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BMI calculations...
TrevorMcC85
Posts: 9 Member
Hi everyone,
This has probably already been discussed but I would like to ask those in the know if BMI calculations are accurate?
I have read a few articles recently that speak negatively about them, even going as far to say that they are completely pointless.
I'm just starting out trying to get fit and healthy and am wondering is it a good measurement of where I am and where I would like to be?
Any help would be appreciated!
Trevor
This has probably already been discussed but I would like to ask those in the know if BMI calculations are accurate?
I have read a few articles recently that speak negatively about them, even going as far to say that they are completely pointless.
I'm just starting out trying to get fit and healthy and am wondering is it a good measurement of where I am and where I would like to be?
Any help would be appreciated!
Trevor
1
Replies
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The people for whom it is truly useless know it is useless for them, because they spent years gaining lean mass which makes them a higher BMI at the same bodyfat amount than normal people.
Those people are few and far between though. For everyone else, the healthy BMI range is a good goal to get to when trying to lose weight.25 -
BMI calculations are very accurate, they can pinpoint your BMI with lots of exactitude. What's not very exact here is what that means. Bigger people have higher BMI numbers and smaller people have smaller numbers; the great controversy is whether people with high BMIs are all muscular demigods, or if any of them might be fat too.10
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I believe they are accurate for 95% of the population. Lots of people don't "think" it applies to them, but usually it does...unless you have a very low body fat percentage and are very muscular.
When I was 5'11 and topped the scales at 193, I was convinced I wasn't that "big", 27 Overweight BMI, yeah whatever. I was tall, proportionate and big boned. Then I lost weight. Got to 143 at one point. A size 16 US to a size 4 US. Trust me, I was "THAT" big...LOL13 -
stevencloser wrote: »The people for whom it is truly useless know it is useless for them, because they spent years gaining lean mass which makes them a higher BMI at the same bodyfat amount than normal people.
Those people are few and far between though. For everyone else, the healthy BMI range is a good goal to get to when trying to lose weight.
This ^^^^^
and..
I use to think it was a crock and that I was a naturally bigger person. Then, I got to my goal weight and realized the BMI chart had me at overweight still and somewhat close to obese. Since then I've lost another 30 lbs and I'm in the "optimal" zone now, but I could even lose another 15 pounds or so no problem. There are people with bigger bones/frames, but that should only account for a very minimal amount of weight and that's why the BMI has different levels within the optimal zone.7 -
TrevorMcC85 wrote: »Hi everyone,
This has probably already been discussed but I would like to ask those in the know if BMI calculations are accurate?
I have read a few articles recently that speak negatively about them, even going as far to say that they are completely pointless.
I'm just starting out trying to get fit and healthy and am wondering is it a good measurement of where I am and where I would like to be?
Any help would be appreciated!
Trevor
@TrevorMcC85 welcome to MFP forums and best of success.
Personally I found BMI calculations a very helpful motivator and it is a read out on my set of bathroom scales. Two years ago my scales and web calculators reported a BMI of 35. As the pounds dropped so did the BMI readout. I remember the day it hit 29.9 so I was no longer classified OBESE by the government guidelines.
At best BMI is a relative measurement without concrete meaning from person to person as to where one has super health or not. My change in my Way Of Eating is to manage my arthritis pain and a side effect has been losing 50 pounds, 40 years of serious IBS and most of my pain. Actually I have developed some muscle without trying. While I do walk at least a 1/4 mile daily with most of my pain gone I do move more and walk faster now as well as being able to get in and out of cars unaided unlike 2 years ago.6 -
It's a good guideline for many and inaccurate for a few - that's how population measures work.
But far too many think they are one of the few!18 -
You might want to check out this thread: http://community.myfitnesspal.com/en/discussion/10438075/how-do-we-judge-a-healthy-weight-range-bmi-is-no-longer-valid#latest
(And what sijomial said.)3 -
It is generally accurate.
During discussions online, anyone who thinks it does not apply to them should have to accompany their post with a photograph of them in their swimwear.15 -
I have yet to see, in my day to day living, scores of The Rock-like beings running around in the general population that reading various threads on BMI would lead me to believe exist in the world today.
