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About BMI

(15 Posts)
Home77 Fri 22-Mar-19 17:34:50

I'm surprised people still seem to think BMI is such an important measure of fitness. It's quite outdated. Especially when they use it to 'prove' they are in fact somehow better than others not of an 'ideal BMI' - weight shaming I suppose.

It's an old fashioned measure and here is a good description of how it can be misleading.

www.medicalnewstoday.com/articles/265215.php

www.nytimes.com/interactive/projects/cp/summer-of-science-2015/latest/how-often-is-bmi-misleading

TheMightyToosh Fri 22-Mar-19 17:39:33

In a professional situation it wouldn't be used in isolation to gauge 'fitness', and if high BMI was obviously down to muscle weight rather than fat, that would be taken into account.

ZippyBungleandGeorge Fri 22-Mar-19 17:40:17

I think everyone knows the flaws in BMI but as s rough guide it's ok. I think most people who are over weight know they are really.

Stargazer888 Fri 22-Mar-19 17:48:38

I think BMI does a good job of being applicable to the majority of people. There are always exceptions but it is a large range or healthy that it includes. For my height the range is 105-140. That's a pretty large range of normal.

FlirtyRomanticToast Fri 22-Mar-19 18:47:45

The fact that the 'healthy' zone does cover such a wide range is an indication of how imperfect (or approximate) the BMI system is. The range is often around 3 stone. So a person who is 5ft 7" could roughly weigh between 8.5 and 11.5 stone and remain in the 'healthy' zone.

sar302 Fri 22-Mar-19 21:19:05

When I was at the upper range of "healthy" BMI, I was fit, quite muscular, and looked good. I'm now just tipping into the "obese" range post child birth and some physical health issues. And I am fat and out of shape. For me, the numbers (sadly) do not lie!

Happyspud Fri 22-Mar-19 21:21:51

Why would you find it so important to discredit it? It’s just a general guide and I actually think that if you keep your body within the healthy range, you’re certainly doing no harm.

kmc1111 Fri 22-Mar-19 21:37:26

It’s a good general guide. It’s not perfect on an individual level, but it’s a good barometer for most of the population.

If you’re particularly short or tall or an athlete/bodybuilder or so on, then it doesn’t work very well. But let’s be honest, the people who complain about its innaccuracy are very rarely 4’9 or carrying an extra 50lbs of muscle etc. It’s almost always people who thought they were an ok weight, maybe just a little chubby, and really don’t like being told their BMI puts them in the obese category.

eurochick Fri 22-Mar-19 21:43:36

It's a useful guide. Even the source you cite only has it inaccurate 18% of the time (if you accept their 25/35% body fat assumption is a useful guide). That means it's a good guide 82% of the time.

I agree with the poster who mentioned that those trying to discredit bmi are not typically the extreme athletes with unusual body compositions...

lljkk Fri 22-Mar-19 21:56:48

I like BMI. I would call it useful rather than 'important'.

From one of OP's links: "There is an urgent need for accurate, practical and affordable tools to measure fat and skeletal muscle, and biomarkers that can better predict the risks of diseases and mortality. "
Those types of measures cost a lot of money (to measure & record, and they don't have decades of data to compare with). Maybe more accurate but not nearly so useful. Plus all you would do with all that data is feed it into a risk score tool with wide uncertainty values. There would still be plenty outlier (people) whose health was not well predicted by the models.

AnnaMagnani Fri 22-Mar-19 22:05:36

It's a good general guide and when people calculate it on themselves, it is a lot more accurate than dress size or other things that lull people into a false sense of security.

I know I had a nasty shock when I found out I was obese on the BMI scale - everyone around me helpfully said 'but you aren't that big', um but I was, we'd all just normalized it.

Someone will always come on and say that you can have an obese BMI and it all be muscle like a rugby player - but I hope that those who are elite athletes know who they are and that everyone else is just kidding themselves.

SlackerMum1 Fri 22-Mar-19 22:09:02

It’s a population based measure, so of course it’s not 100% accurate for every individual. It’s a decent enough guide though for most people. I’d agree in general the people going on about how it’s inaccurate and how rugby players are technically obese are general deflecting... unless you train 5 hours a day as a professional athlete, if your BMI is obese you might want to think about that.

Fozzleyplum Fri 22-Mar-19 22:16:58

There are regular threads on MN about BMI.As a pp has said, someone will always come on and start talking about elite athletes being classed as obese, but we all know that applies only to genuine outliers, not non-athletic types who are trying to kid themselves.

If we are all honest about our real height and weight, the vast majority of people who are outside the (generous) range of healthy BMI could do with gaining or losing weight for health reasons.

We are used to vanity sizing and the average female size nowadays being a 16, but average and advisable are not the same thing.

Footloose80 Sun 24-Mar-19 09:31:39

I rather like a Swiss model BMI emwhich is used on the smart VMI site. If makes allowances for age and adjust categories accordingly.

Footloose80 Sun 24-Mar-19 09:32:38

Bmi which Bmi.

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