Is BMI really BS?

1saturn
1saturn Posts: 95 Member
edited November 7 in Health and Weight Loss
So, everyone around me has been telling me not to look at numbers but instead how I feel. I don't like that I am on the heavier side of "healthy" and I'm close to being "overweight":brokenheart: . I've lost ten pounds and I want to lose another ten because it will put me at a much healthier looking BMI. Is this a good idea?
It's difficult because I don't dislike my body (that much) and I know some of my weight is muscle. Not a lot of it but I certainly have some tone in my legs. My mums telling me to keep loosing weight but my friends think it's unnecessary.
Do you think I should improve my BMI or is it all BS?
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Replies

  • darrensurrey
    darrensurrey Posts: 3,942 Member
    Agree with Iwishyouwell.
  • 1saturn
    1saturn Posts: 95 Member
    No, it's not BS. BMI is a generalization that will work for generally most people. It's become very common these days to attack BMI due to the outliers who have a higher than typical muscle mass, and thus for whom BMI is of little use. However the vast majority of people aren't rocking the amount of additional lean mass needed to skew the BMI radically.

    The heart of the matter, for many, is that they hate that BMI tells them they're still too fat. A lot of people have come to loathe the old height/weight chart ranges and BMI because they point to the fact that we've, on the whole, lost perspective of just how small most people need to be in order to not be overweight. Especially here in the US we've become very, very skewed about appropriate weight and BMI.

    As far as your own personal goals, are your health markers good? When looking in the mirror do you have excess fat that you're unhappy with? When you say you "dislike" your body, what exactly do you dislike? That there is still too much fat mass or are you talking about other parts that are unchangeable (naturally speaking)?

    I can agree with this to some extent. The only problem is body shape. It doesn't take into account anything other than numbers. I don't think that can be too accurate as people are so diverse. Obviously, in some cases it does work fine. When it comes to my doctor, I was told I am "healthy" and "fine" in terms of weight.
    I have a love hate relationship with my body. Sometimes I quite like it others I don't. I don't think I am fat or big. My dislike for my body comes from problem areas (inner thighs, legs etc). So I can never be sure how to feel about myself or how much I need to commit to weight loss.
    BMI is the only thing really that's making me lose weight.
  • SezxyStef
    SezxyStef Posts: 15,267 Member
    For individuals yes I believe it is an antiquated calculation that has to much importance put on it.

    For general public yes it's fine.

    The history of BMI comes from the 1800's.

    "...it is meant to be used as a simple means of classifying sedentary (physically inactive) individuals, or rather, populations, with an average body composition"

    http://www.webmd.com/diet/features/how-accurate-body-mass-index-bmi

    For me atm I have a BMI of 24...puts me on the high side of "healthy"...I personally feel that my weight atm is great...I wear a size 5/6 and the 5-6 pounds I lost to get below overweight didn't change my clothing size or my fitness level...

    So 2 months ago I was considered "overweight"...sorry I have to laugh...at 160lbs..in a size 5/6...not overweight...
  • 1saturn
    1saturn Posts: 95 Member
    I think the only people on the planet to whom you should listen regarding your weight loss goals are your doctor, and the person in your mirror, but that's just me.

    Well, my doctor said I'm healthy but it's discouraging to see BMI doesn't exactly think so.
  • Wonderob
    Wonderob Posts: 1,372 Member
    BMI doesn't distinguish between fat and muscle so it's certainly massively flawed

    Pick any muscly athlete and BMI will say they are overweight

    eg. Running back Adrian Peterson

    espn_2009bww_21.jpg

    Not overweight surely? Well the BMI checker isn't ambiguous in any way: "Adrian Peterson BMI is overweight"

    http://www.celebheightandweight.com/adrian-peterson-bmi-848.html

    I know that doesn't really help you but quite interesting anyway???
  • Siannah
    Siannah Posts: 456 Member
    No, it's not BS. BMI is a generalization that will work for generally most people. It's become very common these days to attack BMI due to the outliers who have a higher than typical muscle mass, and thus for whom BMI is of little use. However the vast majority of people aren't rocking the amount of additional lean mass needed to skew the BMI radically.


    This! I'm sure the gorgeous athlete in the previous post knows he's not overweight. But for the normal plebs like me BMI is something to keep an eye on.
  • neandermagnon
    neandermagnon Posts: 7,436 Member
    No, it's not BS. BMI is a generalization that will work for generally most people. It's become very common these days to attack BMI due to the outliers who have a higher than typical muscle mass, and thus for whom BMI is of little use. However the vast majority of people aren't rocking the amount of additional lean mass needed to skew the BMI radically.

