New BMI formula. Good news for some..

mfs1011
mfs1011 Posts: 8 Member
in Fitness and Exercise
Oxford Mathematician Prof Nick Trefethen has designed a new formula to calculate BMI that he claims is more accurate.

From the Oxford U Press release: "Body Mass Index (BMI) is derived from a simple mathematical formula, devised by Belgian scientist Adolphe Quetelet in the 1830s, that divides a person's weight in kilograms by their height in metres squared to arrive at an estimate of an individual's body fat.

It's supposed to provide an approximate measure to help judge if someone has a healthy weight – and indicate, for instance, if they are obese. But as Nick Trefethen of Oxford University's Mathematical Institute pointed out in a recent letter to The Economist the basic formula BMI relies on is flawed:

'If all three dimensions of a human being scaled equally as they grew, then a formula of the form weight/height3 would be appropriate. They don't! However, weight/height2 is not realistic either,' Nick tells me.

'A better approximation to a complex reality, which is the reform I wish could be adopted, would be weight/height2.5. Certainly if you plot typical weights of people against their heights, the result comes out closer to height2.5 than height2.'

Sticking with the current formula, he says, leads to confusion and misinformation: 'Because of that height2 term, the BMI divides the weight by too large a number for short people and too small a number for tall people. So short people are misled into thinking they are thinner than they are, and tall people are misled into thinking they are fatter than they are.'"

Read the rest of the article here:
http://www.ox.ac.uk/media/science_blog/130116.html

And an associated Oxford U post here:
http://people.maths.ox.ac.uk/trefethen/bmi.html

You can calculate your new and more accurate BMI here:
http://people.maths.ox.ac.uk/trefethen/bmi_calc.html

Being taller but close to my goal weight, my BMI went down making me 'healthy' rather than 'overweight'.

Whether this new method of calculating BMI goes on to become generally adopted by the World Health Organisation and science in general, its too early to say. But it may be worth reviewing your weight goals?
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Replies

  • Arismar2022
    Arismar2022 Posts: 24 Member
    Interesting! Thank you for sharing!
  • katevarner
    katevarner Posts: 884 Member
    Wow, thanks for sharing this! I'm short and always thought the old formula was a little off for me. This makes my range much more realistic, too.
  • alexbusnello
    alexbusnello Posts: 1,010 Member
    Thank you :smile:
  • LeslieN65
    LeslieN65 Posts: 127 Member
    Cool! Thanks~
  • krystina_letitia9
    krystina_letitia9 Posts: 697 Member
    My BMI went up. This formula sucks! :laugh:
  • alasin1derland
    alasin1derland Posts: 575 Member
    I am 5'7" and it was less than one different for BMI, and as far as pounds go it upped my high range by half a pound. I must be the right height for both formulas. My husband is taller, I will check his next.
  • SadieToughLady
    SadieToughLady Posts: 44
    I don't like BMI at all because it doesn't take into account muscle mass. I have a lot of muscle on my body. I always weigh more than I look and it is because of the muscle. I still have about 10 pounds to lose, but overall, I am not obese like the BMI calculators tell me I am.
  • OtekahSunshield
    OtekahSunshield Posts: 42 Member
    My BMI went up. T_T

    Still interesting though.
  • kr1stadee
    kr1stadee Posts: 1,774 Member
    The new formula put my number up one, and my ideal weight range went from 102-141 to 103-140.. no real change for me.
  • pet1127
    pet1127 Posts: 572 Member
    bump
  • dave4d
    dave4d Posts: 1,155 Member
    It still classifies me as overweight. I did a reading with my calipers last night, they put me at 11% bodyfat. I'd have to lose a lot of muscle to get down to a healthy weight according to either BMI scale.
  • goldfinger88
    goldfinger88 Posts: 686 Member
    Mine went from healthy to overweight. Think I'll stick with the old one. :) Actually, BMI is not at all a good indicator of fitness and the number you get is not body fat. Indeed, body fat is the best way to gauge your fitness, using your waist measurement as the gold standard. BMI has proven to be totally unreliable. I doubt the "new" process is an improvement.
  • Emma_Problema
    Emma_Problema Posts: 422 Member
    Heh. Works for me. From "overweight" to "healthy". But I was always knew that BMI was bull. I've kind of questioned it ever since learning that they changed the "healthy" cutoffs from 27 for women and 28 for men, to 25 for both.

