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Is every single body in the world intended to be within the so-called healthy BMI range?

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Replies

  • stanmann571
    stanmann571 Posts: 5,736 Member
    edited November 2017
    jdlobb wrote: »
    jdlobb wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    SezxyStef wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    tomteboda wrote: »
    SezxyStef wrote: »
    1st one is an abstract and is from 2002...almost 20 years old????

    I'm sure you are capable of finding the full article and reading it. I know I managed to do it. And I'm not sure why you have an issue with an article published 15 years ago. Unless time itself invalidates science.
    SezxyStef wrote: »
    and it doesn't address your assertion that bone size difference can account for 8+lbs in body weight variance of two people who are same gender, height and race.
    Except the first study does. And I didn't make any assertion in particular giving a number, you must be confusing me with another poster. HOWEVER...
    SezxyStef wrote: »
    and the 2nd one doesn't prove anything about your original assertion either...we know that Asians have a different BMI scale than we do and has nothing to do with your original argument or the original post...
    How is it that you can recognize interracial genetic frame differences that result in real health outcome differences related to BMI, but cannot accept that individual variation within populations is also real and significant?
    SezxyStef wrote: »
    My original assertion..BMI is a good measure for the average population and that there are few outliers in that population...and that it is not "bone size" that will account for people being categorized as overweight or obese it's fat.
    I don't argue that for an "average human being", whatever that is, BMI is a rough indicator of body fat. I do argue:
    1. that the cutoff of 25 is arbitrary and not supported by morbidity and morality data for all populations. The existence of separate recommendations for Asians is evidence.
    2. The BMI scale itself is flawed because it assumes a relationship of height to volume (mass) of h*h while volume is a cubic relationship. Being stochastically fitted for a height of 5' even, the error is linearly increasing with deviation from that height. This is not particularly controversial from a mathematics standing.
    3. As a matter of mathematical interest, if my bones alone, never mind the volume of everything else in me, account for 15% of my mass, and my friend's bones are 12% of hers, then exactly 7.6 lbs of our weight difference is just bones. Now, personally, I find it really stupid that if I gain 10 lbs I'm classified as "overweight" but she has to gain 35 lbs to be "overweight". Because my body is clearly larger in frame and muscle. That is a pretty good illustration of the arbitrary nature of BMI when applied to individuals not populations.
    4. Also on that matter, the fit of BMI to body fat is considered generally good... To one standard deviation. That's 68%. OK, great. That means if the population is normally distributed 32% are outliers.

    If you found the article why link in the abstract????

    2nd point you responded to me saying 8lbs of bone was a bit much imo with a negative assertion that it was possible based on you and your friend and there are 2 links...1 is an abstract that doesn't prove it and neither does the 2nd.

    No where did I say frame size of people was all the same...I said 8lbs of it was a bit much imo and that for those people claiming frame size keeps them in the overweight of bmi they were in denial...perhaps you have me confused with another poster.

    Now onto the meat of it.

    comparing 12% for your friend and 15% is flawed...apples to apples.

    and perhaps you are one of those individuals who is in denial because you are almost in the overweight category????and that is causing a bias in your argument...been there done that until I wasn't in the overweight category and still wearing a size 8 shoe...and still "big boned" but a hella lot less fat.

    I think accusing someone of being “in denial” about their body because you disagree with them on a point of them on a point of science is out of line and deserves an apology.

    I am not disagreeing on a point of science. She disagreed and argued that she is "bigger" because of bone size...I say no way...people who think that are in denial and are more fat than they want to admit.

    Point of science is this.

    BMI is a good measure for the average person (at least it is currently)
    12-15% of the body weight of a person is from bone no more no less.
    if you are in the overweight category for BMI it's not from bones...chances are you are overfat (unless an outlier who has exceptional muscle mass) and yes I will say that there are those who are outlier.

    This poster is not.

    ETA: so no apology will be forthcoming from me.

    That poster isn't overweight. She's within healthy range for BMI. You just moved the goalposts. She's near the top range for her BMI because she has a large frame.

    She's not in denial and yes, you do owe her an apology.

    1. I never said she didn't have a large frame.
    2. She contended bmi is not valid due to bone size which is invalid.
    3. I never said she was over weight I said she might be on the top end because she had more weight than she wants to admit aka denial.

    And I will not apologize for that.

    I will stand by my original statement that those who say bmi doesn't apply to them are most likely in denial as the outliers are not that common.

    People who are not educated in exercise science often use “bone size” as a substitute for “higher LBM”, since they are not familiar with other terminology. Fixating on their use of “bone size” because it is not precisely accurate confuses the issue

    I can say with 100% certainty that the number of “outliers” from the BMI ranges is at least 20%. I can also say with 100% certainty that the actual number of people “in denial” about their weight is less than 10%.

    Most of the people who have unrealistic expectations about their weight are those with “large frames” who think they can/should be able to reach the lower end of the BMI range for their height.

    nope and nope.

    First, you absolutely can't say that with any certainty. You say that from your gut, because it SEEMS that way to you. But I challenge you to find a study that supports either of those suppositions.

    You can "believe" them if you chose to. But there is a high probability that you are wrong on both counts.
    lemurcat12 wrote: »
    Here's one good comparison of BF% and BMI (given that the purpose of BMI is to act as a proxy for BF%): https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

    Key findings (note, this is for white people in Australia, there are likely race-based differences):

    *17.3% of women and 31.6% of men identified as obese according to BMI were not, based on BF%.
    *19.9% of women and 46.1% of men who were NOT obese by BMI actually were by BF%

    *BMI particularly underestimates adiposity in elderly men (aged 70 years and older), but also in young men (aged 20–29 years).

    That's different from another such study I recall seeing in the past, where it was much more likely to mischaracterize women as not obese when they were than obese when they were not. There was more mischaracterization for the overweight category in that one (this one focused on obesity measures only).

    Here you go

    This study deals ONLY with the overweight/obese boundary, and finds that people around that boundary are possibly on opposite sides depending on the measure. This seems entirely reasonable and expected.

    It doesn't deal with people falling in the "normal weight" category under either measure, at all. The study simply doesn't contain the data relevant to this discussion. The only way to even extrapolate "normal weight" numbers from this study is to sum the numbers given and subtract from 100%

    I have no issue conceding that some people who are merely "overweight" by bf% are obese by BMI, and visa-versa. But that is utterly irrelevant to the question of whether everybody can fit in the "normal weight" category.

    You claimed the 20% number was unsupported.

    Study supports 20% number.

    End of story.

    Addtitionally, you've incorrectly characterized the study, as it looked at all 4 categories
    Underweight
    Normal
    Overweight
    Obese.
  • jdlobb
    jdlobb Posts: 1,232 Member
    edited November 2017
    jdlobb wrote: »
    jdlobb wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    SezxyStef wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    tomteboda wrote: »
    SezxyStef wrote: »
    1st one is an abstract and is from 2002...almost 20 years old????

    I'm sure you are capable of finding the full article and reading it. I know I managed to do it. And I'm not sure why you have an issue with an article published 15 years ago. Unless time itself invalidates science.
    SezxyStef wrote: »
    and it doesn't address your assertion that bone size difference can account for 8+lbs in body weight variance of two people who are same gender, height and race.
    Except the first study does. And I didn't make any assertion in particular giving a number, you must be confusing me with another poster. HOWEVER...
    SezxyStef wrote: »
    and the 2nd one doesn't prove anything about your original assertion either...we know that Asians have a different BMI scale than we do and has nothing to do with your original argument or the original post...
    How is it that you can recognize interracial genetic frame differences that result in real health outcome differences related to BMI, but cannot accept that individual variation within populations is also real and significant?
    SezxyStef wrote: »
    My original assertion..BMI is a good measure for the average population and that there are few outliers in that population...and that it is not "bone size" that will account for people being categorized as overweight or obese it's fat.
    I don't argue that for an "average human being", whatever that is, BMI is a rough indicator of body fat. I do argue:
    1. that the cutoff of 25 is arbitrary and not supported by morbidity and morality data for all populations. The existence of separate recommendations for Asians is evidence.
    2. The BMI scale itself is flawed because it assumes a relationship of height to volume (mass) of h*h while volume is a cubic relationship. Being stochastically fitted for a height of 5' even, the error is linearly increasing with deviation from that height. This is not particularly controversial from a mathematics standing.
    3. As a matter of mathematical interest, if my bones alone, never mind the volume of everything else in me, account for 15% of my mass, and my friend's bones are 12% of hers, then exactly 7.6 lbs of our weight difference is just bones. Now, personally, I find it really stupid that if I gain 10 lbs I'm classified as "overweight" but she has to gain 35 lbs to be "overweight". Because my body is clearly larger in frame and muscle. That is a pretty good illustration of the arbitrary nature of BMI when applied to individuals not populations.
    4. Also on that matter, the fit of BMI to body fat is considered generally good... To one standard deviation. That's 68%. OK, great. That means if the population is normally distributed 32% are outliers.

    If you found the article why link in the abstract????

    2nd point you responded to me saying 8lbs of bone was a bit much imo with a negative assertion that it was possible based on you and your friend and there are 2 links...1 is an abstract that doesn't prove it and neither does the 2nd.

    No where did I say frame size of people was all the same...I said 8lbs of it was a bit much imo and that for those people claiming frame size keeps them in the overweight of bmi they were in denial...perhaps you have me confused with another poster.

    Now onto the meat of it.

    comparing 12% for your friend and 15% is flawed...apples to apples.

    and perhaps you are one of those individuals who is in denial because you are almost in the overweight category????and that is causing a bias in your argument...been there done that until I wasn't in the overweight category and still wearing a size 8 shoe...and still "big boned" but a hella lot less fat.

    I think accusing someone of being “in denial” about their body because you disagree with them on a point of them on a point of science is out of line and deserves an apology.

    I am not disagreeing on a point of science. She disagreed and argued that she is "bigger" because of bone size...I say no way...people who think that are in denial and are more fat than they want to admit.

    Point of science is this.

    BMI is a good measure for the average person (at least it is currently)
    12-15% of the body weight of a person is from bone no more no less.
    if you are in the overweight category for BMI it's not from bones...chances are you are overfat (unless an outlier who has exceptional muscle mass) and yes I will say that there are those who are outlier.

    This poster is not.

    ETA: so no apology will be forthcoming from me.

    That poster isn't overweight. She's within healthy range for BMI. You just moved the goalposts. She's near the top range for her BMI because she has a large frame.

    She's not in denial and yes, you do owe her an apology.

    1. I never said she didn't have a large frame.
    2. She contended bmi is not valid due to bone size which is invalid.
    3. I never said she was over weight I said she might be on the top end because she had more weight than she wants to admit aka denial.

    And I will not apologize for that.

    I will stand by my original statement that those who say bmi doesn't apply to them are most likely in denial as the outliers are not that common.

