If BMI is so outdated what should be used instead?

[AutisticLegoLover]

Inspired by another thread where some posters are slating BMI as outdated.
BMI is a blunt tool, I agree, but what should be used instead? The old height weight charts were devised by American insurance companies or so I read in an eating disorders book. BMI was devised by analysing white European men. It's not possible to have everyone measured by callipers so what should be used? I personally think BMI is very generous and has a large range of healthy weight for height. 18.5-24.9 has a range of something like 3.5 stone for me but as a guide it's useful and ideally should be used alongside blood pressure and cholesterol and waist measurement. Not everyone can access BP and cholesterol checks easily though.
I am a retired GP Practice nurse and we used BMI but also had a height and weight chart on the wall. The height and weight charts are less generous. Still, it's just a blunt tool, a guide, an easy starting point.

What should be used instead to be more accurate for the whole adult population?

BMI is still very useful. It’s just to be used with caution on people like weight lifters or athletes.

What is perhaps even more useful is the waist to hip ratio, or just waistline in general. Apple shapes have a higher risk of metabolic syndrome and other things.

So it’s not that BMI is useless, it’s just that we are getting better and more refined, so it’s just use as a guide with other measures.

I am just over healthy in BMI - and unfortunately for me, that’s pretty accurate and I do need to get into the healthy BMI zone so it’s very useful for me. I’d like to pretend it’s muscle… but no!

As someone with J cup breasts which must weight a good couple of stone, I agree. Seems very unfair they're included as they've never gone up or down since puberty, whatever weight I've been (apart from during breastfeeding when they were even larger!)

Even with high-level athletes, the only sports in which it's relevant are sports in which you need big amounts of muscle mass.

Professional marathon runners, gymnasts: BMI still relevant, because these sports don't rely on lots of muscle mass.
Professional weightlifters, hammer throwers, rugby props: BMI less likely to be accurate.

Waist / height ratio is good https://www.omnicalculator.com/health/waist-height-ratio#:~:text=What%20is%20a%20good%20waist,related%20to%20excess%20body%20weight.

VO2 Max is decent - Apple watches and most wearables do this measurement.

The thing is, if your BMI is out of the healthy range, then it is 99% likely that it will be out of the range of healthy on these measures too so you may as well just stick to BMI. BMI is just a marker - you should never take one measure in isolation anyway and maybe that is what people react to. If you could say "I have a BMI of 29 but my VO2 Max is 40 so I know I am fit and doing ok" then all would be fine. But if it is "My BMI is 29 and my VO2Max is 20" then Houston, we have a problem, and an undeniable one too.

I love the Omni calculators!

Slightly obsessed / hypochondriac 😳

I think BMI is pretty useful for the vast majority of the population and the ones who don’t like it are never the extremely muscular ones but the ones who don’t like the answer it gives them (Ie that they’re more overweight than they’d like to think)
I agree with this too.

The range for healthy is very generous and accounts for different frames. Some people look and feel their best at the lower end of the range, others in the middle, and others towards the top. Some people with smaller frames would look overweight towards the top of the range, and people with broader frames would look skinny at the bottom end. BMI allows for this.

I'm in fitness communities and have never seen or heard athletic people complain about how awful BMI is. If they're on a bulking up diet and training weights to bulk up, they don't have the physique that means they're worried about having a BMI of 28.

As a proud card-carrying fat activist, I agree that BMI is a blunt tool. I do not have an issue with my weight being used when appropriate e.g for surgery.

I am not sure what the answer is on an already crumbling NHS system - they certainly do not have the resource to start looking at a patient's overall health and fitness. I am the fattest in my company but I have a far healthier lifestyle - they all drink, smoke, eat loads of processed food. Their weight being in the 'normal' BMI shouldn't be what automatically makes them healthier than me.

The BMI scale wasn't intended to be used on individual basis and even the creator said the scale shouldn't be used in medical assessment. Its a rating scale for a mass population that was based on a tiny sample of 100 countrymen in the 1850s. Its irresponsible for the NHS to be using it at all.

@Wyndam what should be used instead?

I think the possibilities of AI are what are interesting here

What is your family history?
What previous health issues have you had?
What's your diet like?
What are your stress levels?
How is your mental health?
What exercise are you doing?
Do you smoke? Drink? Take drugs?