In other words, yeah, what sijomial said.6 -
This article explains the stats on bmi accuracy as regards a measurement of over-fatness.
TL;DR BMI is not the best measure of over-fatness and the cut-offs as they are have a tendancy to *under*-detect over-fatness. However, there are health risks of having a high bmi even if you have a low body fat. So, if you have a high bmi losing weight could be good for you regardless of fatness, and you shouldn't lull yourself into a false sense of security if you have a low bmi because you could still be over-fat.
http://evidencebasedfitness.net/lack-of-basic-epidemiology-knowledge-makes-us-all-dumber/6 -
For the majority of the population it is accurate. I notice typically those who scream "BMI is BS" are clearly overweight and in denial about it. For average non-athletes it is pretty accurate.10
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mumblemagic wrote: »This article explains the stats on bmi accuracy as regards a measurement of over-fatness.
TL;DR BMI is not the best measure of over-fatness and the cut-offs as they are have a tendancy to *under*-detect over-fatness. However, there are health risks of having a high bmi even if you have a low body fat. So, if you have a high bmi losing weight could be good for you regardless of fatness, and you shouldn't lull yourself into a false sense of security if you have a low bmi because you could still be over-fat.
http://evidencebasedfitness.net/lack-of-basic-epidemiology-knowledge-makes-us-all-dumber/
Yes, exactly. BMI is inaccurate, but not in the direction people assume. You are more likely to be overfat without being overweight, than to be overweight without being overfat.10 -
I wud rather have a low bmi than big so it's fairly accurate everyones different1
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BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS. There are lots of unhealthy people at a "healthy BMI" and you don't have to look anything like the Rock to be at an overweight or even obese BMI, particularly men. If you want to know if you are healthy, look in the mirror, actually check your body fat, check your blood pressure, check your cholesterol, etc.0
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BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS. There are lots of unhealthy people at a "healthy BMI" and you don't have to look anything like the Rock to be at an overweight or even obese BMI, particularly men.
I'll save you some trouble - this was already hashed out at length in the previous BMI thread here, complete with a few special snowflakes who were convinced that BMI didn't apply to them: http://community.myfitnesspal.com/en/discussion/10438075/how-do-we-judge-a-healthy-weight-range-bmi-is-no-longer-valid#latest13 -
If it makes you feel good to throw around terms like special snowflake to insult people, go right ahead. I have seen the threads. I have seen plenty of people for which BMI absolutely not an accurate measure of health. What I have never seen is BMI take into account body fat or blood pressure or cholesterol or even something as simple as waist size. Heck, a waist size chart would be better than BMI.3
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If it makes you feel good to throw around terms like special snowflake to insult people, go right ahead. I have seen the threads. I have seen plenty of people for which BMI absolutely not an accurate measure of health. What I have never seen is BMI take into account body fat or blood pressure or cholesterol or even something as simple as waist size. Heck, a waist size chart would be better than BMI.
The waist-height calculator is good tool, may very well be better than BMI. That said, there is a little difficulty getting the waist measurement at the right spot. Also, I would assume for 90%+ of the population (the exception being the well muscled) both measures would give the same result.
http://prowellness.vmhost.psu.edu/prevention/understanding_risk/whtr5 -
If it makes you feel good to throw around terms like special snowflake to insult people, go right ahead. I have seen the threads. I have seen plenty of people for which BMI absolutely not an accurate measure of health. What I have never seen is BMI take into account body fat or blood pressure or cholesterol or even something as simple as waist size. Heck, a waist size chart would be better than BMI.
In my own experience BMI matched what was going on with my health. When my BMI was in the overweight category I was unhealthy with a high glucose number and not so great cholesterol numbers. As my BMI went down (ie I was losing weight), my blood panel numbers improved. Now I'm in the healthy BMI range and I also have excellent blood panels, great blood pressure etc. This may not be the case for everyone but it was for me at least.1 -
BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS. There are lots of unhealthy people at a "healthy BMI" and you don't have to look anything like the Rock to be at an overweight or even obese BMI, particularly men. If you want to know if you are healthy, look in the mirror, actually check your body fat, check your blood pressure, check your cholesterol, etc.