    People who are not educated in exercise science often use “bone size” as a substitute for “higher LBM”, since they are not familiar with other terminology. Fixating on their use of “bone size” because it is not precisely accurate confuses the issue

    I can say with 100% certainty that the number of “outliers” from the BMI ranges is at least 20%. I can also say with 100% certainty that the actual number of people “in denial” about their weight is less than 10%.

    Most of the people who have unrealistic expectations about their weight are those with “large frames” who think they can/should be able to reach the lower end of the BMI range for their height.

    nope and nope.

    First, you absolutely can't say that with any certainty. You say that from your gut, because it SEEMS that way to you. But I challenge you to find a study that supports either of those suppositions.

    You can "believe" them if you chose to. But there is a high probability that you are wrong on both counts.
    lemurcat12 wrote: »
    Here's one good comparison of BF% and BMI (given that the purpose of BMI is to act as a proxy for BF%): https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

    Key findings (note, this is for white people in Australia, there are likely race-based differences):

    *17.3% of women and 31.6% of men identified as obese according to BMI were not, based on BF%.
    *19.9% of women and 46.1% of men who were NOT obese by BMI actually were by BF%

    *BMI particularly underestimates adiposity in elderly men (aged 70 years and older), but also in young men (aged 20–29 years).

    That's different from another such study I recall seeing in the past, where it was much more likely to mischaracterize women as not obese when they were than obese when they were not. There was more mischaracterization for the overweight category in that one (this one focused on obesity measures only).

    Here you go

    This study deals ONLY with the overweight/obese boundary, and finds that people around that boundary are possibly on opposite sides depending on the measure. This seems entirely reasonable and expected.

    It doesn't deal with people falling in the "normal weight" category under either measure, at all. The study simply doesn't contain the data relevant to this discussion. The only way to even extrapolate "normal weight" numbers from this study is to sum the numbers given and subtract from 100%

    I have no issue conceding that some people who are merely "overweight" by bf% are obese by BMI, and visa-versa. But that is utterly irrelevant to the question of whether everybody can fit in the "normal weight" category.

    You claimed the 20% number was unsupported.

    Study supports 20% number.

    End of story.

    no. study only supports that 20% of people who are overweight or obese are the opposite under the other measure. It doesn't support that anybody who is overweight or obese under either measure is actually normal weight under the other.

    That data is not contained in this study, which does not deal with normal weight people as categorized by either measure, at all.

    what exactly does it matter if somebody is actually "obese" under BMI if they're only "overweight" by BF%? or visa versa? they're still not a healthy weight under either measure.
  • stanmann571
    stanmann571 Posts: 5,736 Member
    edited November 2017
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    SezxyStef wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    tomteboda wrote: »
    SezxyStef wrote: »
    1st one is an abstract and is from 2002...almost 20 years old????

    I'm sure you are capable of finding the full article and reading it. I know I managed to do it. And I'm not sure why you have an issue with an article published 15 years ago. Unless time itself invalidates science.
    SezxyStef wrote: »
    and it doesn't address your assertion that bone size difference can account for 8+lbs in body weight variance of two people who are same gender, height and race.
    Except the first study does. And I didn't make any assertion in particular giving a number, you must be confusing me with another poster. HOWEVER...
    SezxyStef wrote: »
    and the 2nd one doesn't prove anything about your original assertion either...we know that Asians have a different BMI scale than we do and has nothing to do with your original argument or the original post...
    How is it that you can recognize interracial genetic frame differences that result in real health outcome differences related to BMI, but cannot accept that individual variation within populations is also real and significant?
    SezxyStef wrote: »
    My original assertion..BMI is a good measure for the average population and that there are few outliers in that population...and that it is not "bone size" that will account for people being categorized as overweight or obese it's fat.
    I don't argue that for an "average human being", whatever that is, BMI is a rough indicator of body fat. I do argue:
    1. that the cutoff of 25 is arbitrary and not supported by morbidity and morality data for all populations. The existence of separate recommendations for Asians is evidence.
    2. The BMI scale itself is flawed because it assumes a relationship of height to volume (mass) of h*h while volume is a cubic relationship. Being stochastically fitted for a height of 5' even, the error is linearly increasing with deviation from that height. This is not particularly controversial from a mathematics standing.
    3. As a matter of mathematical interest, if my bones alone, never mind the volume of everything else in me, account for 15% of my mass, and my friend's bones are 12% of hers, then exactly 7.6 lbs of our weight difference is just bones. Now, personally, I find it really stupid that if I gain 10 lbs I'm classified as "overweight" but she has to gain 35 lbs to be "overweight". Because my body is clearly larger in frame and muscle. That is a pretty good illustration of the arbitrary nature of BMI when applied to individuals not populations.
    4. Also on that matter, the fit of BMI to body fat is considered generally good... To one standard deviation. That's 68%. OK, great. That means if the population is normally distributed 32% are outliers.

    If you found the article why link in the abstract????

    2nd point you responded to me saying 8lbs of bone was a bit much imo with a negative assertion that it was possible based on you and your friend and there are 2 links...1 is an abstract that doesn't prove it and neither does the 2nd.

    No where did I say frame size of people was all the same...I said 8lbs of it was a bit much imo and that for those people claiming frame size keeps them in the overweight of bmi they were in denial...perhaps you have me confused with another poster.

    Now onto the meat of it.

    comparing 12% for your friend and 15% is flawed...apples to apples.

    and perhaps you are one of those individuals who is in denial because you are almost in the overweight category????and that is causing a bias in your argument...been there done that until I wasn't in the overweight category and still wearing a size 8 shoe...and still "big boned" but a hella lot less fat.

    I think accusing someone of being “in denial” about their body because you disagree with them on a point of them on a point of science is out of line and deserves an apology.

    I am not disagreeing on a point of science. She disagreed and argued that she is "bigger" because of bone size...I say no way...people who think that are in denial and are more fat than they want to admit.

    Point of science is this.

    BMI is a good measure for the average person (at least it is currently)
    12-15% of the body weight of a person is from bone no more no less.
    if you are in the overweight category for BMI it's not from bones...chances are you are overfat (unless an outlier who has exceptional muscle mass) and yes I will say that there are those who are outlier.

    This poster is not.

    ETA: so no apology will be forthcoming from me.

    That poster isn't overweight. She's within healthy range for BMI. You just moved the goalposts. She's near the top range for her BMI because she has a large frame.

    She's not in denial and yes, you do owe her an apology.

    1. I never said she didn't have a large frame.
    2. She contended bmi is not valid due to bone size which is invalid.
    3. I never said she was over weight I said she might be on the top end because she had more weight than she wants to admit aka denial.

    And I will not apologize for that.

    I will stand by my original statement that those who say bmi doesn't apply to them are most likely in denial as the outliers are not that common.

    People who are not educated in exercise science often use “bone size” as a substitute for “higher LBM”, since they are not familiar with other terminology. Fixating on their use of “bone size” because it is not precisely accurate confuses the issue

    I can say with 100% certainty that the number of “outliers” from the BMI ranges is at least 20%. I can also say with 100% certainty that the actual number of people “in denial” about their weight is less than 10%.

    Most of the people who have unrealistic expectations about their weight are those with “large frames” who think they can/should be able to reach the lower end of the BMI range for their height.

    nope and nope.

    First, you absolutely can't say that with any certainty. You say that from your gut, because it SEEMS that way to you. But I challenge you to find a study that supports either of those suppositions.

    You can "believe" them if you chose to. But there is a high probability that you are wrong on both counts.
    lemurcat12 wrote: »
    Here's one good comparison of BF% and BMI (given that the purpose of BMI is to act as a proxy for BF%): https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

    Key findings (note, this is for white people in Australia, there are likely race-based differences):

    *17.3% of women and 31.6% of men identified as obese according to BMI were not, based on BF%.
    *19.9% of women and 46.1% of men who were NOT obese by BMI actually were by BF%

    *BMI particularly underestimates adiposity in elderly men (aged 70 years and older), but also in young men (aged 20–29 years).

    That's different from another such study I recall seeing in the past, where it was much more likely to mischaracterize women as not obese when they were than obese when they were not. There was more mischaracterization for the overweight category in that one (this one focused on obesity measures only).

    Here you go

    This study deals ONLY with the overweight/obese boundary, and finds that people around that boundary are possibly on opposite sides depending on the measure. This seems entirely reasonable and expected.

    It doesn't deal with people falling in the "normal weight" category under either measure, at all. The study simply doesn't contain the data relevant to this discussion. The only way to even extrapolate "normal weight" numbers from this study is to sum the numbers given and subtract from 100%

    I have no issue conceding that some people who are merely "overweight" by bf% are obese by BMI, and visa-versa. But that is utterly irrelevant to the question of whether everybody can fit in the "normal weight" category.

    You claimed the 20% number was unsupported.

    Study supports 20% number.

    End of story.

    no. study only supports that 20% of people who are overweight or obese are the opposite under the other measure. It doesn't support that anybody who is overweight or obese under either measure is actually normal weight under the other.

    That data is not contained in this study, which does not deal with normal weight people as categorized by either measure, at all.

    what exactly does it matter if somebody is actually "obese" under BMI if they're only "overweight" by BF%? or visa versa? they're still not a healthy weight under either measure.

    Of course it matters. If someone is "obese" by BMI, and thus believes he is 50 or 70 lbs overweight when in fact he's only overweight and 15-20 lbs above a healthy BF% that is a huge deal psychologically.
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6); agreement to within one category was observed for 98.7% men and 99.8% women. Whereas 82.7% of women classed as obese according to BMI were also identified as obese according to sex-and-age-specific %BF criteria, only 68.4% of men classed as obese by BMI were similarly classified by sex-and-age-specific %BF. On the other hand, 80.1% of women and 53.9% of men who were identified as obese according to sex-and-age-specific %BF criteria, had BMI ≥ 30.0 k/m2.

    If you get It wrong 30-45% of the time, You don't have a useful index.

    Worst part is the 30-45% of "healthy" BMI folks who are in fact over BF%.

  • jdlobb
    jdlobb Posts: 1,232 Member
    Additionally, this study argues EXACTLY the opposite of the point you people are trying to make. It finds that BMI actually pretty significantly UNDERESTIMATES the number of obese people compared to BF%.
  • jdlobb
    jdlobb Posts: 1,232 Member
    edited November 2017
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    SezxyStef wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    tomteboda wrote: »
    SezxyStef wrote: »
    1st one is an abstract and is from 2002...almost 20 years old????