The possibility of AI being able to combine all this information and then be able to more accurately diagnose and predict health issues are incredible. A GP just does not have the time nor the resources/records to be able to review and work like that. Imagine a computer could pull together all the relevant illnesses in my family, combined with symptoms I had suffered with, and tell me what I could be at risk from?

All BMI does is tell you whether weight MAY be a contributing factor to an illness.

Per BMI I'm 27, so I'm actually overweight. Now, I know I'm not stick thin, but I'm a size XS/6-8 so, and if I lose the pounds it wants me to lose I think I'd definitely look a lot thinner.

That’s not true. Several research studies have looked at the link with BMI and adverse health outcomes or surgery etc. It’s that which gives it some credibility. Now that we know more additional measurements are also used, but BMI is still used because it has some validity but this is much stronger with other measures.

It’s a tool, not the only tool and what works at a population level won’t capture each individual.

I’m on a diet and I’ve gone from BMI 28 to 25.3 by losing 1 stone. But I rely on the mirror test- I stand naked in front of the mirror and I still look flabby, probably because I have a high body fat %, am
an apple shape and I have a small build so 25 BMI isn’t healthy FOR ME- but that’s not to say it isn’t for someone else. I don’t take mortal offence at it.

In real life the only people I know who moan about BMI are those who are overweight/obese but don’t see themselves as it. Which I can appreciate if everyone around you is the same size, it feels normal.

Perhaps thats because those in bigger bodies have to deal with medical bias, discrimination, and judgement everywhere they turn.

String test:
What it is: A fun way of measuring your waist-to-height ratio. If your waist is less than half of your height, you're healthy.
Does it work? Yes. A 2014 UK study in the journal BMC Medicine found that the waist-to-height ratio is more accurate than BMI and would account for those people who were "missed" by BMI screenings. Researchers say that it's cheap, easy, and can be used for every ethnic group.

Or my favourite:
US Navy Calculator – Body Fat Calculator. This Body Fat Navy Calculator uses the U.S. Navy fitness formula to get an estimated measuring of body fat percent. Use a tape measure then enter your waist, hip, and neck measurements.
Combine these measurements with your gender and height and this navy calculator will estimate body fat percent, lean mass, fat mass, and your general navy fitness category.
The water displacement test is the most accurate way to determine body fat percent, but the Navy Body Fat test or YMCA formula is accurate within 1-3% for most people.
https://www.bizcalcs.com/body-fat-navy/

I think I read that there was a slightly tweaked version of BMI which better took height into account, the upshot being I think that it gave a bit more grace to very tall people. The issue I can see with BMI is that it doesn’t pick up the “skinny fat” people, those who are within the healthy weight range but carrying all their fat round their middle - so should be used in combination with waist/height ratio.

My BMI: 29
My Navy fitness: Body Fat 17 %
Fat Mass 34 lbs
Lean Mass 166 lbs
Body Fat Category Fit

Thats interesting.

It again only really focuses on fat on a body rather than overall health. When my waist was the smallest I was the unhealthiest I had ever been.

Any kind of tool that uses just one measurement (aka size of body) is only ever going to give a rough snapshot.

Any kind of tool that uses just one measurement (aka size of body) is only ever going to give a rough snapshot.

Agreed, but the question was whats better than BMI, answer - almost anything

Agree with this 100%. You see it all the time. BMI measurement comes out as obese and they start saying "well according to BMI body builders are obese!". Are you a body builder Janice? No.

I also think the measurements are pretty generous. I've been at the top end of a healthy BMI and I felt I looked a bit chubby.

I think for your average person BMI is fine. Body fat % is probably a better way to determine whether someone is a healthy weight or not, but accuracy of body fat scales varies.

I think BMI is not great because it offers too wide a range of what is healthy.

I am just squeaking into healthy weight zone, but I can see just by looking in the mirror I am overweight. I am 10 stone at 5 foot 3. According to one of the other calculators posted here I should be about 9 stone 1. Which is probably about right, but rather depressing.

BMI has been revalorised many times since first devised, so it's historic origin isn't really important when looking at its utility now.

The ranges are wide because it is intended for global use, and body frames vary considerably. The women's one also allows for breast size.

The only times it's not reliable is when someone has exceptionally great muscle mass - so it's certain categories of elite sportspeople and occupations such as the military (but despite that the British military continue to use it, because it provides the pool of people who are prima facie too heavy and need to be individually assessed).

It's a screening, not a diagnostic tool.

It's unpopular because people don't like being told they're overweight, when they think they "look fine" and no health conditions have yet emerged.