    The heart of the matter, for many, is that they hate that BMI tells them they're still too fat. A lot of people have come to loathe the old height/weight chart ranges and BMI because they point to the fact that we've, on the whole, lost perspective of just how small most people need to be in order to not be overweight. Especially here in the US we've become very, very skewed about appropriate weight and BMI.

    As far as your own personal goals, are your health markers good? When looking in the mirror do you have excess fat that you're unhappy with? When you say you "dislike" your body, what exactly do you dislike? That there is still too much fat mass or are you talking about other parts that are unchangeable (naturally speaking)?

    speaking as an outlier... I was told as an adolescent that I had to "be careful" because I was "almost overweight" by a well meaning adult, and told by another adult who should have known better, that I need to lose 10kg (22lb) based on BMI alone... I had visible upper abs at the time, my body fat percentage would have been around 18-20%.... very dangerous advice, both in terms of my physical and mental health.

    the problem is, while you're correct when BMI is applied to the average person, people who are outliers may not know that they are outliers, and most really don't know the difference between someone who has a high body fat percentage and someone who has a healthy body fat percentage and a high lean body mass for their height. It took my studying human sciences at degree level to understand that I'm an outlier and should take BMI with a pinch of salt, unfortunately I'd already suffered several years of disordered eating due to thinking I was too fat when I wasn't at all. And outliers are more common than people think, because most people don't really understand much about statistics and human variation.

    Really posts like the OP's rings alarm bells for me, because if she is like me, then she should absolutely NOT feel that she should have a lower BMI just to be more average... to attempt that could result in her harming her health rather than helping it. Yes outliers are rarer and statistically speaking it's *more likely* that she's not an outlier... but we do exist and are not all that rare, and someone on an internet forum can't tell the difference.

    OP: get your body fat percentage measured in a reliable way. If that's in the healthy range, then forget this idea of losing extra weight just to be in a certain place on a BMI chart. Body fat percentage is a direct measure of how much fat there is in your body. If it's in the healthy range, you don't have too much fat and your health is not at risk, regardless of what your BMI is (BMI is just a very crude way to estimate whether someone has too much body fat - body fat percentage actually measures how much fat you have). If your BF% is above 28% then losing more fat until it's in the healthy range (18-28%) is a good idea. Losing a little fat to be a lower number within the healthy range is fine too, but it's a purely cosmetic adjustment which won't affect your health either way. Some people like how their bodies look better at a particular percentage rather than another... I think I look best at around 23% body fat. But in terms of health, if it's in the healthy range then you have the right amount of body fat for good health.
  • 1saturn
    1saturn Posts: 95 Member
    For individuals yes I believe it is an antiquated calculation that has to much importance put on it.

    For general public yes it's fine.

    The history of BMI comes from the 1800's.

    "...it is meant to be used as a simple means of classifying sedentary (physically inactive) individuals, or rather, populations, with an average body composition"

    http://www.webmd.com/diet/features/how-accurate-body-mass-index-bmi

    For me atm I have a BMI of 24...puts me on the high side of "healthy"...I personally feel that my weight atm is great...I wear a size 5/6 and the 5-6 pounds I lost to get below overweight didn't change my clothing size or my fitness level...

    So 2 months ago I was considered "overweight"...sorry I have to laugh...at 160lbs..in a size 5/6...not overweight...


    Yes. I heard that BMI was created by a mathematician who had no intention of it being used as a measure of health. I think my BMI is about 24 too. But I don't feel (nearly) overweight or anything. I actually also used to waist to hip indicator and it said I was "excellent". Some people argue where fat is distributed is the real indicator of health so it's so confusing! I also used the waist to height ratio and it said I was too thin! I mean, really? What are we supposed to listen to I don't even know...
  • _Zardoz_
    _Zardoz_ Posts: 3,987 Member
    BMI is a guide and not meant to be used in isolation. It's a simple way with limited equipment to assess people. The problem is even some doctors and health professionals do that and forget to use some common sense. BMI is based on population averages and the majority of people will fit into it. It obviously was not designed to assess athletes.

    Those who immediately jump on the BMI is rubbish because look at me I lift and I'm technically over weight are missing the point. Yes some people wont fit in but in general the majority will and with the use of some common sense you can take it as a guide. I also have noticed a number of people slating BMI who are really just in denial about their own weight

    So look at your BMI look in the mirror and be honest with yourself. It's all data and with any information in needs to be taken in context.
  • Iwishyouwell
    Iwishyouwell Posts: 1,888 Member

    So 2 months ago I was considered "overweight"...sorry I have to laugh...at 160lbs..in a size 5/6...not overweight...

