My 1,000 word essay on why BMI isn't useful for a sample size of 1
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That picture looks just like you yanked it straight from an introductory statistics textbook, with the title "strong positive correlation "15
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amusedmonkey wrote: »KrazyKrissyy wrote: »I was overweight by 25 pounds in 2016. Am a size 2 and was back then as well. I had a huge blockage in my intestines that had to be removed. Lost the weight immediately. BMI is not helpful.
Edit: Woo= denial. Lol. It's ok if you don't believe me. My medical records are stashed away anyways
I did not woo, but I can speculate why someone would. It's not that they don't believe you, it's that this is a medical case so it's automatically not the norm, just like protein recommendations being helpful even when there are people who have medical conditions where they need to severely limit protein intake.
Out of curiosity, you're a size 2 and a 25 BMI right now? In that case, you're an extreme outlier even without the medical issues you had.
My BMI was 25 back in 2016 (I mentioned that already). Its not anymore. The blockage is gone.3 -
OK, so it looks like we have established that BMI is not useful because I'm assuming it's not predictably accurate for:
- Women with 25 lb intestinal blockages.
- Two individuals who according to OP's graphic seem to have 0% bodyfat, which is likely physically impossible.
- Bob and Roger.
BMI is a guideline that works quite well when considered as part of a group of measurements, like weight, BF%, waist measurement, activity level, fitness level, BP, resting heart rate, etc. Most if not all of those measurements are generally useful but can be misleading for any one individual if viewed on it's own. A minimally intelligent person with a genuine desire to quantify their individual level of health is more than capable of considering some or even all of these measurements with the help of their doctor to reach a meaningful conclusion. There is no one measurement, nor is it reasonable to expect there to be, that can fully express the entirety of an individual's health.
While the OP doesn't mention it, I agree that the insurance industry's reliance on BMI is wrong headed.
If you are grouchy because you think your weight is fine but you still fall in the overweight or obese BMI, do the work of getting those other measurements taken. I'd bet for the vast majority of the people in that situation, they'll find that several other markers will tell them they need to lose weight. If not, congratulations, you're an outlier. Maybe get that on a tee shirt or something.
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KrazyKrissyy wrote: »amusedmonkey wrote: »KrazyKrissyy wrote: »I was overweight by 25 pounds in 2016. Am a size 2 and was back then as well. I had a huge blockage in my intestines that had to be removed. Lost the weight immediately. BMI is not helpful.
Edit: Woo= denial. Lol. It's ok if you don't believe me. My medical records are stashed away anyways
I did not woo, but I can speculate why someone would. It's not that they don't believe you, it's that this is a medical case so it's automatically not the norm, just like protein recommendations being helpful even when there are people who have medical conditions where they need to severely limit protein intake.
Out of curiosity, you're a size 2 and a 25 BMI right now? In that case, you're an extreme outlier even without the medical issues you had.
My BMI was 25 back in 2016 (I mentioned that already). Its not anymore. The blockage is gone.
I must have misunderstood then. I thought you were 25 pounds overweight, which would mean way higher than 25 BMI. Even with your condition, you were only a fraction of a pound overweight. Goes to show how wide of a range normal BMI has to accommodate most people.5 -
KrazyKrissyy wrote: »I was overweight by 25 pounds in 2016. Am a size 2 and was back then as well. I had a huge blockage in my intestines that had to be removed. Lost the weight immediately. BMI is not helpful.
Edit: Woo= denial. Lol. It's ok if you don't believe me. My medical records are stashed away anyways
You would classify as an outlier with that type of medical condition.
NEXT.6 -
It is practical to reduce people to numbers when you are dealing with large populations. It is also practical to generate those numbers using simple formulas based on easily obtained and available data. That is what BMI is for...large scale population evaluations. It is useful for that. It is not practical to run around body-calipering or DEXA scanning millions of people.10
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I would initially evaluate the data and methodology used to obtain it. The data needs scrutinized before making a pretty picture. It means nothing without knowing the DOE controls.
