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How do we judge a healthy weight range? BMI is no longer valid?

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  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
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    BillMcKay1 wrote: »
    We get it. You are a genetic freak that blows BMI into invalidity....


    You don't get it. I'm -not- a genetic freak. The invalidity of BMI as a personal indicator is because there is a large percentage of the population who are outside of BMI predicted norms, without being freaks.
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
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    stevencloser wrote: »
    There was. It was even linked earlier.
    It showed more people have too much fat while at a normal BMI than people with unproblematic amounts of bodyfat who are above normal BMI.
    Any other arguments?


    So the study showed BMI is a poor screening tool for individuals because it will miss a bunch of people who should be flagged, as well as flagging many who shouldn't be.

    If anything, the higher numbers of over-fat people with "healthy" BMI supports my position that BMI charts promote low muscle mass, because if BMI says you're good, but in reality you are above safe fat percentages then you are deficient in muscle by default.
  • coreyreichle
    coreyreichle Posts: 1,039 Member
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    MarkusDarwath wrote: »
    coreyreichle wrote: »
    There's nothing wrong with citing experts on the subject.

    There is if someone is presenting reasoning against the generally accepted postion, and the argument in favor amounts to frequently repeated platitudes attributed to the "experts" without presenting the reasoning and data in support.

    The data in support of BMI shows it has a reasonably good correlation with overall health risks in large population samples (except that the category delineations are off and the "healthy" range should actually be 20 to 27). The idea that said relationship continues to hold on the individual level is basically an extrapolation that ignores some basic mathematical facts regarding large-sample averages. What is need are studies of the relationship between BMI and BF% on the individual level, if one is to validate or invalidate BMI as an estimate of personal fatness.

    That data is available, and it has been done. In fact, BMI works for about 97% of the population as a measure of healthy weight ranges, and in fact, was adjusted a couple of years back to bring it more in line with that.
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
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    Packerjohn wrote: »
    You mentioned lifting weights in high school. Are you currently lifting on a regular basis?

    No. At the moment, doing physical work is my only regular exercise.
    You mentioned wearing size 36 pants with a 47 inch waist measuremnt. This would indicate lack of muscle in the legs and hips which are the biggest muscles in the body. I think there would need to be much more muscle in these areas ton get to 34% given current height and weight.

    The manufacturer's waist size is not a fair estimation. They are "relaxed fit" and I'm pretty sure I've stretched them out quite a bit. My actual measurement at the waist band (taken just now in just underwear) is 43" and my widest point hip measurement is 44.5"
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
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    coreyreichle wrote: »
    That data is available, and it has been done. In fact, BMI works for about 97% of the population as a measure of healthy weight ranges, and in fact, was adjusted a couple of years back to bring it more in line with that.

    Can you cite a source for that 97%, please?

    The only recent adjustment I'm aware of is when they lowered the "healthy" range from 27 to 25. This was done in response to the addition of studies in more countries where they previously had come mostly from North America and Europe. A significant portion of the new additions came from Asia, in particular Japan. The problem with this is that when you take an average from genetically diverse cultures, and then include some others that are mostly genetically homogeneous, it is going to skew the end result. The final average may be more accurate in regard to the global aggregate, but it is going to be less accurate with regard to the specific cultures making up the average.

  • Gallowmere1984
    Gallowmere1984 Posts: 6,626 Member
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    MarkusDarwath wrote: »
    coreyreichle wrote: »
    That data is available, and it has been done. In fact, BMI works for about 97% of the population as a measure of healthy weight ranges, and in fact, was adjusted a couple of years back to bring it more in line with that.

    Can you cite a source for that 97%, please?

    The only recent adjustment I'm aware of is when they lowered the "healthy" range from 27 to 25. This was done in response to the addition of studies in more countries where they previously had come mostly from North America and Europe. A significant portion of the new additions came from Asia, in particular Japan. The problem with this is that when you take an average from genetically diverse cultures, and then include some others that are mostly genetically homogeneous, it is going to skew the end result. The final average may be more accurate in regard to the global aggregate, but it is going to be less accurate with regard to the specific cultures making up the average.

    This is true, though I'd find it pretty hilarious if they were to use Samoans to counterbalance the Japanese.
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
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    coreyreichle wrote: »

    How do you know what you're comfortable with?

