Weight Loss News and Current Events - BMI Flawed?




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Koolmum
03-14-2011, 08:16 PM
http://www.besthealthmag.ca/blog/post/news-is-the-body-mass-index-flawed

Maybe we put too much faith in our BMI. I would be interested to know my BAI.


MissKoo
03-14-2011, 10:20 PM
BMI is simply a height to weight ratio (with a gender difference thrown in?). How can that little number it comes up with tell you that you are obese if it doesn't know how much is you is fat, muscle or otherwise? I just doesn't make any logical sense.

Heather
03-14-2011, 10:40 PM
Yes, we put much too much faith in it.

BMI wasn't designed for individuals but has been co-opted for them because it's very easy to measure and does have correlates with health outcomes.

If you're interested, here's a decent article about the history and use of BMI: http://www.slate.com/id/2223095/

One excerpt:
"Belgian polymath Adolphe Quetelet devised the equation in 1832 in his quest to define the "normal man" in terms of everything from his average arm strength to the age at which he marries. This project had nothing to do with obesity-related diseases, nor even with obesity itself. Rather, Quetelet used the equation to describe the standard proportions of the human build—the ratio of weight to height in the average adult. Using data collected from several hundred countrymen, he found that weight varied not in direct proportion to height (such that, say, people 10 percent taller than average were 10 percent heavier, too) but in proportion to the square of height. (People 10 percent taller than average tended to be about 21 percent heavier.)"

And later:
"Keys had never intended for the BMI to be used in this way. His original paper warned against using the body mass index for individual diagnoses, since the equation ignores variables like a patient's gender or age, which affect how BMI relates to health. It's one thing to estimate the average percent body fat for large groups with diverse builds, Keys argued, but quite another to slap a number and label on someone without regard for these factors."


Vladadog
03-14-2011, 10:46 PM
I've never thought the BMI was 100% accurate when applied to any particular individual but it's a reasonable range of numbers to give you an idea of how your weight is effecting your health.

A couch potato who lives on junk food but is a "healthy" BMI is almost assuredly not healthier than an active obese person who eats well and exercises regularly.

When I was 285 I was cardiovascularly healthier than many morbidly obese people. I certainly didn't feel morbidly obese, but I was really overweight and I didn't need a BMI to tell me that.

Yesterday I was "obese" and today I am "overweight" - that's an arbitrary division on a chart but it does show a progression towards what is generally considered a healthier weight range. Ultimately it's just a number, as is the one on the scale. But it's a number that can help guide you.

ETA: i just checked my BAI (http://www.intmath.com/functions-and-graphs/bmi-bai-comparison.php) and, if my metric to non-metric conversions are correct my BAI is 33.4% which is in the healthy range. While this makes me happy it's still just a number.

Chrztina
03-15-2011, 09:32 PM
As a very short person (5'0'') I couldn't agree more. While, yes I've known that I am overweight, there was no way I was obese. I don't think I'm in denial, but even at my highest weight of 160, I still wore a size 10 without a big spare-tire flowing over the pants. Yet my BMI indicated that I was obese. Really, I'm not in denial, overweight yes, obese no.

My current BMI puts me at overweight, but my BAI puts me smack in the middle of healthy. My husband says I carry my weight well, which he meant to make me feel better, but I've known I've had work to do.

Heck, although my goal is 125 (barely a healthy BMI), I might just stop at 133 which is the weight I last felt really healthy and fit. According to BMI I could drop down to 95lbs and still be "healthy". In high school I was between 98-105 and I was tiny. Looking back I looked sick.

And I know that BMI shouldn't mean anything to me, but the truth is, it does. I feel I need something to look at in order to say - you did it. Or at least to not say "overweight".

Sorry for the rambling, but this new calculation just made my day!:D

shcirerf
03-16-2011, 12:43 AM
There are so many variables to the human body, I don't think it's fair to assign a number. I have one sister who is 5'9", (Kellee) her fat is squishy. My other sis who is about 5'7"(Lex) , even over weight, she is solid as a rock. Her fat does not jiggle. I'm 5'5", somewhere in between.