People are impressed with charts and graphs and lots of data points and...I'm not sure why, other than they look good at a glance. They are only as good (or bad?) as the data they are derived from. I'll step off my technical soapbox now.
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The post is 2 years old. Nothing wrong with resurrecting old threads, but just letting you know.
I like BMI as a concept. A lot. The clarity and simplicity of it. If you're Class III obese, that means what it means. If you're Normal, that means what it means, too.
When I go to a doctor appt, the top page of my care summary, upper right hand corner in big, bold font: BMI and BP. Everything else like my aches and pains are footnotes to that header info for my physician. BMI is what docs use to get their snapshot of your health risks. It's what insurance companies use to gauge how long you're going to live, based on their actuarial tables.
I love how BMI syncs with clothing sizes, at least in my case. Class III obese, where I started my diet = men's 3x. Class II obese = 2x. Class I obese = XL. Presumably, when I get there, Overweight = L. I can tell from BMI what size to buy LOL
Never understood the antagonism to BMI here on MFP. Sure, there are outliers with unusual body compositions that don't fit neatly on a BMI chart - phenomenally conditioned bodybuilders who are classified as "obese" when they are just ripped, for example. But for us average Joes and Janes, BMI provides a useful, simple, clear snapshot of things. And no one ever said BMI tells you how healthy you are. The only thing that's ever been claimed is that a higher BMI has a statistically demonstrated correlation to various ailments, which we'd like to avoid.9 -
Leaving aside OP's chart - because I am not a graph person and I dont really understand what it is saying and it has obvious inaccuracies if it includes subjects with 0% body fat
I dont get the antagonism either.
BMI is a useful guide for the vast majority of people - and for those who are genuine outliers, this is obvious both to themselves and their doctors.
Does anyone really not know, or think a doctor would not see, that they are an elite body builder or an amputee or a person with dwarfism or 9 months pregnant or have a huge instestinal tumour or any other reason why standard BMI calculations would not apply to them??
So, sure, in OP's words, BMI is not a useful number for those n = 1 people.
No kidding.
My own n=1 - as a not very muscular middle aged woman with a BMI of 28 - both my doctor and myself and any casual observer could tell it wasnt an abnormal amount of muscle or a medical condition - I was plain old over weight.
am healthier now and less likely to develop weight related medical conditions, with a BMI of 23.10 -
paperpudding wrote: »Leaving aside OP's chart - because I am not a graph person and I dont really understand what it is saying and it has obvious inaccuracies if it includes subjects with 0% body fat
I dont get the antagonism either.
BMI is a useful guide for the vast majority of people - and for those who are genuine outliers, this is obvious both to themselves and their doctors.
Does anyone really not know, or think a doctor would not see, that they are an elite body builder or an amputee or a person with dwarfism or 9 months pregnant or have a huge instestinal tumour or any other reason why standard BMI calculations would not apply to them??
So, sure, in OP's words, BMI is not a useful number for those n = 1 people.
No kidding.
My own n=1 - as a not very muscular middle aged woman with a BMI of 28 - both my doctor and myself and any casual observer could tell it wasnt an abnormal amount of muscle or a medical condition - I was plain old over weight.
am healthier now and less likely to develop weight related medical conditions, with a BMI of 23.
Agreed. BMI is a model that measures people, not math that can be proven in absolute terms. "Healthy" or "unhealthy" is not a binary, it's a model that gives guidelines that are relevant to most people. Since "healthy" isn't binary, there's not really a definite limit between "normal weight" and "overweight", those are constructs created as guidelines as well.
My own n=1: My current BMI is 33 and there is no question that I am overweight/obese. However, all body composition measurements I've taken (multiple), health professionals' estimations and my past experience indicate that my "ideal" or "healthy" weight would likely be at BMI 25-26, which would still make me overweight according to BMI charts. While in that case BMI wouldn't be exactly "correct" in that sense, there's no question in my mind that it's a good indicator of which direction I should take.2 -
Hipari - yes I agree. The BMI chart is a spectrum not an absolute Yes or No cut off.
we sometimes see threads where people are saying I am fit, I go to the gym, I have lost weight but I cant get my BMI below 25.1 - as if somehow 24.9 and 25.1 were some massive difference and that 0.1% is going to change everything.