    I'm sure you are capable of finding the full article and reading it. I know I managed to do it. And I'm not sure why you have an issue with an article published 15 years ago. Unless time itself invalidates science.
    SezxyStef wrote: »
    and it doesn't address your assertion that bone size difference can account for 8+lbs in body weight variance of two people who are same gender, height and race.
    Except the first study does. And I didn't make any assertion in particular giving a number, you must be confusing me with another poster. HOWEVER...
    SezxyStef wrote: »
    and the 2nd one doesn't prove anything about your original assertion either...we know that Asians have a different BMI scale than we do and has nothing to do with your original argument or the original post...
    How is it that you can recognize interracial genetic frame differences that result in real health outcome differences related to BMI, but cannot accept that individual variation within populations is also real and significant?
    SezxyStef wrote: »
    My original assertion..BMI is a good measure for the average population and that there are few outliers in that population...and that it is not "bone size" that will account for people being categorized as overweight or obese it's fat.
    I don't argue that for an "average human being", whatever that is, BMI is a rough indicator of body fat. I do argue:
    1. that the cutoff of 25 is arbitrary and not supported by morbidity and morality data for all populations. The existence of separate recommendations for Asians is evidence.
    2. The BMI scale itself is flawed because it assumes a relationship of height to volume (mass) of h*h while volume is a cubic relationship. Being stochastically fitted for a height of 5' even, the error is linearly increasing with deviation from that height. This is not particularly controversial from a mathematics standing.
    3. As a matter of mathematical interest, if my bones alone, never mind the volume of everything else in me, account for 15% of my mass, and my friend's bones are 12% of hers, then exactly 7.6 lbs of our weight difference is just bones. Now, personally, I find it really stupid that if I gain 10 lbs I'm classified as "overweight" but she has to gain 35 lbs to be "overweight". Because my body is clearly larger in frame and muscle. That is a pretty good illustration of the arbitrary nature of BMI when applied to individuals not populations.
    4. Also on that matter, the fit of BMI to body fat is considered generally good... To one standard deviation. That's 68%. OK, great. That means if the population is normally distributed 32% are outliers.

    If you found the article why link in the abstract????

    2nd point you responded to me saying 8lbs of bone was a bit much imo with a negative assertion that it was possible based on you and your friend and there are 2 links...1 is an abstract that doesn't prove it and neither does the 2nd.

    No where did I say frame size of people was all the same...I said 8lbs of it was a bit much imo and that for those people claiming frame size keeps them in the overweight of bmi they were in denial...perhaps you have me confused with another poster.

    Now onto the meat of it.

    comparing 12% for your friend and 15% is flawed...apples to apples.

    and perhaps you are one of those individuals who is in denial because you are almost in the overweight category????and that is causing a bias in your argument...been there done that until I wasn't in the overweight category and still wearing a size 8 shoe...and still "big boned" but a hella lot less fat.

    I think accusing someone of being “in denial” about their body because you disagree with them on a point of them on a point of science is out of line and deserves an apology.

    I am not disagreeing on a point of science. She disagreed and argued that she is "bigger" because of bone size...I say no way...people who think that are in denial and are more fat than they want to admit.

    Point of science is this.

    BMI is a good measure for the average person (at least it is currently)
    12-15% of the body weight of a person is from bone no more no less.
    if you are in the overweight category for BMI it's not from bones...chances are you are overfat (unless an outlier who has exceptional muscle mass) and yes I will say that there are those who are outlier.

    This poster is not.

    ETA: so no apology will be forthcoming from me.

    That poster isn't overweight. She's within healthy range for BMI. You just moved the goalposts. She's near the top range for her BMI because she has a large frame.

    She's not in denial and yes, you do owe her an apology.

    1. I never said she didn't have a large frame.
    2. She contended bmi is not valid due to bone size which is invalid.
    3. I never said she was over weight I said she might be on the top end because she had more weight than she wants to admit aka denial.

    And I will not apologize for that.

    I will stand by my original statement that those who say bmi doesn't apply to them are most likely in denial as the outliers are not that common.

    People who are not educated in exercise science often use “bone size” as a substitute for “higher LBM”, since they are not familiar with other terminology. Fixating on their use of “bone size” because it is not precisely accurate confuses the issue

    I can say with 100% certainty that the number of “outliers” from the BMI ranges is at least 20%. I can also say with 100% certainty that the actual number of people “in denial” about their weight is less than 10%.

    Most of the people who have unrealistic expectations about their weight are those with “large frames” who think they can/should be able to reach the lower end of the BMI range for their height.

    nope and nope.

    First, you absolutely can't say that with any certainty. You say that from your gut, because it SEEMS that way to you. But I challenge you to find a study that supports either of those suppositions.

    You can "believe" them if you chose to. But there is a high probability that you are wrong on both counts.
    lemurcat12 wrote: »
    Here's one good comparison of BF% and BMI (given that the purpose of BMI is to act as a proxy for BF%): https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

    Key findings (note, this is for white people in Australia, there are likely race-based differences):

    *17.3% of women and 31.6% of men identified as obese according to BMI were not, based on BF%.
    *19.9% of women and 46.1% of men who were NOT obese by BMI actually were by BF%

    *BMI particularly underestimates adiposity in elderly men (aged 70 years and older), but also in young men (aged 20–29 years).

    That's different from another such study I recall seeing in the past, where it was much more likely to mischaracterize women as not obese when they were than obese when they were not. There was more mischaracterization for the overweight category in that one (this one focused on obesity measures only).

    Here you go

    This study deals ONLY with the overweight/obese boundary, and finds that people around that boundary are possibly on opposite sides depending on the measure. This seems entirely reasonable and expected.

    It doesn't deal with people falling in the "normal weight" category under either measure, at all. The study simply doesn't contain the data relevant to this discussion. The only way to even extrapolate "normal weight" numbers from this study is to sum the numbers given and subtract from 100%

    I have no issue conceding that some people who are merely "overweight" by bf% are obese by BMI, and visa-versa. But that is utterly irrelevant to the question of whether everybody can fit in the "normal weight" category.

    You claimed the 20% number was unsupported.

    Study supports 20% number.

    End of story.

    no. study only supports that 20% of people who are overweight or obese are the opposite under the other measure. It doesn't support that anybody who is overweight or obese under either measure is actually normal weight under the other.

    That data is not contained in this study, which does not deal with normal weight people as categorized by either measure, at all.

    what exactly does it matter if somebody is actually "obese" under BMI if they're only "overweight" by BF%? or visa versa? they're still not a healthy weight under either measure.

    Of course it matters. If someone is "obese" by BMI, and thus believes he is 50 or 70 lbs overweight when in fact he's only overweight and 15-20 lbs above a healthy BF% that is a huge deal psychologically.

    lol wut

    and what about the people who believe they are only "overweight" when infact they're obese and need to lose a lot more than they think? the people who, btw, greatly outnumber your choice group, according to your cherry picked study.
  • jdlobb
    jdlobb Posts: 1,232 Member
    edited November 2017
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    SezxyStef wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    tomteboda wrote: »
    SezxyStef wrote: »
    1st one is an abstract and is from 2002...almost 20 years old????

    I'm sure you are capable of finding the full article and reading it. I know I managed to do it. And I'm not sure why you have an issue with an article published 15 years ago. Unless time itself invalidates science.
    SezxyStef wrote: »
    and it doesn't address your assertion that bone size difference can account for 8+lbs in body weight variance of two people who are same gender, height and race.
    Except the first study does. And I didn't make any assertion in particular giving a number, you must be confusing me with another poster. HOWEVER...
    SezxyStef wrote: »
    and the 2nd one doesn't prove anything about your original assertion either...we know that Asians have a different BMI scale than we do and has nothing to do with your original argument or the original post...
    How is it that you can recognize interracial genetic frame differences that result in real health outcome differences related to BMI, but cannot accept that individual variation within populations is also real and significant?
    SezxyStef wrote: »
    My original assertion..BMI is a good measure for the average population and that there are few outliers in that population...and that it is not "bone size" that will account for people being categorized as overweight or obese it's fat.
    I don't argue that for an "average human being", whatever that is, BMI is a rough indicator of body fat. I do argue:
    1. that the cutoff of 25 is arbitrary and not supported by morbidity and morality data for all populations. The existence of separate recommendations for Asians is evidence.
    2. The BMI scale itself is flawed because it assumes a relationship of height to volume (mass) of h*h while volume is a cubic relationship. Being stochastically fitted for a height of 5' even, the error is linearly increasing with deviation from that height. This is not particularly controversial from a mathematics standing.
    3. As a matter of mathematical interest, if my bones alone, never mind the volume of everything else in me, account for 15% of my mass, and my friend's bones are 12% of hers, then exactly 7.6 lbs of our weight difference is just bones. Now, personally, I find it really stupid that if I gain 10 lbs I'm classified as "overweight" but she has to gain 35 lbs to be "overweight". Because my body is clearly larger in frame and muscle. That is a pretty good illustration of the arbitrary nature of BMI when applied to individuals not populations.
    4. Also on that matter, the fit of BMI to body fat is considered generally good... To one standard deviation. That's 68%. OK, great. That means if the population is normally distributed 32% are outliers.

    If you found the article why link in the abstract????

    2nd point you responded to me saying 8lbs of bone was a bit much imo with a negative assertion that it was possible based on you and your friend and there are 2 links...1 is an abstract that doesn't prove it and neither does the 2nd.

    No where did I say frame size of people was all the same...I said 8lbs of it was a bit much imo and that for those people claiming frame size keeps them in the overweight of bmi they were in denial...perhaps you have me confused with another poster.

    Now onto the meat of it.

    comparing 12% for your friend and 15% is flawed...apples to apples.

    and perhaps you are one of those individuals who is in denial because you are almost in the overweight category????and that is causing a bias in your argument...been there done that until I wasn't in the overweight category and still wearing a size 8 shoe...and still "big boned" but a hella lot less fat.

    I think accusing someone of being “in denial” about their body because you disagree with them on a point of them on a point of science is out of line and deserves an apology.

    I am not disagreeing on a point of science. She disagreed and argued that she is "bigger" because of bone size...I say no way...people who think that are in denial and are more fat than they want to admit.

    Point of science is this.

    BMI is a good measure for the average person (at least it is currently)
    12-15% of the body weight of a person is from bone no more no less.
    if you are in the overweight category for BMI it's not from bones...chances are you are overfat (unless an outlier who has exceptional muscle mass) and yes I will say that there are those who are outlier.

    This poster is not.

    ETA: so no apology will be forthcoming from me.

    That poster isn't overweight. She's within healthy range for BMI. You just moved the goalposts. She's near the top range for her BMI because she has a large frame.

    She's not in denial and yes, you do owe her an apology.

    1. I never said she didn't have a large frame.
    2. She contended bmi is not valid due to bone size which is invalid.
    3. I never said she was over weight I said she might be on the top end because she had more weight than she wants to admit aka denial.

    And I will not apologize for that.

    I will stand by my original statement that those who say bmi doesn't apply to them are most likely in denial as the outliers are not that common.

    People who are not educated in exercise science often use “bone size” as a substitute for “higher LBM”, since they are not familiar with other terminology. Fixating on their use of “bone size” because it is not precisely accurate confuses the issue

    I can say with 100% certainty that the number of “outliers” from the BMI ranges is at least 20%. I can also say with 100% certainty that the actual number of people “in denial” about their weight is less than 10%.

    Most of the people who have unrealistic expectations about their weight are those with “large frames” who think they can/should be able to reach the lower end of the BMI range for their height.

    nope and nope.