Kellee has a non physical job. Lex and I have very physical jobs. For me at my height, I'm good at around 145 to 150. I look good and feel good, and I can still do my job. The charts say I could get as low as 110. I'd be a stick that couldn't take out the trash at that weight.

What bugs me is that insurance companies and others have taken these math formulas and charts to heart, and if we can't meet what the chart says, we pay more. I bet you, I could take that little mathematical insurance guy and his charts, out back and whoop the you no what out of him.

Then there is the whole health issue. I have an uncle, who has never been overweight, eats right and gets plenty of exercise, and has horrid cholesterol. HE does all the right things. My Dh is while not overweight, has the most horrid habits in the world, loves fried food, bacon, gravy is a food group, smokes like a freight train and drinks like a fish, and his blood work, chest x-rays, etc. health nuts would kill for it. I'm not promoting what he does, just saying. Trying to get him to do better. I know it will catch up to him.

While the mathematical formulas can provide a guideline, they should not be the end all be all of what is healthy for each individual.

ElizabethG
03-16-2011, 01:55 PM
woot! I like that BAI. According to that I am a healthy weight. lol I am a healthy weight according to waist-hip ratio too.

K16
03-17-2011, 11:03 AM
I've never given much thought to BMI actually-- I never felt it was a very good indicator of my actual health. I was proven right when I was in a biology class and we all were 'weighed' on what I like to call a "bionic scale." It was simply a very fancy scale that measured numerous things. We also used one of those machines you hold with your arms and it sends an electric pulse through to determine body fat percentage.

I wasn't surprised to find that my friends who were very skinny, were mostly made up of fat. They don't exercise, they are weak, but they are skinny. I would much rather have my curves and have a health percent body fat :)

Magrat
03-18-2011, 06:10 AM
I checked out my BAI and I'm not happy. It says that with a 32" hip measurement my BAI is 23. That might be healthy but it sounds awfully high to me. I'd have to somehow get my hips down to a measly 30" in order to get my BAI down, and that's not going to happen unless I shave off some of my hipbones.

Grrr! I shouldn't have looked at the site. Now I have another reason to dislike my body.

Natalia
03-18-2011, 02:44 PM
I checked out my BAI and I'm not happy. It says that with a 32" hip measurement my BAI is 23. That might be healthy but it sounds awfully high to me. I'd have to somehow get my hips down to a measly 30" in order to get my BAI down, and that's not going to happen unless I shave off some of my hipbones.

Grrr! I shouldn't have looked at the site. Now I have another reason to dislike my body.

what??! the BAI number is not comparble to BMI numbers. Using the BAI graph, you are on the cusp of being underweight. I'm not understanding why you would want to get your number down further just becasue you don't like the number 23? :?:

rachael
03-18-2011, 03:23 PM
My BMI is 22.1. My BAI is BAI = 24.1% body fat. I'm closer to the middle/top of the range in the BMI, closer to the bottom on BAI.

Magrat
03-18-2011, 03:48 PM
what??! the BAI number is not comparble to BMI numbers. Using the BAI graph, you are on the cusp of being underweight. I'm not understanding why you would want to get your number down further just becasue you don't like the number 23? :?:


You're right I don't like the number if it means that my body is 23% fat.That seems very high and hard for me to believe given my waist and hip measurements (22 and 32 inches respectively). I'm not squishy so how can I be 23% fat?

Incidentally I never put much stock in BMI numbers. For any given height there is just too wide a spread of healthy weights.

Magrat
03-18-2011, 03:51 PM
Forget to add that I could never understand why a woman has to have any more fat than a man if she never intends to have children.

Makes no sense to me.

kaplods
03-18-2011, 04:11 PM
I checked out my BAI and I'm not happy. It says that with a 32" hip measurement my BAI is 23. That might be healthy but it sounds awfully high to me.


How can it "sound high" if you know nothing about BAI. It's like saying "Wow, 500 yen sure sounds like a lot of money..."

It's barely $6.00

You can't compare BAI to BMI, and you shouldn't choose a number based on what "sounds good" if you have no knowledge understanding behind it.