    Clothing sizes is about the worse marker available when determining appropriate weight.

    Almost all clothes in the US are vanity sized, and women's clothing has absolutely no regulations or standards. A 5/6 today can be so vanity sized that it was a 10-12, or higher, in decades past. Even men's clothes no longer follow the actual inches printed on the waist sizes. Hell I have two pairs of jeans from the 90s in a size 36 that are smaller than some size 33s today.

    The mirror and your health markers are the best standard, clothing size the absolute worse.
    BMI doesn't distinguish between fat and muscle so it's certainly massively flawed

    Pick any muscly athlete and BMI will say they are overweight

    eg. Running back Adrian Peterson

    And yet how much of the general population has a body built like a professional running back?
  • bennettinfinity
    bennettinfinity Posts: 865 Member
    The BMI is a poor metric to apply to individuals (esp. individuals that are not 19th century Belgians :wink: ) because it ignores the square/cubed law in order to keep the math simple.

    Here's a link to an interesting read about the science behind the flaws: http://people.maths.ox.ac.uk/trefethen/bmi.html

    And a link to an alternate calculation that accounts for the fact that people are three dimensional and provides a comparison of the two measures: http://people.maths.ox.ac.uk/trefethen/bmi_calc.html

    Bottom line: BMI is a poor analog to measuring BF% (and thus level of 'health') - in consistently underestimates BF% for shorter people and overestimates BF% for taller people. If you're taller than average, you should think twice before taking drastic measures to hit an arbitrary BMI number.

    My $0.02
  • rfw24
    rfw24 Posts: 443 Member
    BMI is not always BS but it can be. Like one of the poster says, "look at Adrian Peterson". Having a lot of muscle will skew the BMI #s.

    But with you saying your doctor says you are in the healthy range, that is a good start. You know you want and can get lower, so go for it! Stay positive!
  • Dewymorning
    Dewymorning Posts: 762 Member
    For studies of the general population BMI is a useful tool as all you need are everyone's weight and height, easy measures to obtain.

    For an individual, it could potentially be very inaccurate.
  • aneary1980
    aneary1980 Posts: 461 Member
    It depends on your build and general shape.

    For me and my Mum the weight range is about right in fact being smack in the middle of the healthy range is the perfect weight for both of us.

    My dad however has really short legs 29inches but is 6'2" so has a long body and is very broad and would be way too thin if he was in the healthy range he doesn't have lots of lean muscle but just has an odd shape.

    Basically if you feel healthy at your current weight then great if you have 'problem areas' you may be better off tonning them with exercises so they look better rather than trying to loss weight which could come off anywhere. :) Or finding clothes that suit your shape.

    From your picture I think you look fine.
  • bennettinfinity
    bennettinfinity Posts: 865 Member

    So 2 months ago I was considered "overweight"...sorry I have to laugh...at 160lbs..in a size 5/6...not overweight...

    Clothing sizes is about the worse marker available when determining appropriate weight.

    Almost all clothes in the US are vanity sized, and women's clothing has absolutely no regulations or standards. A 5/6 today can be so vanity sized that it was a 10-12, or higher, in decades past. Even men's clothes no longer follow the actual inches printed on the waist sizes. Hell I have two pairs of jeans from the 90s in a size 36 that are smaller than some size 33s today.

    The mirror and your health markers are the best standard, clothing size the absolute worse.
    BMI doesn't distinguish between fat and muscle so it's certainly massively flawed

    Pick any muscly athlete and BMI will say they are overweight

    eg. Running back Adrian Peterson

    And yet how much of the general population has a body built like a professional running back?

    I'm 210# @ 6'2" with a BMI of 27 (Overweight): my current BF is 20%, so I'll buy the BMI determination. However, I'm currently progressing towards my goal to recomp to 210# @ 15% BF, which would put me squarely in the 'athletic' range. My BMI will still be 27 and will not reflect any of the positive change I will have made. So how is this a good metric?
  • 1saturn
    1saturn Posts: 95 Member

    So 2 months ago I was considered "overweight"...sorry I have to laugh...at 160lbs..in a size 5/6...not overweight...

    Clothing sizes is about the worse marker available when determining appropriate weight.

    Almost all clothes in the US are vanity sized, and women's clothing has absolutely no regulations or standards. A 5/6 today can be so vanity sized that it was a 10-12, or higher, in decades past. Even men's clothes no longer follow the actual inches printed on the waist sizes. Hell I have two pairs of jeans from the 90s in a size 36 that are smaller than some size 33s today.