Yeah, it's so easy to be obese by BMI without being overfat, a 6 foot person would just have to be 220 pounds, putting them at least at 24 FFMI, and that's when you're at 20% bodyfat which is hardly the best bodyfat amount to have. That goes up to 26 if you go with an actually healthy bodyfat range. 25 FFMI is what's regarded barely still doable by people with great genetics. But yeah tell yourself so many people at healthy bodyfat amounts can be up to obese without that crazy amount of muscle.
I swear, the skewed perception perpetuated thanks to pro bodybuilders is gonna be the death of my sanity.4 -
stevencloser wrote: »BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS. There are lots of unhealthy people at a "healthy BMI" and you don't have to look anything like the Rock to be at an overweight or even obese BMI, particularly men. If you want to know if you are healthy, look in the mirror, actually check your body fat, check your blood pressure, check your cholesterol, etc.
Yeah, it's so easy to be obese by BMI without being overfat, a 6 foot person would just have to be 220 pounds, putting them at least at 24 FFMI, and that's when you're at 20% bodyfat which is hardly the best bodyfat amount to have. That goes up to 26 if you go with an actually healthy bodyfat range. 25 FFMI is what's regarded barely still doable by people with great genetics. But yeah tell yourself so many people at healthy bodyfat amounts can be up to obese without that crazy amount of muscle.
I swear, the skewed perception perpetuated thanks to pro bodybuilders is gonna be the death of my sanity.
First of all, you skipped the overweight range entirely. Secondly, use whatever calculations you want but it really isn't that hard to exceed the normal or even overweight BMI ranges and be healthy. Last time I lost weight, I was still considered obese according to BMI charts but had abs showing and a 32" waist. That was after only 3 months back in the gym. A couple of guys I work with have 6 packs and are both overweight according to BMI and one of them can't even bench 300. I would hardly call that a bodybuilder.0 -
Of course you do.3
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BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS.
That's not my understanding of what BMI is for at all.
It's a screening tool. Statistically, people beyond the normal BMI range have an increased risk of negative health effects. It's a simple and quick quide to help decide if further information is needed (all you need is height and weight - of course it's simplistic, but it's easy to use and overall a helpful indicator).
Of course it's prefectly possible to be healthy beyond the standard BMI range (and sometimes be unhealthy within it), bit it's not meant as an estimate of health by itself.
2 -
It's a good guideline for many and inaccurate for a few - that's how population measures work.
But far too many think they are one of the few!
^^^^ This.
Here's an illustration: The average number of children born per woman in the US in 2016 is 1.87. Yet I know of no one who actually has 1.87 children.
Source: CIA World Factbook
(https://www.cia.gov/library/publications/the-world-factbook/fields/2127.html)6 -
stevencloser wrote: »BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS. There are lots of unhealthy people at a "healthy BMI" and you don't have to look anything like the Rock to be at an overweight or even obese BMI, particularly men. If you want to know if you are healthy, look in the mirror, actually check your body fat, check your blood pressure, check your cholesterol, etc.
Yeah, it's so easy to be obese by BMI without being overfat, a 6 foot person would just have to be 220 pounds, putting them at least at 24 FFMI, and that's when you're at 20% bodyfat which is hardly the best bodyfat amount to have. That goes up to 26 if you go with an actually healthy bodyfat range. 25 FFMI is what's regarded barely still doable by people with great genetics. But yeah tell yourself so many people at healthy bodyfat amounts can be up to obese without that crazy amount of muscle.
I swear, the skewed perception perpetuated thanks to pro bodybuilders is gonna be the death of my sanity.
First of all, you skipped the overweight range entirely. Secondly, use whatever calculations you want but it really isn't that hard to exceed the normal or even overweight BMI ranges and be healthy. Last time I lost weight, I was still considered obese according to BMI charts but had abs showing and a 32" waist. That was after only 3 months back in the gym. A couple of guys I work with have 6 packs and are both overweight according to BMI and one of them can't even bench 300. I would hardly call that a bodybuilder.
