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 BMI is no longer valid?

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Replies

  • MarkusDarwath
    MarkusDarwath Posts: 393 Member

    Because it takes about 2 seconds to do and, for the millionth time, is a good indicator for the majority. The links to support that are in CDC link I posted earlier. I'm on mobile and can't be bothered to get them


    Know were I can get my BF analysis done? About 5 hours away. And for a hefty price.
    Even when doing a health screening, how often would they be able to have the option of measuring BF?


    Amazon can bring a unit to your door that will give you a better body fat analysis than BMI for under $40.

  • 3dogsrunning
    3dogsrunning Posts: 27,167 Member
    One caveat about the thing with the belt, it can depend on how you wear your pants. The waist measurement for assessing body composition is supposed to be taken around the navel, whereas most men wear the 'waist' of their pants more toward the top of the hips. I wear size 36 pants, but my actual waist measurement is 47.5. Fortunately, my belly distension is not flabby, or I'd be sporting a major 'dunlap' aside from just being round.

    So basically what you are saying is- you are obese with an unhealthy amount of visceral fat and you have problems with your BMI.

    I'm saying I am obese and working on it, and BMI is completely irrelevant. Body Fat Percentage is a useful tool.

    Irrelevant except for the large percentage of people it is a good indicator for.

    How does one know if they're inside or outside the 'large percentage'? What is the 'large percentage'... the cumulative Normal at one standard deviation... two...? To me, this is what makes BMI a weak metric.

    I don't disagree that it's a good indicator for those near mean height, but it doesn't scale well once you start moving away from the center of the distribution because the formula ignores the square-cube law.

    (1)
    Are you in a category that you feel you do not fit? (2) If so, there are a number of other tools to use to evaluate if you are in the majority or one of the outliers.
    Having body fat measured it one.

    (1) I have no way of knowing - that's really the point.

    (2)
    In a world where better (more meaningful, more accurate, more reliable) metrics are available, why do we need BMI? It reminds me of the Pop Tart commercials where the Pop Tarts are next to some eggs, toast, and orange juice: Part of this complete breakfast! The BMI is the Pop Tart of the health metric world.

    My BMI is 26... am I overfat or overmuscular? Looking in the mirror will tell me more than "26" ever will.

    At the end of the day, it's just a number, so I'm not too concerned about it per se. But when a metric doesn't apply equally to ALL, but it's used to measure ALL (and especially when it factors into how much one pays for health insurance, etc.), then I start to have a problem with it.

    I don't disagree with your last point. But the thread was about judging a healthy weight. I still feel it's a decent place to start when trying to decide on a healthy weight.

    you said you have no idea about number one but then say looking in the mirror tells you more. So you do know.
  • bennettinfinity
    bennettinfinity Posts: 865 Member
    One caveat about the thing with the belt, it can depend on how you wear your pants. The waist measurement for assessing body composition is supposed to be taken around the navel, whereas most men wear the 'waist' of their pants more toward the top of the hips. I wear size 36 pants, but my actual waist measurement is 47.5. Fortunately, my belly distension is not flabby, or I'd be sporting a major 'dunlap' aside from just being round.

    So basically what you are saying is- you are obese with an unhealthy amount of visceral fat and you have problems with your BMI.

    I'm saying I am obese and working on it, and BMI is completely irrelevant. Body Fat Percentage is a useful tool.

    Irrelevant except for the large percentage of people it is a good indicator for.

    How does one know if they're inside or outside the 'large percentage'? What is the 'large percentage'... the cumulative Normal at one standard deviation... two...? To me, this is what makes BMI a weak metric.

    I don't disagree that it's a good indicator for those near mean height, but it doesn't scale well once you start moving away from the center of the distribution because the formula ignores the square-cube law.

    (1)
    Are you in a category that you feel you do not fit? (2) If so, there are a number of other tools to use to evaluate if you are in the majority or one of the outliers.
    Having body fat measured it one.

    (1) I have no way of knowing - that's really the point.

    (2)
    In a world where better (more meaningful, more accurate, more reliable) metrics are available, why do we need BMI? It reminds me of the Pop Tart commercials where the Pop Tarts are next to some eggs, toast, and orange juice: Part of this complete breakfast! The BMI is the Pop Tart of the health metric world.

    My BMI is 26... am I overfat or overmuscular? Looking in the mirror will tell me more than "26" ever will.

    At the end of the day, it's just a number, so I'm not too concerned about it per se. But when a metric doesn't apply equally to ALL, but it's used to measure ALL (and especially when it factors into how much one pays for health insurance, etc.), then I start to have a problem with it.

    I don't disagree with your last point. But the thread was about judging a healthy weight. I still feel it's a decent place to start when trying to decide on a healthy weight.

    you said you have no idea about number one but then say looking in the mirror tells you more. So you do know.

    Yep.... I know... BMI is clueless.
  • kimny72
    kimny72 Posts: 16,023 Member
    And I have always been told that bio-electrical impedance is at best only good to evaluate whether your BF% is trending up or down, not to get an accurate number.