    First, you absolutely can't say that with any certainty. You say that from your gut, because it SEEMS that way to you. But I challenge you to find a study that supports either of those suppositions.

    You can "believe" them if you chose to. But there is a high probability that you are wrong on both counts.
    lemurcat12 wrote: »
    Here's one good comparison of BF% and BMI (given that the purpose of BMI is to act as a proxy for BF%): https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

    Key findings (note, this is for white people in Australia, there are likely race-based differences):

    *17.3% of women and 31.6% of men identified as obese according to BMI were not, based on BF%.
    *19.9% of women and 46.1% of men who were NOT obese by BMI actually were by BF%

    *BMI particularly underestimates adiposity in elderly men (aged 70 years and older), but also in young men (aged 20–29 years).

    That's different from another such study I recall seeing in the past, where it was much more likely to mischaracterize women as not obese when they were than obese when they were not. There was more mischaracterization for the overweight category in that one (this one focused on obesity measures only).

    Here you go

    This study deals ONLY with the overweight/obese boundary, and finds that people around that boundary are possibly on opposite sides depending on the measure. This seems entirely reasonable and expected.

    It doesn't deal with people falling in the "normal weight" category under either measure, at all. The study simply doesn't contain the data relevant to this discussion. The only way to even extrapolate "normal weight" numbers from this study is to sum the numbers given and subtract from 100%

    I have no issue conceding that some people who are merely "overweight" by bf% are obese by BMI, and visa-versa. But that is utterly irrelevant to the question of whether everybody can fit in the "normal weight" category.

    You claimed the 20% number was unsupported.

    Study supports 20% number.

    End of story.

    no. study only supports that 20% of people who are overweight or obese are the opposite under the other measure. It doesn't support that anybody who is overweight or obese under either measure is actually normal weight under the other.

    That data is not contained in this study, which does not deal with normal weight people as categorized by either measure, at all.

    what exactly does it matter if somebody is actually "obese" under BMI if they're only "overweight" by BF%? or visa versa? they're still not a healthy weight under either measure.

    Of course it matters. If someone is "obese" by BMI, and thus believes he is 50 or 70 lbs overweight when in fact he's only overweight and 15-20 lbs above a healthy BF% that is a huge deal psychologically.
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6); agreement to within one category was observed for 98.7% men and 99.8% women. Whereas 82.7% of women classed as obese according to BMI were also identified as obese according to sex-and-age-specific %BF criteria, only 68.4% of men classed as obese by BMI were similarly classified by sex-and-age-specific %BF. On the other hand, 80.1% of women and 53.9% of men who were identified as obese according to sex-and-age-specific %BF criteria, had BMI ≥ 30.0 k/m2.

    If you get It wrong 30-45% of the time, You don't have a useful index.

    Worst part is the 30-45% of "healthy" BMI folks who are in fact over BF%.

    and you get it wrong AGAIN.

    For some reason you're assuming that the %of people not "obese" are "healthy weight." But that' snot supported by their methodology. As the first part of your quote says, 99.8% of women are correct within 1 category. Meaning the vast, vast, VAST majority of those incorrectly categorized as "obese" are actually merely "overweight." which is STILL not "healthy weight".

    Read more closely.

    "not obese" simply means "overweight". not healthy weight. stop thinking it does.
  • stanmann571
    stanmann571 Posts: 5,736 Member
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    SezxyStef wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    tomteboda wrote: »
    SezxyStef wrote: »
    1st one is an abstract and is from 2002...almost 20 years old????

    I'm sure you are capable of finding the full article and reading it. I know I managed to do it. And I'm not sure why you have an issue with an article published 15 years ago. Unless time itself invalidates science.
    SezxyStef wrote: »
    and it doesn't address your assertion that bone size difference can account for 8+lbs in body weight variance of two people who are same gender, height and race.
    Except the first study does. And I didn't make any assertion in particular giving a number, you must be confusing me with another poster. HOWEVER...
    SezxyStef wrote: »
    and the 2nd one doesn't prove anything about your original assertion either...we know that Asians have a different BMI scale than we do and has nothing to do with your original argument or the original post...
    How is it that you can recognize interracial genetic frame differences that result in real health outcome differences related to BMI, but cannot accept that individual variation within populations is also real and significant?
    SezxyStef wrote: »
    My original assertion..BMI is a good measure for the average population and that there are few outliers in that population...and that it is not "bone size" that will account for people being categorized as overweight or obese it's fat.
    I don't argue that for an "average human being", whatever that is, BMI is a rough indicator of body fat. I do argue:
    1. that the cutoff of 25 is arbitrary and not supported by morbidity and morality data for all populations. The existence of separate recommendations for Asians is evidence.
    2. The BMI scale itself is flawed because it assumes a relationship of height to volume (mass) of h*h while volume is a cubic relationship. Being stochastically fitted for a height of 5' even, the error is linearly increasing with deviation from that height. This is not particularly controversial from a mathematics standing.
    3. As a matter of mathematical interest, if my bones alone, never mind the volume of everything else in me, account for 15% of my mass, and my friend's bones are 12% of hers, then exactly 7.6 lbs of our weight difference is just bones. Now, personally, I find it really stupid that if I gain 10 lbs I'm classified as "overweight" but she has to gain 35 lbs to be "overweight". Because my body is clearly larger in frame and muscle. That is a pretty good illustration of the arbitrary nature of BMI when applied to individuals not populations.
    4. Also on that matter, the fit of BMI to body fat is considered generally good... To one standard deviation. That's 68%. OK, great. That means if the population is normally distributed 32% are outliers.

    If you found the article why link in the abstract????

    2nd point you responded to me saying 8lbs of bone was a bit much imo with a negative assertion that it was possible based on you and your friend and there are 2 links...1 is an abstract that doesn't prove it and neither does the 2nd.

    No where did I say frame size of people was all the same...I said 8lbs of it was a bit much imo and that for those people claiming frame size keeps them in the overweight of bmi they were in denial...perhaps you have me confused with another poster.

    Now onto the meat of it.

    comparing 12% for your friend and 15% is flawed...apples to apples.

    and perhaps you are one of those individuals who is in denial because you are almost in the overweight category????and that is causing a bias in your argument...been there done that until I wasn't in the overweight category and still wearing a size 8 shoe...and still "big boned" but a hella lot less fat.

    I think accusing someone of being “in denial” about their body because you disagree with them on a point of them on a point of science is out of line and deserves an apology.

    I am not disagreeing on a point of science. She disagreed and argued that she is "bigger" because of bone size...I say no way...people who think that are in denial and are more fat than they want to admit.

    Point of science is this.

    BMI is a good measure for the average person (at least it is currently)
    12-15% of the body weight of a person is from bone no more no less.
    if you are in the overweight category for BMI it's not from bones...chances are you are overfat (unless an outlier who has exceptional muscle mass) and yes I will say that there are those who are outlier.

    This poster is not.

    ETA: so no apology will be forthcoming from me.

    That poster isn't overweight. She's within healthy range for BMI. You just moved the goalposts. She's near the top range for her BMI because she has a large frame.

    She's not in denial and yes, you do owe her an apology.

    1. I never said she didn't have a large frame.
    2. She contended bmi is not valid due to bone size which is invalid.
    3. I never said she was over weight I said she might be on the top end because she had more weight than she wants to admit aka denial.

    And I will not apologize for that.

    I will stand by my original statement that those who say bmi doesn't apply to them are most likely in denial as the outliers are not that common.

    People who are not educated in exercise science often use “bone size” as a substitute for “higher LBM”, since they are not familiar with other terminology. Fixating on their use of “bone size” because it is not precisely accurate confuses the issue

    I can say with 100% certainty that the number of “outliers” from the BMI ranges is at least 20%. I can also say with 100% certainty that the actual number of people “in denial” about their weight is less than 10%.

    Most of the people who have unrealistic expectations about their weight are those with “large frames” who think they can/should be able to reach the lower end of the BMI range for their height.

    nope and nope.

    First, you absolutely can't say that with any certainty. You say that from your gut, because it SEEMS that way to you. But I challenge you to find a study that supports either of those suppositions.

    You can "believe" them if you chose to. But there is a high probability that you are wrong on both counts.
    lemurcat12 wrote: »
    Here's one good comparison of BF% and BMI (given that the purpose of BMI is to act as a proxy for BF%): https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

    Key findings (note, this is for white people in Australia, there are likely race-based differences):

    *17.3% of women and 31.6% of men identified as obese according to BMI were not, based on BF%.
    *19.9% of women and 46.1% of men who were NOT obese by BMI actually were by BF%

    *BMI particularly underestimates adiposity in elderly men (aged 70 years and older), but also in young men (aged 20–29 years).

    That's different from another such study I recall seeing in the past, where it was much more likely to mischaracterize women as not obese when they were than obese when they were not. There was more mischaracterization for the overweight category in that one (this one focused on obesity measures only).

    Here you go

    This study deals ONLY with the overweight/obese boundary, and finds that people around that boundary are possibly on opposite sides depending on the measure. This seems entirely reasonable and expected.

    It doesn't deal with people falling in the "normal weight" category under either measure, at all. The study simply doesn't contain the data relevant to this discussion. The only way to even extrapolate "normal weight" numbers from this study is to sum the numbers given and subtract from 100%

    I have no issue conceding that some people who are merely "overweight" by bf% are obese by BMI, and visa-versa. But that is utterly irrelevant to the question of whether everybody can fit in the "normal weight" category.

    You claimed the 20% number was unsupported.

    Study supports 20% number.

    End of story.

    no. study only supports that 20% of people who are overweight or obese are the opposite under the other measure. It doesn't support that anybody who is overweight or obese under either measure is actually normal weight under the other.

    That data is not contained in this study, which does not deal with normal weight people as categorized by either measure, at all.

    what exactly does it matter if somebody is actually "obese" under BMI if they're only "overweight" by BF%? or visa versa? they're still not a healthy weight under either measure.

    Of course it matters. If someone is "obese" by BMI, and thus believes he is 50 or 70 lbs overweight when in fact he's only overweight and 15-20 lbs above a healthy BF% that is a huge deal psychologically.
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6); agreement to within one category was observed for 98.7% men and 99.8% women. Whereas 82.7% of women classed as obese according to BMI were also identified as obese according to sex-and-age-specific %BF criteria, only 68.4% of men classed as obese by BMI were similarly classified by sex-and-age-specific %BF. On the other hand, 80.1% of women and 53.9% of men who were identified as obese according to sex-and-age-specific %BF criteria, had BMI ≥ 30.0 k/m2.

    If you get It wrong 30-45% of the time, You don't have a useful index.

    Worst part is the 30-45% of "healthy" BMI folks who are in fact over BF%.

    and you get it wrong AGAIN.

    For some reason you're assuming that the %of people not "obese" are "healthy weight." But that' snot supported by their methodology. As the first part of your quote says, 99.8% of women are correct within 1 category. Meaning the vast, vast, VAST majority of those incorrectly categorized as "obese" are actually merely "overweight." which is STILL not "healthy weight".