    Thanks for sharing! It's an interesting article!
  • SuffolkSally
    SuffolkSally Posts: 964 Member
    It drops my BMI from 24.4 to 23.4 (I'm 6'). Both are healthy range though. Just need to adjust the fat/muscle balance now!
  • Tara1B
    Tara1B Posts: 78
    I'm 5ft and my BMI went up from 19.88 to 20.94 gawd dammit!
  • squirrelythegreat
    squirrelythegreat Posts: 158 Member
    110-145 range huh... Gdiaf.
  • diodelcibo
    diodelcibo Posts: 2,564 Member
    My standard BMI is 29.30 and my new is BMI 27.25.
  • IronSmasher
    IronSmasher Posts: 3,908 Member
    It's still just as broken. What a waste of time.
  • hazelovesfood
    hazelovesfood Posts: 454 Member
    Sorry but this is bull, ive just worked mine out and it says im obese, yeah i clearly look it dont i.:mad:
  • oohmercyme
    oohmercyme Posts: 279 Member
    My goal weight is 140 (because I am very muscular) and old BMI says 130 is the highest "healthy" weight for me. New BMI says 137, which is more realistic, but reality, 140 would would NOT be overweight for me. (I'm in the BMI is BS camp also).
  • Mom_To_5
    Mom_To_5 Posts: 646 Member
    Mine went up as well.
  • ILiftHeavyAcrylics
    ILiftHeavyAcrylics Posts: 27,732 Member
    Sorry but this is bull, ive just worked mine out and it says im obese, yeah i clearly look it dont i.:mad:

    Did you switch it from kgs/cms to pounds/inches? I thought I had it right but then it said I was obese so I looked at it again and it was set on kgs/cms.


    For me it's really close to the same.
  • SherryTeach
    SherryTeach Posts: 2,836 Member
    Under the new formula, I would still be a healthy weight if I weighed 93 pounds. I think I'd be in the hospital.
  • hazelovesfood
    hazelovesfood Posts: 454 Member
    It still classifies me as overweight. I did a reading with my calipers last night, they put me at 11% bodyfat. I'd have to lose a lot of muscle to get down to a healthy weight according to either BMI scale.
    If that is you in your picks, you are clearly not overweight, omg this crap annoys me, what do they expect people to be, stick thin!!!!!!!!!!!!
  • IronSmasher
    IronSmasher Posts: 3,908 Member
    I'm impressed by the amount of people that know how to work out using x^2.5
  • Roni_M
    Roni_M Posts: 717 Member
    I'm 5'10" and it added about 5lbs to either end of the "healthy range". I personally think BMI is accurate for the masses (exceptions would be body builders, etc.). But being tall gives me a 50lbs range of "healthy" weights, which to me allows for various builds and muscle mass. I might feel differently about it if I was short and had a much smaller "healthy" window to fit into.
  • hazelovesfood
    hazelovesfood Posts: 454 Member
    Sorry but this is bull, ive just worked mine out and it says im obese, yeah i clearly look it dont i.:mad:

    Did you switch it from kgs/cms to pounds/inches? I thought I had it right but then it said I was obese so I looked at it again and it was set on kgs/cms.


    For me it's really close to the same.
    i worked it both ways,im 5 9 and it says in obese, I know what obese looks like, and im not it, no offense to anyone.
  • hazelovesfood
    hazelovesfood Posts: 454 Member
    Sorry but this is bull, ive just worked mine out and it says im obese, yeah i clearly look it dont i.:mad:

    Did you switch it from kgs/cms to pounds/inches? I thought I had it right but then it said I was obese so I looked at it again and it was set on kgs/cms.


    For me it's really close to the same.
    i worked it both ways,im 5 9 and it says in obese, I know what obese looks like, and im not it, no offense to anyone.
    [/quote
    actually dont it again,and i had put in 175 kg, not llbs. but still says in overweight.
  • umachanxo
    umachanxo Posts: 926 Member
    I am 5'7" and it was less than one different for BMI, and as far as pounds go it upped my high range by half a pound. I must be the right height for both formulas. My husband is taller, I will check his next.

    Same. I'm 5"7 also, and it's pretty well the same.
  • askeates
    askeates Posts: 1,490 Member
    Wow, that makes my goal vs the BMI goal for me more realistic... it tells me I should be at 128, last time I was that small I was told by my Dr that I was unhealthy! I'm shooting for 155-160 (when I think I looked the best).... that is a pretty big difference!

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