I have abs, a 30" and a BMI slightly in the overweight range and I bench 1.6x my bodyweight, but so what? What does that have to do with most people? Those of us who know the BMI doesn't work for us aren't that fussed about it in general because we know it's a population measure. For individuals it's just one of many tools and there are better ones for individuals, but a BMI measurement can still be a good check.
Also, I seriously doubt you were in the obese range with a 10-15% BF unless you were running a decent stack. As Steve pointed out, you need to have a FFM that's extremely high and isn't something you get without drugs and years of serious training. Out of all of the bodybuilders, powerlifters, weight lifters (i.e. Olympic lifting) or wresters I've ever known (and I known tons), only a handful would ever have been BMI rated obese AND have an athletic BF% and they all had pro cards. I'm also not even going to touch the fact that these bodybuilders aren't really that healthy and their life expectancy is still reduced. It doesn't really matter how you get to obese BMI it doesn't seem to do much for longevity either way.10 -
BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS.
That's not my understanding of what BMI is for at all.
It's a screening tool. Statistically, people beyond the normal BMI range have an increased risk of negative health effects. It's a simple and quick quide to help decide if further information is needed (all you need is height and weight - of course it's simplistic, but it's easy to use and overall a helpful indicator).
Of course it's prefectly possible to be healthy beyond the standard BMI range (and sometimes be unhealthy within it), bit it's not meant as an estimate of health by itself.
There is even some evidence that being slightly above 25 but active and not on a yo-yo diet cycle can be better than being in normal range but having to fight to stay there all the time.
2 -
TrevorMcC85 wrote: »Hi everyone,
This has probably already been discussed but I would like to ask those in the know if BMI calculations are accurate?
I have read a few articles recently that speak negatively about them, even going as far to say that they are completely pointless.
I'm just starting out trying to get fit and healthy and am wondering is it a good measurement of where I am and where I would like to be?
Any help would be appreciated!
Trevor
BMI will be a rough guide only but should help you know where you should approximately be. Better measures for you would be BF% plus hip to waist ratio. It's not just how much fat you have but where you store it that's important and visceral fat should be minimized.0 -
They are a pretty good guideline in general.
0 -
Wheelhouse15 wrote: »stevencloser wrote: »BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS. There are lots of unhealthy people at a "healthy BMI" and you don't have to look anything like the Rock to be at an overweight or even obese BMI, particularly men. If you want to know if you are healthy, look in the mirror, actually check your body fat, check your blood pressure, check your cholesterol, etc.
Yeah, it's so easy to be obese by BMI without being overfat, a 6 foot person would just have to be 220 pounds, putting them at least at 24 FFMI, and that's when you're at 20% bodyfat which is hardly the best bodyfat amount to have. That goes up to 26 if you go with an actually healthy bodyfat range. 25 FFMI is what's regarded barely still doable by people with great genetics. But yeah tell yourself so many people at healthy bodyfat amounts can be up to obese without that crazy amount of muscle.
I swear, the skewed perception perpetuated thanks to pro bodybuilders is gonna be the death of my sanity.
First of all, you skipped the overweight range entirely. Secondly, use whatever calculations you want but it really isn't that hard to exceed the normal or even overweight BMI ranges and be healthy. Last time I lost weight, I was still considered obese according to BMI charts but had abs showing and a 32" waist. That was after only 3 months back in the gym. A couple of guys I work with have 6 packs and are both overweight according to BMI and one of them can't even bench 300. I would hardly call that a bodybuilder.
I have abs, a 30" and a BMI slightly in the overweight range and I bench 1.6x my bodyweight, but so what? What does that have to do with most people? Those of us who know the BMI doesn't work for us aren't that fussed about it in general because we know it's a population measure. For individuals it's just one of many tools and there are better ones for individuals, but a BMI measurement can still be a good check.