    Read more closely.

    "not obese" simply means "overweight". not healthy weight. stop thinking it does.

    It also applies to Overweight and normal weight.

    Read it again
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6); agreement to within one category was observed for 98.7% men and 99.8% women.


    Wrong 37.4% of the time... in every direction.

    On the other hand, 80.1% of women and 53.9% of men who were identified as obese according to sex-and-age-specific %BF criteria, had BMI ≥ 30.0 k/m2.
    46.1% of obese men were not.

    Yes, most of them were overweight not normal weight.

    But, Normal weight were also Overweight and underweight
    Underweight were also normal weight
    Overweight were Normal weight and obese.

    The reality is that it's probably worse than the study portrays not better.
  • jdlobb
    jdlobb Posts: 1,232 Member
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    SezxyStef wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    tomteboda wrote: »
    SezxyStef wrote: »
    1st one is an abstract and is from 2002...almost 20 years old????

    I'm sure you are capable of finding the full article and reading it. I know I managed to do it. And I'm not sure why you have an issue with an article published 15 years ago. Unless time itself invalidates science.
    SezxyStef wrote: »
    and it doesn't address your assertion that bone size difference can account for 8+lbs in body weight variance of two people who are same gender, height and race.
    Except the first study does. And I didn't make any assertion in particular giving a number, you must be confusing me with another poster. HOWEVER...
    SezxyStef wrote: »
    and the 2nd one doesn't prove anything about your original assertion either...we know that Asians have a different BMI scale than we do and has nothing to do with your original argument or the original post...
    How is it that you can recognize interracial genetic frame differences that result in real health outcome differences related to BMI, but cannot accept that individual variation within populations is also real and significant?
    SezxyStef wrote: »
    My original assertion..BMI is a good measure for the average population and that there are few outliers in that population...and that it is not "bone size" that will account for people being categorized as overweight or obese it's fat.
    I don't argue that for an "average human being", whatever that is, BMI is a rough indicator of body fat. I do argue:
    1. that the cutoff of 25 is arbitrary and not supported by morbidity and morality data for all populations. The existence of separate recommendations for Asians is evidence.
    2. The BMI scale itself is flawed because it assumes a relationship of height to volume (mass) of h*h while volume is a cubic relationship. Being stochastically fitted for a height of 5' even, the error is linearly increasing with deviation from that height. This is not particularly controversial from a mathematics standing.
    3. As a matter of mathematical interest, if my bones alone, never mind the volume of everything else in me, account for 15% of my mass, and my friend's bones are 12% of hers, then exactly 7.6 lbs of our weight difference is just bones. Now, personally, I find it really stupid that if I gain 10 lbs I'm classified as "overweight" but she has to gain 35 lbs to be "overweight". Because my body is clearly larger in frame and muscle. That is a pretty good illustration of the arbitrary nature of BMI when applied to individuals not populations.
    4. Also on that matter, the fit of BMI to body fat is considered generally good... To one standard deviation. That's 68%. OK, great. That means if the population is normally distributed 32% are outliers.

    If you found the article why link in the abstract????

    2nd point you responded to me saying 8lbs of bone was a bit much imo with a negative assertion that it was possible based on you and your friend and there are 2 links...1 is an abstract that doesn't prove it and neither does the 2nd.

    No where did I say frame size of people was all the same...I said 8lbs of it was a bit much imo and that for those people claiming frame size keeps them in the overweight of bmi they were in denial...perhaps you have me confused with another poster.

    Now onto the meat of it.

    comparing 12% for your friend and 15% is flawed...apples to apples.

    and perhaps you are one of those individuals who is in denial because you are almost in the overweight category????and that is causing a bias in your argument...been there done that until I wasn't in the overweight category and still wearing a size 8 shoe...and still "big boned" but a hella lot less fat.

    I think accusing someone of being “in denial” about their body because you disagree with them on a point of them on a point of science is out of line and deserves an apology.

    I am not disagreeing on a point of science. She disagreed and argued that she is "bigger" because of bone size...I say no way...people who think that are in denial and are more fat than they want to admit.

    Point of science is this.

    BMI is a good measure for the average person (at least it is currently)
    12-15% of the body weight of a person is from bone no more no less.
    if you are in the overweight category for BMI it's not from bones...chances are you are overfat (unless an outlier who has exceptional muscle mass) and yes I will say that there are those who are outlier.

    This poster is not.

    ETA: so no apology will be forthcoming from me.

    That poster isn't overweight. She's within healthy range for BMI. You just moved the goalposts. She's near the top range for her BMI because she has a large frame.

    She's not in denial and yes, you do owe her an apology.

    1. I never said she didn't have a large frame.
    2. She contended bmi is not valid due to bone size which is invalid.
    3. I never said she was over weight I said she might be on the top end because she had more weight than she wants to admit aka denial.

    And I will not apologize for that.

    I will stand by my original statement that those who say bmi doesn't apply to them are most likely in denial as the outliers are not that common.

    People who are not educated in exercise science often use “bone size” as a substitute for “higher LBM”, since they are not familiar with other terminology. Fixating on their use of “bone size” because it is not precisely accurate confuses the issue

    I can say with 100% certainty that the number of “outliers” from the BMI ranges is at least 20%. I can also say with 100% certainty that the actual number of people “in denial” about their weight is less than 10%.

    Most of the people who have unrealistic expectations about their weight are those with “large frames” who think they can/should be able to reach the lower end of the BMI range for their height.

    nope and nope.

    First, you absolutely can't say that with any certainty. You say that from your gut, because it SEEMS that way to you. But I challenge you to find a study that supports either of those suppositions.

    You can "believe" them if you chose to. But there is a high probability that you are wrong on both counts.
    lemurcat12 wrote: »
    Here's one good comparison of BF% and BMI (given that the purpose of BMI is to act as a proxy for BF%): https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

    Key findings (note, this is for white people in Australia, there are likely race-based differences):

    *17.3% of women and 31.6% of men identified as obese according to BMI were not, based on BF%.
    *19.9% of women and 46.1% of men who were NOT obese by BMI actually were by BF%

    *BMI particularly underestimates adiposity in elderly men (aged 70 years and older), but also in young men (aged 20–29 years).

    That's different from another such study I recall seeing in the past, where it was much more likely to mischaracterize women as not obese when they were than obese when they were not. There was more mischaracterization for the overweight category in that one (this one focused on obesity measures only).

    Here you go

    This study deals ONLY with the overweight/obese boundary, and finds that people around that boundary are possibly on opposite sides depending on the measure. This seems entirely reasonable and expected.

    It doesn't deal with people falling in the "normal weight" category under either measure, at all. The study simply doesn't contain the data relevant to this discussion. The only way to even extrapolate "normal weight" numbers from this study is to sum the numbers given and subtract from 100%

    I have no issue conceding that some people who are merely "overweight" by bf% are obese by BMI, and visa-versa. But that is utterly irrelevant to the question of whether everybody can fit in the "normal weight" category.

    You claimed the 20% number was unsupported.

    Study supports 20% number.

    End of story.

    no. study only supports that 20% of people who are overweight or obese are the opposite under the other measure. It doesn't support that anybody who is overweight or obese under either measure is actually normal weight under the other.

    That data is not contained in this study, which does not deal with normal weight people as categorized by either measure, at all.

    what exactly does it matter if somebody is actually "obese" under BMI if they're only "overweight" by BF%? or visa versa? they're still not a healthy weight under either measure.

    Of course it matters. If someone is "obese" by BMI, and thus believes he is 50 or 70 lbs overweight when in fact he's only overweight and 15-20 lbs above a healthy BF% that is a huge deal psychologically.
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6); agreement to within one category was observed for 98.7% men and 99.8% women. Whereas 82.7% of women classed as obese according to BMI were also identified as obese according to sex-and-age-specific %BF criteria, only 68.4% of men classed as obese by BMI were similarly classified by sex-and-age-specific %BF. On the other hand, 80.1% of women and 53.9% of men who were identified as obese according to sex-and-age-specific %BF criteria, had BMI ≥ 30.0 k/m2.

    If you get It wrong 30-45% of the time, You don't have a useful index.

    Worst part is the 30-45% of "healthy" BMI folks who are in fact over BF%.

    and you get it wrong AGAIN.

    For some reason you're assuming that the %of people not "obese" are "healthy weight." But that' snot supported by their methodology. As the first part of your quote says, 99.8% of women are correct within 1 category. Meaning the vast, vast, VAST majority of those incorrectly categorized as "obese" are actually merely "overweight." which is STILL not "healthy weight".

    Read more closely.

    "not obese" simply means "overweight". not healthy weight. stop thinking it does.

    It also applies to Overweight and normal weight.

    Read it again
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6); agreement to within one category was observed for 98.7% men and 99.8% women.


    Wrong 37.4% of the time... in every direction.

    On the other hand, 80.1% of women and 53.9% of men who were identified as obese according to sex-and-age-specific %BF criteria, had BMI ≥ 30.0 k/m2.
    46.1% of obese men were not.

    Yes, most of them were overweight not normal weight.

    But, Normal weight were also Overweight and underweight
    Underweight were also normal weight
    Overweight were Normal weight and obese.

    The reality is that it's probably worse than the study portrays not better.

    what the actual *kitten*. You're literally quoting things that refute what you say.
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6);

    so 37.4% of men and 26.1% of women were in the wrong category. fact. reasonable.

    WHAT YOU ARE MISSING
    agreement to within one category was observed for 98.7% men and 99.8% women.

    Only 1.3% of men and 0.2% of women are in a category OTHER than the one immediately higher or lower than the one predicted by BMI.

    The paper does not contain ANY data on the number of people categorized as "ideal weight" by BMI that are actually overweight, or the number categorized as "overweight" by BMI that are actually "ideal weight" according to BF%.

    The paper simply does not contain that.

    It is ONLY concerned with the overweight/obese boundary, as it is specifically talking about miscategorization (both directions) of OBESE people, and only 1.3% of men and 0.2% are miscategorized by more than 1 category.

    Overweight is NOT healthy weight. Obese people categorized as overweight are STILL NOT A HEALTHY WEIGHT.
  • stanmann571
    stanmann571 Posts: 5,736 Member
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    jdlobb wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    SezxyStef wrote: »
    Azdak wrote: »
    SezxyStef wrote: »
    tomteboda wrote: »
    SezxyStef wrote: »
    1st one is an abstract and is from 2002...almost 20 years old????