    Because I want more strength than what I currently have, and you don't increase strength by reducing muscle mass.
    Shocker: The picture in my profile was me +10 lbs. My neck has actually remained constant, regardless of my weight. In fact, your neck typically does, until you start getting to the top end of obesity, and the only way to get a "large neck" while being a healthy weight is specifically working for muscle hypertrophy in those regions.

    My neck is 18". It was 19" when I was 281#, dropped to 18" over 6 weeks and has stayed the same in the 8 weeks since. That 1" difference looks noticeably more lean in the mirror.
    Actually, it does, because you keep claiming you don't have much lean mass to lose.

    You are misreading. I didn't say I -couldn't- lose lean mass. I said I would -have to- in order to get under 25 BMI at my desired 15% body fat. I also said there is no good reason to do so, and also that my current lean mass, as judged by physical strength and the muscle% given by my BIA scale, is already less than what I want.
    Bottom line: You are not a special snowflake.

    I completely agree
    Unless you are purposefully working on muscle hypertrophy, for years, you don't need to worry about being a BMI outlier.

    This is where I disagree. There is a certain percentage of people who can only reach "healthy" BMI by either achieving a BF% that qualifies as athletic or better or by dropping lean mass to an -unnecessarily- low level. That level may or may not be unhealthy, but it puts them at a below average percent of muscle mass. In my opinion, that percentage of people is far higher than the promoters of BMI let on.

    Granted, for there to even be an average percent of muscle (or an average range of percentages) some people are going to naturally fall below and some above. So having a below average muscle percentage isn't always a bad thing, and for some it's actually a positive, such as distance runners who's ideal would be to minimize all mass and retain only the muscle needed to move their body weight. However, just because being below average muscle percentage isn't always bad, does not automatically make it a good thing either. Outside of specific performance goals, there is no health benefit to being below average muscle% in terms of metabolic disease risk, and it could even be a negative with regard to injury resistance.

    Using BMI <25 as a target for body weight skews toward those who are in the bottom half of muscle mass percentage. For those in the upper half (which just for clarity, includes half of those who are 'normal' and not hyper muscular) BMI based weight goals often fail to be simultaneously realistic and desirable. There's no sense in setting a goal that is only one or the other, when using BF% instead is more likely to produce a target that is both.

  • tomteboda
    tomteboda Posts: 2,171 Member
    edited August 2016
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    coreyreichle wrote: »
    That data is available, and it has been done. In fact, BMI works for about 97% of the population as a measure of healthy weight ranges, and in fact, was adjusted a couple of years back to bring it more in line with that.

    The WHO says their confidence interval is 95% for the world as a whole but subpopulations within display significant variance in the mean. They use a 2 standard deviations for overweight and underweight. 3 standard deviations for extreme underweight.

  • SapiensPisces
    SapiensPisces Posts: 1,001 Member
    edited August 2016
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    For me, I think the BMI range is reasonable. I have an average build (not excessive muscle/fat ratio or other way around). My goals are based heavily on BMI numbers. It really depends on what your goals are and how you're built.
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
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    Just to throw this out there, I just had blood and urine samples taken this past Saturday and got my results back yesterday. My A1C is down to 5.8, which would be considered "pre-diabetic" if I hadn't already been diagnosed. (normal is <5.7 and prediabetes is 5.7 - 6.4) My fasting glucose was high for that particular morning, but everything else, including all cholesterol numbers and trigycerides were solidly within expected ranges.
    It seems my health risk is dropping much faster than my BMI.
  • BillMcKay1
    BillMcKay1 Posts: 315 Member
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    You are misreading. I didn't say I -couldn't- lose lean mass. I said I would -have to- in order to get under 25 BMI at my desired 15% body fat. I also said there is no good reason to do so, and also that my current lean mass, as judged by physical strength and the muscle% given by my BIA scale, is already less than what I want.

    Your BIA scale is off and highly inaccurate. They all are. You are over estimating your current lean mass. I would invest in a DXA scan if you are that certain.

  • robininfl
    robininfl Posts: 1,137 Member
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    MarkusDarwath wrote: »
    Just to throw this out there, I just had blood and urine samples taken this past Saturday and got my results back yesterday. My A1C is down to 5.8, which would be considered "pre-diabetic" if I hadn't already been diagnosed. (normal is <5.7 and prediabetes is 5.7 - 6.4) My fasting glucose was high for that particular morning, but everything else, including all cholesterol numbers and trigycerides were solidly within expected ranges.
    It seems my health risk is dropping much faster than my BMI.

    Congratulations!

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