    I am about an hour outside of NYC, and I would have to go into the city to get DXA or hydrostatic weighing. Not practical.
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
    kimny72 wrote: »
    According to his stats, Bolt is 6'5", 207 lbs.

    Right, he's a good normal size for his height, other than having much less fat than most.
    He is not even close to lean-looking IMHO. He is a solid chunk of impressive muscle.

    Lean means "not fat". You can be lean at a low muscle mass or at a very high muscle mass.

    The standard presented by the BMI charts promotes an "ideal" of normal to low body fat combined with low muscle mass. There is no health benefit to having less muscle. The average person would be healthier at a low-normal body fat with an amount of muscle that would push them to the top end of "healthy" or into "overweight" according to BMI. BMI is absolutely not an optimal health standard.
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
    kimny72 wrote: »
    And I have always been told that bio-electrical impedance is at best only good to evaluate whether your BF% is trending up or down, not to get an accurate number.

    This is true, and yet it's still more accurate than BMI.

    Or if you don't trust BIA there are a myriad of other formulas more accurate than BMI where you can take some measurements and type them into a web site. Height to waist ratio, and the formulas the military branches use when BMI fails and they "go to the tape" both come to mind.

  • bennettinfinity
    bennettinfinity Posts: 865 Member
    In a world where better (more meaningful, more accurate, more reliable) metrics are available, why do we need BMI?

    Since you can spend $1,000 on a bike wheel that measures your power output, why would anybody spend $50 on a heart rate monitor to guess at exertion levels?

    Because BMI can be measured almost for free and an accurate measure of body fat involves considerably more expense. This matters for some applications.

    Also, data quality matters. I have a bio-impedance scale, my %BF changes by a few points from one day to the next. So I have little confidence in my scale's ability to measure this. But my BMI is correct for me. I can tell by looking in the mirror that I'm not an outlier for BMI.

    BMI is good for most of the population, and that allows population level reporting, for people to spot trends. We're not going to give everybody on the planet a monthly DEXA scan to have statistics like which states or countries have more/less obesity.

    Have you ever heard the saying "don't let the perfect be the enemy of the good?"

    I don't recall mentioning bio-impedance or DEXA scans...

    I'm 6'2", 203 lbs... BMI=26; "Overweight". Am I over by fat or am I over by muscle? BMI doesn't know and it doesn't care, but it makes a difference.

    Am I healthy?

    You don't know - and neither does BMI.
  • MarkusDarwath
    MarkusDarwath Posts: 393 Member
    edited August 2016
    Because BMI can be measured almost for free and an accurate measure of body fat involves considerably more expense. This matters for some applications.

    As I just pointed out, there are other almost free methods of assessing body fat that are more accurate than BMI.

    BMI is good for most of the population, ...........and that allows population level reporting,............ for people to spot trends.

    I highlighted a very relevant point here. BMI was originally developed for populational studies, not for individual use. Using it to assess individual health is a misapplication of the formula.



  • MarkusDarwath
    MarkusDarwath Posts: 393 Member

    You keep saying that. It isn't meant to be right for everyone nor does anyone claim that.
    By going to a secondary measure they are using it exactly as it was meant to - as an indicator. And in that case it indicates someone *might* be overweight or in some cases of males, obese. Then they use other methods to determine if someone is, in fact, overweight. In some cases the follow up methods confirm the person is overweight. In others, that they are an outlier.

    Then why bother with it when there are other methods that are just as cheap and easy?

  • Packerjohn
    Packerjohn Posts: 4,855 Member
    Packerjohn wrote: »
    One caveat about the thing with the belt, it can depend on how you wear your pants. The waist measurement for assessing body composition is supposed to be taken around the navel, whereas most men wear the 'waist' of their pants more toward the top of the hips. I wear size 36 pants, but my actual waist measurement is 47.5. Fortunately, my belly distension is not flabby, or I'd be sporting a major 'dunlap' aside from just being round.

    Sorry, as has been mentioned before you are wearing size 36 pants because you have a large amount of visceral fat. The location of the fat forces your pants to fit that way. Most men don't wear a pants size 12 inches less than their waist size.

    I never claimed I didn't. I was merely pointing out that using your belt size as an indicator is not going to be accurate if your belly is larger than your belt. If I assessed myself based on my pants size, it would suggest I'm in pretty decent shape, which clearly is not the case.

    None of the measurements that use a ratio use belt size as a factor. They use waist measuremnt at the natural waist (you can Google and find where that is) vs height ot hips measurement.
  • CaraRahl
    CaraRahl Posts: 72 Member
    just my 2 cents worth here, I believe that while BMI can be a useful tool in determining a healthy weight, it is not the only tool that can be used. Personally, I track a variety of things to tell me how I'm doing, including my BMI, my waist to hip ratio, my waist to height ratio, and a rough estimate of my BF% (figured out from an average of 3 different online calculators and a set of calipers that I own) to figure out my healthy weight range. BMI in my opinion is a good starting point for those who aren't as familiar with different ways of measuring their progress.