    The mirror and your health markers are the best standard, clothing size the absolute worse.
    BMI doesn't distinguish between fat and muscle so it's certainly massively flawed

    Pick any muscly athlete and BMI will say they are overweight

    eg. Running back Adrian Peterson

    And yet how much of the general population has a body built like a professional running back?

    Okay, but how am I supposed to know what to follow? My waist to hip ratio is excellent and my waist to height ratio implies I am too thin. So with all the "science" conflicting itself what now?
  • vidoardes
    vidoardes Posts: 70 Member
    Sorry I have to totally disagree with Iwishyouwell, BMI as a number for an individual is totally, completely and utterly useless.

    It is an extremely antiquated formula (originally known as the Quetelet Index) and simply doesn't give an accurate representation of health unless you happen to be a sedentary person of average height. It's main flaw is based on the way it is calculated, which is mass / height^2. The common argument is that if you have a good lean body mass, and muscle is more dense than fat, your BMI will be high when you perfectly healthy, but the main problem is that is starts from a datum of a standard height, and then scales up or down depending on if you are shorter or taller, but tall people aren't just scaled up short people, the formula breaks down as soon as you start to move away from the datum and the further you move away the more inaccurate it gets. Many, many studies have show it is useless for indicating cardiovascular disease, heart attack, stroke, and it's not even a great indicator of diabetes.

    In short, ignore BMI. If you want a simple measure of health, the waist to height ratio has proven much more effective, but really you need to measure body fat percentage, either with a pair of callipers or with a set of scales that can detect resistance. The scales tend not to be too accurate in there reading of BF%, but anything is better than BMI.

    Also checkout the Body Scale Index, which has been developed to overcome the shortcomings of BMI.

    http://absi-calc.appspot.com/
  • Wonderob
    Wonderob Posts: 1,372 Member
    No, it's not BS. BMI is a generalization that will work for generally most people. It's become very common these days to attack BMI due to the outliers who have a higher than typical muscle mass, and thus for whom BMI is of little use. However the vast majority of people aren't rocking the amount of additional lean mass needed to skew the BMI radically.


    This! I'm sure the gorgeous athlete in the previous post knows he's not overweight. But for the normal plebs like me BMI is something to keep an eye on.

    Sure the athlete knows he isn't overweight and of course that is the usual extreme example to prove the point that BMI is flawed in that respect

    Yes BMI is a 'pretty good' indication of whether normal people are overweight, but when like the OP you're not even talking about the line between 'normal' and 'overweight' - when you're talking about the 'heavier side of healthy' it can be misleading

    Unfortunately I look nothing like the super athlete in the photo, however after lifting weights regularly, my BMI was just over 25, yet I had a low body fat and my doctors said I wasn't overweight. I'm certainly in the 'normal' category and it seems I have a lot less muscle mass than most of the lifting guys on MFP
  • Iwishyouwell
    Iwishyouwell Posts: 1,888 Member

    So 2 months ago I was considered "overweight"...sorry I have to laugh...at 160lbs..in a size 5/6...not overweight...

    Clothing sizes is about the worse marker available when determining appropriate weight.

    Almost all clothes in the US are vanity sized, and women's clothing has absolutely no regulations or standards. A 5/6 today can be so vanity sized that it was a 10-12, or higher, in decades past. Even men's clothes no longer follow the actual inches printed on the waist sizes. Hell I have two pairs of jeans from the 90s in a size 36 that are smaller than some size 33s today.

    The mirror and your health markers are the best standard, clothing size the absolute worse.
    BMI doesn't distinguish between fat and muscle so it's certainly massively flawed

    Pick any muscly athlete and BMI will say they are overweight

    eg. Running back Adrian Peterson

    And yet how much of the general population has a body built like a professional running back?

    I'm 210# @ 6'2" with a BMI of 27 (Overweight): my current BF is 20%, so I'll buy the BMI determination. However, I'm currently progressing towards my goal to recomp to 210# @ 15% BF, which would put me squarely in the 'athletic' range. My BMI will still be 27 and will not reflect any of the positive change I will have made. So how is this a good metric?

    It's a good metric for the general population.

    The general population is not "6'2" looking to "recomp" their body to 210lbs at 15% bodyfat".

    All general metrics have outliers. Every single one. Slating a general system to compensate for a minority outlier is senseless.

    Obviously if someone has a higher than usual lean mass, yet are lean and rocking a low body fat level, they're not a candidate for the BMI range. But how much of any given population fits into this criteria?

