The BMI and taller people...

  • Posted by a hidden member.
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    Oct 23, 2007 12:06 AM GMT
    Forgive me if this has been discussed before, but I'd like to get some y'alls thoughts on the BMI. I have read before that the BMI formula is inherently flawed but works just fine for those of average height. However when you get above 6 feet tall (me, and seemingly a lot of people on here), it starts to become less accurate.

    Glenn Murray is a professor at the Colorado School of Mines, and he has another formula... he describes his formula here (you can enter your height and weight, and it will calculate it using the CDC's method and his):

    http://www.mines.edu/~gmurray/BMIApplet/BMIApplet.html

    According to this, someone who is 6'3" and 200lbs, would be "normal weight" according to one, and "overweight" according to the other...

    The guy's got a PHD in Algebraic Geometry, and a Bachelor's in Physics and Math... seems like he'd know what he's talking about, right?

    How do you guys view the BMI as a measure of fitness anyway? Is it just a number (like weight) that people should know but not really care about all that much as long as their exercising and eating correctly?
  • MSUBioNerd

    Posts: 1813

    Oct 23, 2007 1:54 AM GMT
    The BMI as it's marketed is merely a stand in for the old height/weight charts. It doesn't take into account quite a number of factors: relative muscle mass versus fat deposits, distribution of muscle and fat across the body, differences in bone structure, etc. In one of my biology labs we did a much more detailed analysis, which involved a huge number of measurements (off the top of my head, I remember that we measured distance between shoulder blades, length of the forearm, length of the femur, circumference of the wrist, narrowest part of the waist, circumference at the navel, widest circumference of hip/rear, several points of the leg, heart rate and blood pressure after several different degrees of physical exercise and after certain amounts of recovery time...), and plugged them all into a large formula to get something also called a BMI, but which seemed to correlate very well with general health and fitness of the people measured.

    Bottom line, it's a number worth knowing, but it's not really a litmus test for anything in particular. General activity level and diet matter a lot more.
  • OutOfEden

    Posts: 100

    Oct 23, 2007 2:27 AM GMT
    It's why I list myself as "Overweight". There is no chance I could ever reach non-overweight status on the official BMI for my height of 6'4" without losing all of my fat AND muscle mass and considerable bone density. I did the math one day in Biology. I'll check out this link and see what the prof. thinks of me icon_biggrin.gif

  • Salubrious

    Posts: 420

    Oct 23, 2007 2:41 AM GMT
    I think it said I had to be about 165 to be normal weight or something crazy like that.
  • Posted by a hidden member.
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    Oct 23, 2007 12:31 PM GMT
    BMI = BUNK
  • DiverScience

    Posts: 1426

    Oct 23, 2007 12:48 PM GMT
    BMI is *garbage*

    If you have muscle, you're "overweight."

    If you have thicker bones, you're "overweight."

    If you're a woman with larger hip bones, you're "overweight."

    If you're tall, you're "overweight."



    Hell, *I'M* barely not "moderately obese" (3 pounds right now) by that measurement. It is utterly useless.
  • Posted by a hidden member.
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    Oct 25, 2007 5:49 AM GMT
    Me too. My BMI says I'm borderline overweight, but my mirror tells me otherwise.

    I trust the mirror more than any BMI nonsense.
  • Posted by a hidden member.
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    Oct 25, 2007 6:27 AM GMT
    According to the BMI I'm overweight. I'm average height (5ft9). It must be my humongously huge willy.
  • Posted by a hidden member.
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    Aug 07, 2009 5:32 AM GMT
    http://www.npr.org/templates/story/story.php?storyId=106268439&sc=fb&cc=fp
  • swimbikerun

    Posts: 2835

    Aug 07, 2009 5:42 AM GMT
    MSUBioNerd saidThe BMI as it's marketed is merely a stand in for the old height/weight charts. It doesn't take into account quite a number of factors: relative muscle mass versus fat deposits, distribution of muscle and fat across the body, differences in bone structure, etc. In one of my biology labs we did a much more detailed analysis, which involved a huge number of measurements (off the top of my head, I remember that we measured distance between shoulder blades, length of the forearm, length of the femur, circumference of the wrist, narrowest part of the waist, circumference at the navel, widest circumference of hip/rear, several points of the leg, heart rate and blood pressure after several different degrees of physical exercise and after certain amounts of recovery time...), and plugged them all into a large formula to get something also called a BMI, but which seemed to correlate very well with general health and fitness of the people measured.

    Bottom line, it's a number worth knowing, but it's not really a litmus test for anything in particular. General activity level and diet matter a lot more.
    But the BMI places you on the lean end of the scale. I'd say, overall it is rather accurate. From your pic, I would say you are nice and lean.

    It has a better successor in the
    Fat Free Mass Index (FFMI)

    In fact, using the tools in conjunction, it's easier to understand your Lean Body Mass (BMI). That is what one weighs, muscles and bones.
    The problem really comes down to: how much body fat do you have?

    Here's a third tool
    Understanding Your Fat Percentage

    You can see that men could have a body fat percentage all the way up 25% and still be considered 'acceptable' or not 'obese'.

    The most accurate method for determining body fat percentage is the hydrostatic method. It is expensive and I would only recommend it for people who are training to be professional athletes or people who have nothing better to do with the time and money.

    What is most important rewlor is that you are eating healthy, fresh food, getting exercise and plenty to rest. Interesting how those might be considered as luxuries these days, eh?

    But, if you want to reduce your body fat percentage you do need nothing other than reduce your caloric intake, keep working out, eating well and getting plenty of rest.

    Yes, it does simply come down to numbers.

    Athletic Male Body Research

    Go around this site, find guys who have a body you might like, if you want to change your body type. Put in their reported height and weight, maybe guess their body fat percentage. See what you think the tools are reporting.

    I'm: 6'2", currently around 183 pounds with an approximate body fat percentage of 16% and a plan on losing even more body fat.

    I can see a plan on bouncing between 10 and 17 per cent body fat over the course of a year, depending on training goals.
  • Posted by a hidden member.
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    Aug 07, 2009 5:49 AM GMT
    I think BMI is total B.S. 5'11" tall and 230lbs it says I am obese.


    Do I weigh more than I should? Probably (20-25lbs).


    Am I obese? No way!


    If you have a fair amount muscle the BMI is so far off it is laughable.