to aspire to.

I calculated my BMI this morning, and it told me I have a BMI of 21.

I’ve just spent four months in hospital, have had major surgery, and lost an astronomical amount of weight. I wasn’t overweight to begin with, but I am 5ft 2, and I currently weigh 44kg. I don’t need to be told I need to gain some weight at least, and I am trying, but I’ve lost my appetite so that’s a process.

But calculating my BMI this morning it said that my BMI is 21, which is almost at the upper end of the scale, however it then goes on to say that a healthy weight for my stats is between 47/60kg. So how exactly does that follow?

If you’re looking at BMI only you could be forgiven for thinking that 44kg is a healthy weight, when trust me it really isn’t at this point.

So how many people are being told they’re obese based on these types of calculations where actually, they’re probably not?

We Need to start looking at weight not BMI, because it’s just not accurate.

my BMI is 21, which is almost at the upper end of the scale,

The upper end of healthy is 25.

Your BMI is 17.7 and you are underweight.

I don’t disagree with you, but you have made a mistake calculating your BMI.

I am 4'10 and a similar weight and my bmi is 21 , I'm sure you've miscalculated

21 is NOT at the upper end

25 to 29 is considered overweight

30 to 39 is obese

40 is morbidly obese

This is for 'normal' people

Anyone who suffers from any congenital condition affecting height, weight and metabolism, anyone who hasn't finished puberty and any elite athletes with very low body fat levels, but lots of muscle cannot have the BMI scale applied to them

For the vast majority of us, the BMI scale is fine

yes comes out at 17.7 - I think you must have calculated wrongly

I mean I don’t love the BMI system but your have miscalculated here, it’s a blunt tool for sure but you need to redo your maths.

I have a BMI of 22 at 64kg which is in the upper section of the healthy range. You are 20kg lighter there is no way of you sitting at the same level.

oh I’m fully aware I’m underweight, that’s why I put the stats into an online BMI calculator and was shocked with what it came out with.

The weight thing is a definite process. Currently I seem incapable of gaining any so am having to work on that. It will happen it’s just a matter of time and also rebuilding some muscle tone.

It just got me thinking was all.

You've made a mistake lol. Both in calculating yours, and assuming 21 is at the upper end. It isn't.

BMI is a great rough guide that works. The healthy range for most people is actually massive. At my height it's about 40lb between the lower threshold and upper. I tend to think people who criticise the BMI either don't understand it, or aren't happy with being told they're overweight.

Just for reference, I didn’t calculate it manually, I used an online calculator.

So if I’m getting wrong calculations off the online calculators, then others will be as well..

oh I’m fully aware I’m underweight, that’s why I put the stats into an online BMI calculator and was shocked with what it came out with.

No, your BMI is 17.7, not 21. So you don't need to be shocked - you're underweight, the BMI calculator told you you were, so clearly it's working as intended.
Where does the 21 business come from?

You are underweight, have been poorly, lost weight as part of illness and have a low BMI.

None of that is a reason to not use the upper limit to explain to people that their weight is creeping over what it should be for their height.

I don't doubt that there may be better ways of looking at weight and it's health implications but right now BMI does do that.

We are at a stage where being overweight is absolutely normalised and there are lots of psychosocial reasons for it all but it doesn't change the basic fact that increased BMI is associated with greater risks to your health - diabetes, cardiovascular disease and joint problems.

So if I’m getting wrong calculations off the online calculators, then others will be as well..

Nope, perfectly accurate. You've done something wrong.

https://extras.bhf.org.uk/patientinfo/bmi-v1.01/app/index.html

Your BMI is 17.7 not 21. 47kg would give you a BMI of 19 and a healthy weight at the low end.

Which calculator? It’s a simple equation, they shouldn’t be getting it wrong.
and you’re definitely being unreasonable to describe even the erroneous 21 as ‘near the upper end’ - the healthy range is 18.5 to 25, midpoint 21.75 .

It's extremely unlikely the actual calculator is wrong. It will be the information you have given it.

So you used a broken calculator or put the wrong numbers in by accident and now think the entire concept of BMI needs scrapping?! Er... ok.

You've definitely gone wrong somewhere, my BMI is 21 when I'm an inch shorter and weigh more like 50kg.

I think it is a useful tool for the majority, it gives a good indication of if you are a healthy weight. Obviously it doesn't account for your own preference, I can be a high normal BMI but think I look better at the lower end but that's fine, the lower end of normal is still normal.

BMI is not designed to replace common sense.

Do we really expect any system to remove all responsibility for ourselves?

You have used common sense to identify that your (mistaken) BMI is not healthy, and presumably/ hopefully you have some ongoing support from hcp to continue to get healthy.

Elite athletes and weightlifters who don’t fit the BMI model will also have an informed perspective.

BMI is a good indicator in the majority of cases. Weight alone is not helpful because of the height factor.

You can get smart scales that measure fat / muscle % if you want more refinement.

Sorry you have been so ill OP, and I hope your convalescence and recovery go well.

Which calculator did you use OP? Can you link?

BMI is a good system for the vast majority of people (except professional rugby players etc).

Yeah, it's just that either you've made a mistake or the website glitched. BMI works as a guide for most people and the online calculators are usually accurate.

Hope you feel better soon.

I was at the bottom end of “ healthy” for a long time but had a number of health issues that resolved when I moved up the healthy bmi window. I’m not a large build skeleton-wise. I just think it wasn’t right for me.

Otoh I don’t disagree that anyone aiming for underweight or nearly so is probably being foolish, especially if they’re older. There’s a suggestion that for over 65s a range of 23 to 32 may be more appropriate - there’s some info in this short thread

https://www.mumsnet.com/talk/weight-loss-injections/5318615-bmi-table-age-65-plus

Not a perfect system for sure but how on earth would just looking at weight improve things? A 12 stone woman height 4ft 11 vs a 12 stone woman height 5ft 11 have very different body shapes and likely fat levels.

It's a good rough guide for people I can't imagine it'll ever not be used