Also, I seriously doubt you were in the obese range with a 10-15% BF unless you were running a decent stack. As Steve pointed out, you need to have a FFM that's extremely high and isn't something you get without drugs and years of serious training. Out of all of the bodybuilders, powerlifters, weight lifters (i.e. Olympic lifting) or wresters I've ever known (and I known tons), only a handful would ever have been BMI rated obese AND have an athletic BF% and they all had pro cards. I'm also not even going to touch the fact that these bodybuilders aren't really that healthy and their life expectancy is still reduced. It doesn't really matter how you get to obese BMI it doesn't seem to do much for longevity either way.
The only way I can see someone who does not have unreasonably high lean mass having abs and being in the obese range, is someone with extreme levels of visceral fat and little subcutaneous, which needless to say is very unhealthy.2 -
stevencloser wrote: »Wheelhouse15 wrote: »stevencloser wrote: »BMI is all but worthless. It is supposed to be a reasonable estimate of a healthy level of body fat and in that regard it BS. There are lots of unhealthy people at a "healthy BMI" and you don't have to look anything like the Rock to be at an overweight or even obese BMI, particularly men. If you want to know if you are healthy, look in the mirror, actually check your body fat, check your blood pressure, check your cholesterol, etc.
Yeah, it's so easy to be obese by BMI without being overfat, a 6 foot person would just have to be 220 pounds, putting them at least at 24 FFMI, and that's when you're at 20% bodyfat which is hardly the best bodyfat amount to have. That goes up to 26 if you go with an actually healthy bodyfat range. 25 FFMI is what's regarded barely still doable by people with great genetics. But yeah tell yourself so many people at healthy bodyfat amounts can be up to obese without that crazy amount of muscle.
I swear, the skewed perception perpetuated thanks to pro bodybuilders is gonna be the death of my sanity.
First of all, you skipped the overweight range entirely. Secondly, use whatever calculations you want but it really isn't that hard to exceed the normal or even overweight BMI ranges and be healthy. Last time I lost weight, I was still considered obese according to BMI charts but had abs showing and a 32" waist. That was after only 3 months back in the gym. A couple of guys I work with have 6 packs and are both overweight according to BMI and one of them can't even bench 300. I would hardly call that a bodybuilder.
I have abs, a 30" and a BMI slightly in the overweight range and I bench 1.6x my bodyweight, but so what? What does that have to do with most people? Those of us who know the BMI doesn't work for us aren't that fussed about it in general because we know it's a population measure. For individuals it's just one of many tools and there are better ones for individuals, but a BMI measurement can still be a good check.
Also, I seriously doubt you were in the obese range with a 10-15% BF unless you were running a decent stack. As Steve pointed out, you need to have a FFM that's extremely high and isn't something you get without drugs and years of serious training. Out of all of the bodybuilders, powerlifters, weight lifters (i.e. Olympic lifting) or wresters I've ever known (and I known tons), only a handful would ever have been BMI rated obese AND have an athletic BF% and they all had pro cards. I'm also not even going to touch the fact that these bodybuilders aren't really that healthy and their life expectancy is still reduced. It doesn't really matter how you get to obese BMI it doesn't seem to do much for longevity either way.
The only way I can see someone who does not have unreasonably high lean mass having abs and being in the obese range, is someone with extreme levels of visceral fat and little subcutaneous, which needless to say is very unhealthy.
It's an unnatural fat distribution and the only people you see with protruding bellies and abs are the mass monsters in the IFBB who take large amounts of IGF-1 and thus have swollen internal organs. It's still not healthy to be like that and looks ridiculous.1 -
All I will say is that a few years ago, my doctor was all about BMI. Now he tends to be more concerned with waist to hip ratios along with BMI. For example, my husband is a fairly fit and strong guy who is at a good weight and works out regularly, but he still has metabolic syndrome. He could probably lose another 5-10 pounds, but he is within a fairly "healthy" BMI for his height. Our doctor is most concerned about his WHR. Whereas, my doctor would be thrilled if I just lowered my BMI by 7-10 points, even though I would still be in the "obese" range.
I think BMI is a good "guideline" but there are other indicators of health (like WHR, bloodwork, genetics, etc.) that should be taken into consideration.0
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