    I'm sure you are capable of finding the full article and reading it. I know I managed to do it. And I'm not sure why you have an issue with an article published 15 years ago. Unless time itself invalidates science.
    SezxyStef wrote: »
    and it doesn't address your assertion that bone size difference can account for 8+lbs in body weight variance of two people who are same gender, height and race.
    Except the first study does. And I didn't make any assertion in particular giving a number, you must be confusing me with another poster. HOWEVER...
    SezxyStef wrote: »
    and the 2nd one doesn't prove anything about your original assertion either...we know that Asians have a different BMI scale than we do and has nothing to do with your original argument or the original post...
    How is it that you can recognize interracial genetic frame differences that result in real health outcome differences related to BMI, but cannot accept that individual variation within populations is also real and significant?
    SezxyStef wrote: »
    My original assertion..BMI is a good measure for the average population and that there are few outliers in that population...and that it is not "bone size" that will account for people being categorized as overweight or obese it's fat.
    I don't argue that for an "average human being", whatever that is, BMI is a rough indicator of body fat. I do argue:
    1. that the cutoff of 25 is arbitrary and not supported by morbidity and morality data for all populations. The existence of separate recommendations for Asians is evidence.
    2. The BMI scale itself is flawed because it assumes a relationship of height to volume (mass) of h*h while volume is a cubic relationship. Being stochastically fitted for a height of 5' even, the error is linearly increasing with deviation from that height. This is not particularly controversial from a mathematics standing.
    3. As a matter of mathematical interest, if my bones alone, never mind the volume of everything else in me, account for 15% of my mass, and my friend's bones are 12% of hers, then exactly 7.6 lbs of our weight difference is just bones. Now, personally, I find it really stupid that if I gain 10 lbs I'm classified as "overweight" but she has to gain 35 lbs to be "overweight". Because my body is clearly larger in frame and muscle. That is a pretty good illustration of the arbitrary nature of BMI when applied to individuals not populations.
    4. Also on that matter, the fit of BMI to body fat is considered generally good... To one standard deviation. That's 68%. OK, great. That means if the population is normally distributed 32% are outliers.

    If you found the article why link in the abstract????

    2nd point you responded to me saying 8lbs of bone was a bit much imo with a negative assertion that it was possible based on you and your friend and there are 2 links...1 is an abstract that doesn't prove it and neither does the 2nd.

    No where did I say frame size of people was all the same...I said 8lbs of it was a bit much imo and that for those people claiming frame size keeps them in the overweight of bmi they were in denial...perhaps you have me confused with another poster.

    Now onto the meat of it.

    comparing 12% for your friend and 15% is flawed...apples to apples.

    and perhaps you are one of those individuals who is in denial because you are almost in the overweight category????and that is causing a bias in your argument...been there done that until I wasn't in the overweight category and still wearing a size 8 shoe...and still "big boned" but a hella lot less fat.

    I think accusing someone of being “in denial” about their body because you disagree with them on a point of them on a point of science is out of line and deserves an apology.

    I am not disagreeing on a point of science. She disagreed and argued that she is "bigger" because of bone size...I say no way...people who think that are in denial and are more fat than they want to admit.

    Point of science is this.

    BMI is a good measure for the average person (at least it is currently)
    12-15% of the body weight of a person is from bone no more no less.
    if you are in the overweight category for BMI it's not from bones...chances are you are overfat (unless an outlier who has exceptional muscle mass) and yes I will say that there are those who are outlier.

    This poster is not.

    ETA: so no apology will be forthcoming from me.

    That poster isn't overweight. She's within healthy range for BMI. You just moved the goalposts. She's near the top range for her BMI because she has a large frame.

    She's not in denial and yes, you do owe her an apology.

    1. I never said she didn't have a large frame.
    2. She contended bmi is not valid due to bone size which is invalid.
    3. I never said she was over weight I said she might be on the top end because she had more weight than she wants to admit aka denial.

    And I will not apologize for that.

    I will stand by my original statement that those who say bmi doesn't apply to them are most likely in denial as the outliers are not that common.

    People who are not educated in exercise science often use “bone size” as a substitute for “higher LBM”, since they are not familiar with other terminology. Fixating on their use of “bone size” because it is not precisely accurate confuses the issue

    I can say with 100% certainty that the number of “outliers” from the BMI ranges is at least 20%. I can also say with 100% certainty that the actual number of people “in denial” about their weight is less than 10%.

    Most of the people who have unrealistic expectations about their weight are those with “large frames” who think they can/should be able to reach the lower end of the BMI range for their height.

    nope and nope.

    First, you absolutely can't say that with any certainty. You say that from your gut, because it SEEMS that way to you. But I challenge you to find a study that supports either of those suppositions.

    You can "believe" them if you chose to. But there is a high probability that you are wrong on both counts.
    lemurcat12 wrote: »
    Here's one good comparison of BF% and BMI (given that the purpose of BMI is to act as a proxy for BF%): https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

    Key findings (note, this is for white people in Australia, there are likely race-based differences):

    *17.3% of women and 31.6% of men identified as obese according to BMI were not, based on BF%.
    *19.9% of women and 46.1% of men who were NOT obese by BMI actually were by BF%

    *BMI particularly underestimates adiposity in elderly men (aged 70 years and older), but also in young men (aged 20–29 years).

    That's different from another such study I recall seeing in the past, where it was much more likely to mischaracterize women as not obese when they were than obese when they were not. There was more mischaracterization for the overweight category in that one (this one focused on obesity measures only).

    Here you go

    This study deals ONLY with the overweight/obese boundary, and finds that people around that boundary are possibly on opposite sides depending on the measure. This seems entirely reasonable and expected.

    It doesn't deal with people falling in the "normal weight" category under either measure, at all. The study simply doesn't contain the data relevant to this discussion. The only way to even extrapolate "normal weight" numbers from this study is to sum the numbers given and subtract from 100%

    I have no issue conceding that some people who are merely "overweight" by bf% are obese by BMI, and visa-versa. But that is utterly irrelevant to the question of whether everybody can fit in the "normal weight" category.

    You claimed the 20% number was unsupported.

    Study supports 20% number.

    End of story.

    no. study only supports that 20% of people who are overweight or obese are the opposite under the other measure. It doesn't support that anybody who is overweight or obese under either measure is actually normal weight under the other.

    That data is not contained in this study, which does not deal with normal weight people as categorized by either measure, at all.

    what exactly does it matter if somebody is actually "obese" under BMI if they're only "overweight" by BF%? or visa versa? they're still not a healthy weight under either measure.

    Of course it matters. If someone is "obese" by BMI, and thus believes he is 50 or 70 lbs overweight when in fact he's only overweight and 15-20 lbs above a healthy BF% that is a huge deal psychologically.
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6); agreement to within one category was observed for 98.7% men and 99.8% women. Whereas 82.7% of women classed as obese according to BMI were also identified as obese according to sex-and-age-specific %BF criteria, only 68.4% of men classed as obese by BMI were similarly classified by sex-and-age-specific %BF. On the other hand, 80.1% of women and 53.9% of men who were identified as obese according to sex-and-age-specific %BF criteria, had BMI ≥ 30.0 k/m2.

    If you get It wrong 30-45% of the time, You don't have a useful index.

    Worst part is the 30-45% of "healthy" BMI folks who are in fact over BF%.

    and you get it wrong AGAIN.

    For some reason you're assuming that the %of people not "obese" are "healthy weight." But that' snot supported by their methodology. As the first part of your quote says, 99.8% of women are correct within 1 category. Meaning the vast, vast, VAST majority of those incorrectly categorized as "obese" are actually merely "overweight." which is STILL not "healthy weight".

    Read more closely.

    "not obese" simply means "overweight". not healthy weight. stop thinking it does.

    It also applies to Overweight and normal weight.

    Read it again
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6); agreement to within one category was observed for 98.7% men and 99.8% women.


    Wrong 37.4% of the time... in every direction.

    On the other hand, 80.1% of women and 53.9% of men who were identified as obese according to sex-and-age-specific %BF criteria, had BMI ≥ 30.0 k/m2.
    46.1% of obese men were not.

    Yes, most of them were overweight not normal weight.

    But, Normal weight were also Overweight and underweight
    Underweight were also normal weight
    Overweight were Normal weight and obese.

    The reality is that it's probably worse than the study portrays not better.

    what the actual *kitten*. You're literally quoting things that refute what you say.
    There was exact agreement using sex-and-age-specific %BF and BMI criteria for categorising underweight, ideal weight, overweight and obese groups for 62.6% men (κ = 0.4) and 73.9% women (κ = 0.6);

    so 37.4% of men and 26.1% of women were in the wrong category. fact. reasonable.

    WHAT YOU ARE MISSING
    agreement to within one category was observed for 98.7% men and 99.8% women.

    Only 1.3% of men and 0.2% of women are in a category OTHER than the one immediately higher or lower than the one predicted by BMI.

    The paper does not contain ANY data on the number of people categorized as "ideal weight" by BMI that are actually overweight, or the number categorized as "overweight" by BMI that are actually "ideal weight" according to BF%.

    The paper simply does not contain that.

    It does, I just don't have time to wrangle it out of the tables.
  • lemurcat12
    lemurcat12 Posts: 30,886 Member
    edited November 2017
    The study says that three-quarters of women and less than two-thirds of the men had agreement between the category that BMI would put them in and that BF% would put them in. The vast majority were just one category off. More (but not overwhelmingly more) were misclassified as overweight when they were obese than obese when they were overweight, but it happened in both directions. I think we can conclude from that that there is a not insubstantial number of people who would be classified as overweight by BMI but normal weight/not overfat by BF%, and that more of them would be men than women.

    I don't understand this insistence that it cannot happen, that everyone should be in the healthy BMI range.

    (And for the record I have no personal involvement in this, the BMI scale works fine for me, my preference is to be around 21-22 BMI at max.)
  • jdlobb
    jdlobb Posts: 1,232 Member
    edited November 2017
    Let's tie a bow on this. The paper being used to attack BMI as being too "mean" to lean people, shows no such thing. In fact, from the authors' own conclusions
    Paradoxically, our study also suggests that the BMI markedly underestimated adiposity in young men (aged 20–29 years). It seems likely that for this group, body fat contributes more, and lean tissue less, to body weight than in other groups. While the reasons for this remain unclear, we might speculate that the fat-to-lean tissue mass ratio is disproportionately high as a result of unhealthy lifestyle choices including sedentary behaviour and poor nutrition. Differences in body composition might also be related to an increasing prevalence of growth hormone deficiency with increasing age, resulting in loss of lean tissue and increases in body fat [17]. These findings have public health implications, as the prevalence of adult obesity as described by the BMI, may be underestimated at a population level, particularly among men.

    Both the BMI and %BF identify weight or fat mass relative to the whole body, but this has been conceptualized differently for the two indices. The BMI expresses body weight (kg) relative to stature (height, m2) and it should be noted that adjustment for height in this index is suboptimal [18]. The second order polynomial relationship between BMI and %BF [5] is partly explained by the relative relationship of body fat mass to total body weight; increments in body fat mass result in diminishing increments in %BF. Furthermore, accumulation of body fat in healthy bodies is generally accompanied by a compensatory response from the musculoskeletal system, acting through mechanoreceptors in muscle and bone, as it adapts to better cope with the increasing mechanical load [19]. Adipokines also act as regulatory messengers between adipocytes in fat deposits, muscle [20] and bone [21, 22]. However, with excessive accumulation of body fat, the increased loading could exceed compensatory musculoskeletal responses thereby altering the proportions of fat, lean and bone issue. As a consequence, increases in BMI could reflect increased weight-for-height yet mask changes in body composition. Considering the obesity epidemic, a more accurate indicator of body fatness is required to better assess obesity-related health risks.