    And why is it that most countries in the world have populations that fit well within the BMI range, yet it's almost always Americans who are railing against how wrong the BMI is?
  • vibra_studio
    vibra_studio Posts: 1
    I'm a fitness professional of 15yrs and we don't go by BMi it's just indication and a very small one. Measure your waist with tape measure, find decent wellness coach that can weigh you usingn scales I do that show body fat, muscle and water.
  • Iwishyouwell
    Iwishyouwell Posts: 1,888 Member
    The BMI is a poor metric to apply to individuals (esp. individuals that are not 19th century Belgians :wink: ) because it ignores the square/cubed law in order to keep the math simple.

    Here's a link to an interesting read about the science behind the flaws: http://people.maths.ox.ac.uk/trefethen/bmi.html

    And a link to an alternate calculation that accounts for the fact that people are three dimensional and provides a comparison of the two measures: http://people.maths.ox.ac.uk/trefethen/bmi_calc.html

    Bottom line: BMI is a poor analog to measuring BF% (and thus level of 'health') - in consistently underestimates BF% for shorter people and overestimates BF% for taller people. If you're taller than average, you should think twice before taking drastic measures to hit an arbitrary BMI number.

    My $0.02

    Yet, once again, BMI isn't a static number. It has built in a very wide range. Most people are going to be able to find a healthy, fit weight within a BMI ranging as radically as 30 or so pounds.

    Most. Not all. But most.
  • Wonderob
    Wonderob Posts: 1,372 Member

    So 2 months ago I was considered "overweight"...sorry I have to laugh...at 160lbs..in a size 5/6...not overweight...

    Clothing sizes is about the worse marker available when determining appropriate weight.

    Almost all clothes in the US are vanity sized, and women's clothing has absolutely no regulations or standards. A 5/6 today can be so vanity sized that it was a 10-12, or higher, in decades past. Even men's clothes no longer follow the actual inches printed on the waist sizes. Hell I have two pairs of jeans from the 90s in a size 36 that are smaller than some size 33s today.

    The mirror and your health markers are the best standard, clothing size the absolute worse.
    BMI doesn't distinguish between fat and muscle so it's certainly massively flawed

    Pick any muscly athlete and BMI will say they are overweight

    eg. Running back Adrian Peterson

    And yet how much of the general population has a body built like a professional running back?

    Not many - but plenty have enough muscle to put themselves in the BMI 'overweight' category, whilst they are not overweight

    Use BMI only if you're 'normal'??? What do we use to determine if we are 'normal'?
  • SezxyStef
    SezxyStef Posts: 15,267 Member

    So 2 months ago I was considered "overweight"...sorry I have to laugh...at 160lbs..in a size 5/6...not overweight...

    Clothing sizes is about the worse marker available when determining appropriate weight.

    Almost all clothes in the US are vanity sized, and women's clothing has absolutely no regulations or standards. A 5/6 today can be so vanity sized that it was a 10-12, or higher, in decades past. Even men's clothes no longer follow the actual inches printed on the waist sizes. Hell I have two pairs of jeans from the 90s in a size 36 that are smaller than some size 33s today.

    The mirror and your health markers are the best standard, clothing size the absolute worse.
    BMI doesn't distinguish between fat and muscle so it's certainly massively flawed

    Pick any muscly athlete and BMI will say they are overweight

    eg. Running back Adrian Peterson

    And yet how much of the general population has a body built like a professional running back?

    I am not from the states...and I can tell from the mirror that I was not overweight...and to your point of vanity sizes...I am 41...put my prom dress on while I weighed 165lbs...yes a 20 year old dress...so no vanity sizing there...I was 135lbs when I graduated...it fit like a glove....it was a size 8....I was not overweight at 165 either even tho BMI put me there...

    Here is some more history on BMI...it was developed to help the government ie monarchy, distribute goods during lean times in Europe...

    Even health care professionals are saying BMI is not the gold standard as it once was thought to be...

    As to the professional athletes being in the overweight or even obese category..no they aren't typically but let's be realistic.

    Lifters outside of professional athletes and people with larger frames are going to not be able to rely on BMI...me being one..

    I have a large frame, I lift heavy and at 165 I was in a 20 year old size 8....I was not obese. I am a normal everyday woman, just like lots of woman here...BMI for individuals is rubbish period....it is good for "general population" in groups.

    If you somehow manage to fit in BMI ranges as an individual that means you are "like the average" but that doesn't mean we all are.
  • arlenejoneswilson
    arlenejoneswilson Posts: 49 Member
    congratulations on making your weight goal!

    Q: are you stil going to use MFP?
  • thelowcarbrecipes
    thelowcarbrecipes Posts: 89 Member
    Im not 100% but I think I read that BMI was made / is used to generalise population weight and not meant to be for just looking at individuals. I dont have any sources for that.
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