But, barring obvious outliers, examples as in my post above yours, the vast majority of people can be sure 33 is not a healthy BMI for them.
However, as I have stated on these threads before, there are sporty muscular young men who are quite healthy slightly above the official cut off point - ie with a BMI of around 26 -28
Not elite body builders - just fit sporty young men.
Again I was a not so fit 50 year old woman, not a sporty muscular young man - and I didnt need a doctor or a chart to tell me that the exceptions of 28 being upper end of healthy did not apply to me.
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@paperpudding exactly. I’m fairly muscular (under the fat), with a large frame, wide pelvis (hip bones) and big boobs, so putting a healthy fat percentage on top of all that easily leads to a BMI that’s slightly over 25. From BMI 33 it’s pretty clear that there’s only one direction, but the distance to ”healthy” can’t be defined on exact terms.
BMI is a great indicator, not an absolute truth.2 -
I was one of those who was against the BMI for years until I finally got a grasp of what the BMI was saying and that it was a statistical average and was really communicating risk of health problems. I think it comes in to a common misunderstanding and miscommunication of the point behind the number for a given person - the common perception is that if you are above a 25, then you have to be "unhealthy" no matter how active or fit you really are. And medical doctors for a long time pushed that number; nowadays they seem to be getting away from using it as a hard and fast rule, or at least, its seems that way in my experience. I'm hearing a lot more advice on losing 5% of your current weight and not so much on the BMI number. Not sure about the insurance companies, though.
For me personally, I seriously doubt I'll ever make it to that magical 25 BMI; I"m getting older and I don't think I have the patience or the fortitude it takes to be super tight on your logging to lose those last 10-15 lbs. I can live with being in the "overweight" category; its still worlds healthier and a much better risk profile than what I had when I was stage III obese.0 -
bmeadows yes of course it is about relative risk.
Being whatever your BMI is when you are 10 - 15 lb overweight is obviously less risk than being morbidly obese - and that is often presented in the incremental degrees of even losing 5% of your bodyweight decreases your risk.
of course if one is very over weight one would be advised to continue losing, not stop at 5%.
But every 5% is better than nothing.6 -
paperpudding wrote: »Leaving aside OP's chart - because I am not a graph person and I dont really understand what it is saying and it has obvious inaccuracies if it includes subjects with 0% body fat
I dont get the antagonism either.
BMI is a useful guide for the vast majority of people - and for those who are genuine outliers, this is obvious both to themselves and their doctors.
Does anyone really not know, or think a doctor would not see, that they are an elite body builder or an amputee or a person with dwarfism or 9 months pregnant or have a huge instestinal tumour or any other reason why standard BMI calculations would not apply to them??
So, sure, in OP's words, BMI is not a useful number for those n = 1 people.
No kidding.
My own n=1 - as a not very muscular middle aged woman with a BMI of 28 - both my doctor and myself and any casual observer could tell it wasnt an abnormal amount of muscle or a medical condition - I was plain old over weight.
am healthier now and less likely to develop weight related medical conditions, with a BMI of 23.
Just a guess, but I think this (the OP) sets peoples' BS detectors off.1 -
I think waist measurement is a better indicator, at least for men. If you don't trust the BMI chart, measure your waist and find out if it's ok relative to your height.1
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Why would you not trust the BMI chart??
Or more correctly, using the BMI chart in context ??2 -
I think waist measurement is a better indicator, at least for men. If you don't trust the BMI chart, measure your waist and find out if it's ok relative to your height.
The waist measurement is another good screening tool. For the vast majority of people it's results as to putting people in categories will be the same as BMI measurement.4
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