    1. In young males (the group most likely to think they're "too muscular for BMI" they found that BMI significantly under estimated fat. That BMI was in fact too generous.

    2. They further explain that one of the reasons obese people are only "overweight" by BF% is precisely because a lifetime of obesity triggers more bone and muscle to grow. A point I remember having made REPEATEDLY here in this thread and others.


    Again, for the n-th time, the paper doesn't in any way, in any part, in the data, the discussion, or the conclusions, make any statements about "normal weight" people. It is specifically analyzing and discussing OBESE people. And because the study found that 3 standard deviations of individuals fit within 1 category of their BMI predicted category, we can thus infer that the overwhelming, by an order of magnitude, number of people that fall in the OBESE category in EITHER MEASURE, are NOT healthy weight UNDER EITHER MEASURE.

    Read the damn paper people. Don't just skim it. This paper does not help the case that BMI is a bad tool for predicting someone's ideal weight, only that it is a bad tool for predicting extreme obesity, and that's because it doesn't consider enough people to be fat.
  • stanmann571
    stanmann571 Posts: 5,736 Member
    jdlobb wrote: »
    Let's tie a bow on this. The paper being used to attack BMI as being too "mean" to lean people, shows no such thing. In fact, from the authors' own conclusions
    Paradoxically, our study also suggests that the BMI markedly underestimated adiposity in young men (aged 20–29 years). It seems likely that for this group, body fat contributes more, and lean tissue less, to body weight than in other groups. While the reasons for this remain unclear, we might speculate that the fat-to-lean tissue mass ratio is disproportionately high as a result of unhealthy lifestyle choices including sedentary behaviour and poor nutrition. Differences in body composition might also be related to an increasing prevalence of growth hormone deficiency with increasing age, resulting in loss of lean tissue and increases in body fat [17]. These findings have public health implications, as the prevalence of adult obesity as described by the BMI, may be underestimated at a population level, particularly among men.

    Both the BMI and %BF identify weight or fat mass relative to the whole body, but this has been conceptualized differently for the two indices. The BMI expresses body weight (kg) relative to stature (height, m2) and it should be noted that adjustment for height in this index is suboptimal [18]. The second order polynomial relationship between BMI and %BF [5] is partly explained by the relative relationship of body fat mass to total body weight; increments in body fat mass result in diminishing increments in %BF. Furthermore, accumulation of body fat in healthy bodies is generally accompanied by a compensatory response from the musculoskeletal system, acting through mechanoreceptors in muscle and bone, as it adapts to better cope with the increasing mechanical load [19]. Adipokines also act as regulatory messengers between adipocytes in fat deposits, muscle [20] and bone [21, 22]. However, with excessive accumulation of body fat, the increased loading could exceed compensatory musculoskeletal responses thereby altering the proportions of fat, lean and bone issue. As a consequence, increases in BMI could reflect increased weight-for-height yet mask changes in body composition. Considering the obesity epidemic, a more accurate indicator of body fatness is required to better assess obesity-related health risks.

    1. In young males (the group most likely to think they're "too muscular for BMI" they found that BMI significantly under estimated fat. That BMI was in fact too generous.

    2. They further explain that one of the reasons obese people are only "overweight" by BF% is precisely because a lifetime of obesity triggers more bone and muscle to grow. A point I remember having made REPEATEDLY here in this thread and others.


    Again, for the n-th time, the paper doesn't in any way, in any part, in the data, the discussion, or the conclusions, make any statements about "normal weight" people. It is specifically analyzing and discussing OBESE people. And because the study found that 3 standard deviations of individuals fit within 1 category of their BMI predicted category, we can thus infer that the overwhelming, by an order of magnitude, number of people that fall in the OBESE category in EITHER MEASURE, are NOT healthy weight UNDER EITHER MEASURE.

    Read the damn paper people. Don't just skim it. This paper does not help the case that BMI is a bad tool for predicting someone's ideal weight, only that it is a bad tool for predicting extreme obesity, and that's because it doesn't consider enough people to be fat.

    The information you're claiming isn't there is in chart 4. As I said before I don't have the time to wrangle the numbers.

    But your persistent assertion that the data isn't there is incorrect.

    As you said.

    Read the *KITTEN* paper. don't just skim it.
  • lemurcat12
    lemurcat12 Posts: 30,886 Member
    jdlobb wrote: »
    Let's tie a bow on this. The paper being used to attack BMI as being too "mean" to lean people, shows no such thing.

    I'm the one who posted it originally. I did, because I was surprised that the number misidentified as obese when they were not was so high, particularly for women. I was already aware that many were misidentified as not obese or overweight when they were, and have said that.

    It was not posted to show BMI was "too mean" to lean people; that's your imagination.

    As I read stanman's later citation of it, it was in response to your claim that no one could show that a meaningful number of people were misidentified, or misidentified as obese when they are not, and it does show that. It shows that BMI and BF% do not always line up (often do not) and in some non insignificant percentage BMI indicates that they are in a higher fat category than BF% would say. You were (as I read you) denying this.

    I quoted already the part about people in many cases being fatter than BMI says too. This gotcha thing is totally fantasized on your part.
    Read the damn paper people. Don't just skim it. This paper does not help the case that BMI is a bad tool for predicting someone's ideal weight, only that it is a bad tool for predicting extreme obesity, and that's because it doesn't consider enough people to be fat.

    As stated before, it shows that BMI has limits in determining whether someone is overweight or obese by BF%, that other measures may be more helpful. Which is all anyone has claimed.

    And no, it absolutely does not show that it is a bad tool for predicting extreme obesity (or only extreme obesity). 25% of women and over 33% of men were in the wrong category. We don't know the precise breakdown (without someone getting it from the tables), but it looks like it's roughly half (slightly less) of the miscategorized that BMI makes fatter than reality and half that it makes less fat (slightly more than half).

    Why is it so important to you to insist that BMI works perfectly when the evidence is that it's an okay starting tool and good for population measures but not a perfect proxy for BF% for many?
  • jdlobb
    jdlobb Posts: 1,232 Member
    jdlobb wrote: »
    Let's tie a bow on this. The paper being used to attack BMI as being too "mean" to lean people, shows no such thing. In fact, from the authors' own conclusions
    Paradoxically, our study also suggests that the BMI markedly underestimated adiposity in young men (aged 20–29 years). It seems likely that for this group, body fat contributes more, and lean tissue less, to body weight than in other groups. While the reasons for this remain unclear, we might speculate that the fat-to-lean tissue mass ratio is disproportionately high as a result of unhealthy lifestyle choices including sedentary behaviour and poor nutrition. Differences in body composition might also be related to an increasing prevalence of growth hormone deficiency with increasing age, resulting in loss of lean tissue and increases in body fat [17]. These findings have public health implications, as the prevalence of adult obesity as described by the BMI, may be underestimated at a population level, particularly among men.

    Both the BMI and %BF identify weight or fat mass relative to the whole body, but this has been conceptualized differently for the two indices. The BMI expresses body weight (kg) relative to stature (height, m2) and it should be noted that adjustment for height in this index is suboptimal [18]. The second order polynomial relationship between BMI and %BF [5] is partly explained by the relative relationship of body fat mass to total body weight; increments in body fat mass result in diminishing increments in %BF. Furthermore, accumulation of body fat in healthy bodies is generally accompanied by a compensatory response from the musculoskeletal system, acting through mechanoreceptors in muscle and bone, as it adapts to better cope with the increasing mechanical load [19]. Adipokines also act as regulatory messengers between adipocytes in fat deposits, muscle [20] and bone [21, 22]. However, with excessive accumulation of body fat, the increased loading could exceed compensatory musculoskeletal responses thereby altering the proportions of fat, lean and bone issue. As a consequence, increases in BMI could reflect increased weight-for-height yet mask changes in body composition. Considering the obesity epidemic, a more accurate indicator of body fatness is required to better assess obesity-related health risks.

    1. In young males (the group most likely to think they're "too muscular for BMI" they found that BMI significantly under estimated fat. That BMI was in fact too generous.

    2. They further explain that one of the reasons obese people are only "overweight" by BF% is precisely because a lifetime of obesity triggers more bone and muscle to grow. A point I remember having made REPEATEDLY here in this thread and others.


    Again, for the n-th time, the paper doesn't in any way, in any part, in the data, the discussion, or the conclusions, make any statements about "normal weight" people. It is specifically analyzing and discussing OBESE people. And because the study found that 3 standard deviations of individuals fit within 1 category of their BMI predicted category, we can thus infer that the overwhelming, by an order of magnitude, number of people that fall in the OBESE category in EITHER MEASURE, are NOT healthy weight UNDER EITHER MEASURE.

    Read the damn paper people. Don't just skim it. This paper does not help the case that BMI is a bad tool for predicting someone's ideal weight, only that it is a bad tool for predicting extreme obesity, and that's because it doesn't consider enough people to be fat.

    The information you're claiming isn't there is in chart 4. As I said before I don't have the time to wrangle the numbers.

    But your persistent assertion that the data isn't there is incorrect.

    As you said.

    Read the *KITTEN* paper. don't just skim it.

    nope. it does not.

    It shows the number of people in non-ideal weight categories under both methods. It says absolutely nothing about which of those people were miscategorized. It only shows the differences in how many people are in each method, it doesn't show which direction the miscategorized people fell.

    It also doesn't include the number in "Ideal weight" under either category, although you could calculate this category by subtracting the other categories.

    How often do you read academic papers?
  • jdlobb
    jdlobb Posts: 1,232 Member
    because I have nothing better to do apparently. I went ahead and calculated the percent of people in "ideal weight" under each category more men.

    Please notice that for most age groups far FEWER people are categorized as "ideal weight" under BF% than under BMI, meaning BMI is too generous. Which is what the paper argued.

    4pppgsiqtuz8.jpg
  • stanmann571
    stanmann571 Posts: 5,736 Member
    jdlobb wrote: »
    jdlobb wrote: »
    Let's tie a bow on this. The paper being used to attack BMI as being too "mean" to lean people, shows no such thing. In fact, from the authors' own conclusions
    Paradoxically, our study also suggests that the BMI markedly underestimated adiposity in young men (aged 20–29 years). It seems likely that for this group, body fat contributes more, and lean tissue less, to body weight than in other groups. While the reasons for this remain unclear, we might speculate that the fat-to-lean tissue mass ratio is disproportionately high as a result of unhealthy lifestyle choices including sedentary behaviour and poor nutrition. Differences in body composition might also be related to an increasing prevalence of growth hormone deficiency with increasing age, resulting in loss of lean tissue and increases in body fat [17]. These findings have public health implications, as the prevalence of adult obesity as described by the BMI, may be underestimated at a population level, particularly among men.