It's like going to a job interview as a waitress at IHOP, and when they ask you what salary you expect, you say, "How about $80,000 a year that sounds good."


People do this with weight too, and it's nuts, you need to know what the numbers can tell you, and what they are telling you, before you pick one because you like the number for no other reason than it "sounds good" It can only "sound good" if you know what it means. Otherwise, you're just picking a random number out of the air.

joyfulloser
03-18-2011, 07:54 PM
Forget to add that I could never understand why a woman has to have any more fat than a man if she never intends to have children.

Makes no sense to me.

Internal fat...we need more internal fat for child bearing!;)

Additionally, those figures (both BMI and BAI) are more than likely not accurate given your measurements. A good, fast and cheap way is to simply buy a $10 pair of calipers and manually measure your bodyfat.:)

Magrat
03-18-2011, 08:23 PM
Internal fat...we need more internal fat for child bearing!;)

Additionally, those figures (both BMI and BAI) are more than likely not accurate given your measurements. A good, fast and cheap way is to simply buy a $10 pair of calipers and manually measure your bodyfat.:)


But I never wanted kids so I (and I'm just speaking for myself here) never saw the need for me to have extra internal fat and since I'm now of an age where having kids is a moot point I certainly don't need extra fat now.

And I don't think that test is accurate. Just for fun I changed my weight status to 90 pounds and kept my other numbers true. Lo and behold my BAI numbered dropped to 17. This makes no sense since if I weighed 23 pounds less I should proportionately be fatter at the same size.

BMI is bad enough but at least it's a straight height to weight ratio. How can a formula know how much body fat a person carries?

To those who were happy with their numbers, sorry but I think the test is hogwash.

Theyda
04-13-2011, 07:24 AM
Never put much stock in BMI other than using it to choose a target weight to work towards. If I get to that weight and I don't think it's right I'll change it, BMI is just a rough guide for me.
I know that I've always had large breasts since I was about 12, before I put all my weight on so I've always been upset that the doctor doesn't take a persons physical build into account, they just put everyone through the same BMI machine.

ryeb
05-06-2011, 07:15 PM
I hate BMI!! I have been in decent shape before, and I was considered obese according to the chart. I am off to check my BAI now

AshleyLaurent
05-21-2011, 11:06 AM
Women naturally have more fat in their bodies.

However, I never took much stock in BMI. I took the results and I feel that the BAI is much more accurate....although I have a very small body frame.

BMI = 26.2 kg/m2-Overweight (25.0 – 29.9)

BAI = 24.9% body fat- Healthy (21 to 33%)

Kendrab1223
05-21-2011, 07:20 PM
Bmi- 24.5 (just barely made it into "normal" a couple pounds ago)
Bai- 27.5%

Why is the hip measurement the one to use? Just curious.

Both tell me I'm healthy/normal but I know I have a ways to go. I actually think I will need to lose more than what my original goal is but we'll see. Maybe 12 pounds now will make more of a difference now than it did 68 pounds ago? I have no clue.

NewGirl24
05-23-2011, 12:04 PM
oooh, I HATE the BAI method. According to it, I'm still obese.

I can't help that I have a small waist and a big arse. I'm not obese anymore.

I don't put too much stock into BMI either, though I like that system better because it tells me that I'm healthy, LOL. ;-)

April Snow
05-29-2011, 11:42 AM
I don't think BMI is completely accurate for individuals, but I don't know that BAI is much better. There was also a recent study showing that having a larger waist/being apple shaped is not necessarily linked to all the risks we've been told it is.

http://healthland.time.com/2011/03/11/apple-shapes-may-not-be-at-higher-risk-of-heart-disease-after-all/

runningfromfat
05-30-2011, 09:53 AM
I don't think BMI is completely accurate for individuals, but I don't know that BAI is much better. There was also a recent study showing that having a larger waist/being apple shaped is not necessarily linked to all the risks we've been told it is.

http://healthland.time.com/2011/03/11/apple-shapes-may-not-be-at-higher-risk-of-heart-disease-after-all/

Thanks for sharing that. Honestly, the whole issues seems to be way more complicated than simply taken one measurement (whether that be height, waist size, hip size etc) and one's weight.