    Both the BMI and %BF identify weight or fat mass relative to the whole body, but this has been conceptualized differently for the two indices. The BMI expresses body weight (kg) relative to stature (height, m2) and it should be noted that adjustment for height in this index is suboptimal [18]. The second order polynomial relationship between BMI and %BF [5] is partly explained by the relative relationship of body fat mass to total body weight; increments in body fat mass result in diminishing increments in %BF. Furthermore, accumulation of body fat in healthy bodies is generally accompanied by a compensatory response from the musculoskeletal system, acting through mechanoreceptors in muscle and bone, as it adapts to better cope with the increasing mechanical load [19]. Adipokines also act as regulatory messengers between adipocytes in fat deposits, muscle [20] and bone [21, 22]. However, with excessive accumulation of body fat, the increased loading could exceed compensatory musculoskeletal responses thereby altering the proportions of fat, lean and bone issue. As a consequence, increases in BMI could reflect increased weight-for-height yet mask changes in body composition. Considering the obesity epidemic, a more accurate indicator of body fatness is required to better assess obesity-related health risks.

    1. In young males (the group most likely to think they're "too muscular for BMI" they found that BMI significantly under estimated fat. That BMI was in fact too generous.

    2. They further explain that one of the reasons obese people are only "overweight" by BF% is precisely because a lifetime of obesity triggers more bone and muscle to grow. A point I remember having made REPEATEDLY here in this thread and others.


    Again, for the n-th time, the paper doesn't in any way, in any part, in the data, the discussion, or the conclusions, make any statements about "normal weight" people. It is specifically analyzing and discussing OBESE people. And because the study found that 3 standard deviations of individuals fit within 1 category of their BMI predicted category, we can thus infer that the overwhelming, by an order of magnitude, number of people that fall in the OBESE category in EITHER MEASURE, are NOT healthy weight UNDER EITHER MEASURE.

    Read the damn paper people. Don't just skim it. This paper does not help the case that BMI is a bad tool for predicting someone's ideal weight, only that it is a bad tool for predicting extreme obesity, and that's because it doesn't consider enough people to be fat.

    The information you're claiming isn't there is in chart 4. As I said before I don't have the time to wrangle the numbers.

    But your persistent assertion that the data isn't there is incorrect.

    As you said.

    Read the *KITTEN* paper. don't just skim it.

    nope. it does not.

    It shows the number of people in non-ideal weight categories under both methods. It says absolutely nothing about which of those people were miscategorized. It only shows the differences in how many people are in each method, it doesn't show which direction the miscategorized people fell.

    It also doesn't include the number in "Ideal weight" under either category, although you could calculate this category by subtracting the other categories.

    How often do you read academic papers?

    It's ok, most people aren't very good at applied math and statistics.

    Like I said above, It can be done, I just don't have the time.
  • jdlobb
    jdlobb Posts: 1,232 Member
    lemurcat12 wrote: »
    jdlobb wrote: »
    Let's tie a bow on this. The paper being used to attack BMI as being too "mean" to lean people, shows no such thing.

    I'm the one who posted it originally. I did, because I was surprised that the number misidentified as obese when they were not was so high, particularly for women. I was already aware that many were misidentified as not obese or overweight when they were, and have said that.

    It was not posted to show BMI was "too mean" to lean people; that's your imagination.

    As I read stanman's later citation of it, it was in response to your claim that no one could show that a meaningful number of people were misidentified, or misidentified as obese when they are not, and it does show that. It shows that BMI and BF% do not always line up (often do not) and in some non insignificant percentage BMI indicates that they are in a higher fat category than BF% would say. You were (as I read you) denying this.

    I quoted already the part about people in many cases being fatter than BMI says too. This gotcha thing is totally fantasized on your part.
    Read the damn paper people. Don't just skim it. This paper does not help the case that BMI is a bad tool for predicting someone's ideal weight, only that it is a bad tool for predicting extreme obesity, and that's because it doesn't consider enough people to be fat.

    As stated before, it shows that BMI has limits in determining whether someone is overweight or obese by BF%, that other measures may be more helpful. Which is all anyone has claimed.

    And no, it absolutely does not show that it is a bad tool for predicting extreme obesity (or only extreme obesity). 25% of women and over 33% of men were in the wrong category. We don't know the precise breakdown (without someone getting it from the tables), but it looks like it's roughly half (slightly less) of the miscategorized that BMI makes fatter than reality and half that it makes less fat (slightly more than half).

    Why is it so important to you to insist that BMI works perfectly when the evidence is that it's an okay starting tool and good for population measures but not a perfect proxy for BF% for many?

    for the n+1-th time.

    miscategorizing "overweight" vs "obese" is STILL NOT A HEALTHY WEIGHT.

    Still

    not

    healthy

    weight

    The claim was made that more than 20% of people think they're not healthy weight, when they are, or visa versa.

    The data in THIS PAPER does not back up that hypothesis. It doesn't come close. It only establishes that >20% of fat people are either more or less fat under one tool or the other. It does present any data or conclusions about what % of fat people aren't actually fat, or what percentage of not fat people are actually fat.

    stanman was wrong to post it as evidence to respond to my comment, because it contains NO SUCH EVIDENCE
  • jdlobb
    jdlobb Posts: 1,232 Member
    f-it, heres for men and women, the whole table 4, with Ideal Weight percentages calculated.

    BMI is more forgiving than BF% for both men and women for the majority of age groups

    pgf8g71y283l.jpg
  • lemurcat12
    lemurcat12 Posts: 30,886 Member
    jdlobb wrote: »
    lemurcat12 wrote: »
    jdlobb wrote: »
    Let's tie a bow on this. The paper being used to attack BMI as being too "mean" to lean people, shows no such thing.

    I'm the one who posted it originally. I did, because I was surprised that the number misidentified as obese when they were not was so high, particularly for women. I was already aware that many were misidentified as not obese or overweight when they were, and have said that.

    It was not posted to show BMI was "too mean" to lean people; that's your imagination.

    As I read stanman's later citation of it, it was in response to your claim that no one could show that a meaningful number of people were misidentified, or misidentified as obese when they are not, and it does show that. It shows that BMI and BF% do not always line up (often do not) and in some non insignificant percentage BMI indicates that they are in a higher fat category than BF% would say. You were (as I read you) denying this.

    I quoted already the part about people in many cases being fatter than BMI says too. This gotcha thing is totally fantasized on your part.
    Read the damn paper people. Don't just skim it. This paper does not help the case that BMI is a bad tool for predicting someone's ideal weight, only that it is a bad tool for predicting extreme obesity, and that's because it doesn't consider enough people to be fat.

    As stated before, it shows that BMI has limits in determining whether someone is overweight or obese by BF%, that other measures may be more helpful. Which is all anyone has claimed.

    And no, it absolutely does not show that it is a bad tool for predicting extreme obesity (or only extreme obesity). 25% of women and over 33% of men were in the wrong category. We don't know the precise breakdown (without someone getting it from the tables), but it looks like it's roughly half (slightly less) of the miscategorized that BMI makes fatter than reality and half that it makes less fat (slightly more than half).

    Why is it so important to you to insist that BMI works perfectly when the evidence is that it's an okay starting tool and good for population measures but not a perfect proxy for BF% for many?

    for the n+1-th time.

    miscategorizing "overweight" vs "obese" is STILL NOT A HEALTHY WEIGHT.

    Yes, everyone knows that. Again, 75% of women and less than 66% of men, of all categories, were in the wrong category. Almost all were just one off. That means there are people classified as overweight who are not, by BF%. That's what you (oddly) keep saying is not true.

    BMI is a fine measure for most people and for populations, but for an individual it can be wrong, and there are better measures. Period.
  • jdlobb
    jdlobb Posts: 1,232 Member
    edited November 2017
    lemurcat12 wrote: »
    jdlobb wrote: »
    lemurcat12 wrote: »
    jdlobb wrote: »
    Let's tie a bow on this. The paper being used to attack BMI as being too "mean" to lean people, shows no such thing.

    I'm the one who posted it originally. I did, because I was surprised that the number misidentified as obese when they were not was so high, particularly for women. I was already aware that many were misidentified as not obese or overweight when they were, and have said that.

    It was not posted to show BMI was "too mean" to lean people; that's your imagination.

    As I read stanman's later citation of it, it was in response to your claim that no one could show that a meaningful number of people were misidentified, or misidentified as obese when they are not, and it does show that. It shows that BMI and BF% do not always line up (often do not) and in some non insignificant percentage BMI indicates that they are in a higher fat category than BF% would say. You were (as I read you) denying this.

    I quoted already the part about people in many cases being fatter than BMI says too. This gotcha thing is totally fantasized on your part.
    Read the damn paper people. Don't just skim it. This paper does not help the case that BMI is a bad tool for predicting someone's ideal weight, only that it is a bad tool for predicting extreme obesity, and that's because it doesn't consider enough people to be fat.

    As stated before, it shows that BMI has limits in determining whether someone is overweight or obese by BF%, that other measures may be more helpful. Which is all anyone has claimed.

    And no, it absolutely does not show that it is a bad tool for predicting extreme obesity (or only extreme obesity). 25% of women and over 33% of men were in the wrong category. We don't know the precise breakdown (without someone getting it from the tables), but it looks like it's roughly half (slightly less) of the miscategorized that BMI makes fatter than reality and half that it makes less fat (slightly more than half).

    Why is it so important to you to insist that BMI works perfectly when the evidence is that it's an okay starting tool and good for population measures but not a perfect proxy for BF% for many?

    for the n+1-th time.

    miscategorizing "overweight" vs "obese" is STILL NOT A HEALTHY WEIGHT.

    Yes, everyone knows that. Again, 75% of women and less than 66% of men, of all categories, were in the wrong category. Almost all were just one off. That means there are people classified as overweight who are not, by BF%. That's what you (oddly) keep saying is not true.

    BMI is a fine measure for most people and for populations, but for an individual it can be wrong, and there are better measures. Period.

    I'm not saying this is not true, it is obviously true. What I am pointing out is that

    1. the paper does not contain the relevant data to know how many people meet this criteria
    2. given that the number of ideal weight people falls, in some cases considerably, when moving from BMI to BF% it is quite reasonable to assume that the number of overweight people who are ideal weight under BF% is likely quite low, and almost certainly far less than 20%.


    The paper is arguing, quite effectively, the BMI is an ineffective tool because it is most likely to UNDERESTIMATE how fat somebody it.

    Meaning if the average person is trying to predict an "ideal weight" then BMI might actually be too generous, and they may need to aim lower than the upper bound of "ideal weight" for their height.

    Keeping that in mind. BMI "ideal weight" is overly broad, which, mathematically, means an even LARGER portion of the population should be able to fit within it's "normal weight" category, and some of those will STILL be overfat.

    So you're right. there ARE better measures, because BMI isn't strict enough.