I'm all over the place when it comes to these things. Here are my stats:

BMI- Obese (30.6)
BAI- Healthy (32.5%)
Waist Size- Healthy (34 inches)
Waist-to-Hip-Ratio- Healthy (0.79- it actually used to be smaller but I lost some inches around my hips)

So according to everything I'm at the very high range of healthy but according to my BMI I'm still obese. I know I still have a lot of weight to lose still so I'd guess in reality I'm probably somewhere in between. I think I'd trust these more if they took more measurements.

IsabellaOlivia
06-07-2011, 05:58 PM
I've never thought BMI was flawed, but then again I've never thought BMI was some universal formula for health. BMI is an easy tool for people to check very roughly their weight class and I do believe BMI is a better tool than weight alone. The fat around the midsection is the dangerous fat and therefore I believe that the waist-to-hip-ratio is a useful tool.
There needs to be a acknowledgement that no single tool is perfect, but they are not intended to be unflawed, they are merely meant as guidance.
If your BMI is in the obese class you probably need to lose weight, unless you're muscles are equal to the Terminator's in the late 80's. When it comes to the overweight and healthy weight categories then there is more leeway for body types to still be healthy and look good despite a high number.

RawrDinosaur
07-06-2011, 12:32 PM
For me, I feel like BMI has always been fairly accurate. The BAI seems straight up wrong for me personally. I can see it working for others, though.

BAI calls me "healthy" at 31%, but I feel anything BUT healthy at this weight. BMI calls me "overweight" at 29.6. And I am.
I look and feel best around a BMI of 21 or 22.

kaplods
07-06-2011, 02:40 PM
My husband has a friend who is in the "obese" class because he's so muscular. It's not fat, because you can see every muscle clearly. The guy looks pretty spectacular in a kilt (hubby and his friends are rpg gamers, and they sometimes get into character with costumes - though they make it clear that they're not NOT LARPers).

He's also is outrageously active and spends a lot of time in the gym. He was worried when he read his BMI. The doctor told him it was safe to lose a few pounds (still leaving him with an obese BMI), and the guy did, so now his muscle definition is even clearer, but it was pretty awesome before.

I'm not kidding myself though, it's unlikely that my BMI is (or possibly ever will be) overestimating my fatness.

RawrDinosaur
07-06-2011, 03:26 PM
Yeah, I feel like it tends to be more accurate for the average woman than for men, because of the muscle mass.

I'm actually a very muscular 196 lbs, but still have PLENTY of fat. lol
I think it takes quite a bit of density to throw off the BMI. For most of us here, it will be pretty close to accurate.

There's no harm in knowing both figures, though! Any info or calculation will help you, in some small way, to understand your body better.

PhatBeth
09-07-2011, 01:27 PM
I once did but I realized it a simple way of remaining stressed for the rest of my life.
Not many people can have a 100% result on the test of their BMI ( the ratio of height to weight).
There are very many people who are very healthy and a surprising result can be got on doing this test.
currently i concentrate on measures that reduce the amount of fat in my body.

thinner
09-07-2011, 10:52 PM
from what i've read, bmi was developed with the assumption that the shapes of the smaller size bodies would stay the same as the bigger size bodies, and we all know THAT doesn't happen! and, i've read that the old charts assume one inch heels. has a dr ever looked up your bmi and added one inch to your height?? not me. and not even mentioning the fact that people have muscle pounds not fat pounds...

dancerchickchic
09-07-2011, 11:13 PM
BMI is not the be all of deciding if you're overweight or not. It can be accurate for some people.

People in the military have been denied because of high BMI. THese people of course have a lot of muscle mass, and as we all know, muscle weighs more than fat. In these people's cases, they then take measurements. (at the neck, thigh etc.)

A more accurate predictor is using calipers (although this is only good if the person taking it is trained and this person is the only one who will be checking it for the rest of your life due to poor inter-rater reliability). An even more accurate predictor is using the bod pod. Look it up :)

(I am in school for this sort of thing...sat through a 3 hour lecture on this...)