6 ms·

BMI is the least worst. Tons of methods have been tried and they are all worse. We need cheap, fast and easy. Thats what BMI is. To get more accurate you need s

BMI is the least worst. Tons of methods have been tried and they are all worse. We need cheap, fast and easy. Thats what BMI is. To get more accurate you need specialized equipment and or some math knowledge. Better = costs more. Thats why we have BMI and why people complain endlessly about it.

RC_ITR 3y ago
But it could be a more complex formula. For example, the max 'healthy' weight for a 6'10" person is 230lbs. That's more or less Kevin Durant's draft stats and he looked like this: https://twitter.com/si_vault/status/749993324195479553 https://twitter.com/si_vault/status/749993324195479553
- confidantlake 3y ago
  For sure, but most people are not 6'10. For 95%+ of the population it works fine.
  - RC_ITR 3y ago
    Just to be clear, the formula for BMI is 'weight (lb) / [height (in)]^2 x 703' and all the talk of "it's the cheapest and easiest way" ignores the fact that we could add other cheap measurements (like hip and shoulder circumference, or Age) or we could reexamine the formula without adding new variables to make it better.
  - klooney 3y ago
    You're too generous, that's over the 99th percentile. 95th is 6'2"- https://www.cdc.gov/growthcharts/data/set2/chart-07.pdf https://www.cdc.gov/growthcharts/data/set2/chart-07.pdf It's fine if BMI breaks down at the 99.99th percentile, doctors can use their eyes.
- orangepurple 3y ago
  Differences in body proportion, fat-free body density, and hydration may have a larger effect on the validity of body-composition devices in minority populations than previously assumed. Based on the review of literature, DXA is a valid method in a multi-ethnic sample, if individuals are Caucasian/White and African American/Black. However, there is insufficient evidence to recommend use in Hispanic/Latinx and Asian adults, Native American males, or African-American/Black females. ADP is valid for Hispanic and African-American/Black males when utilizing race-specific equations; however, results are inconclusive in other racial/ethnic groups and sexes. For BIA, body-composition estimates may be valid in a multi-ethnic sample, but the literature demonstrates disparate results between races/ethnicities. BIA may provide valid results in Hispanic and Native American populations, as well as Asian populations utilizing race-specific equations. However, BIA is still not recommended for African-American/Black individuals based on current data. The lack of validation using a multi-compartment model criterion limits the certainty of conclusions, particularly regarding the validity of ADP and BIA. Glossary: ADP: air displacement plethysmography BIA: bioelectrical impedance devices / bioelectrical impedance analysis Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8528114/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8528114/
- Gwypaas 3y ago
  Arnold Schwarzenegger hade an obese BMI in competition trim. Outliers does not invalidate a generic measure, they are outliers. https://upload.wikimedia.org/wikipedia/commons/0/05/Arnold_Schwarzenegger_1974.jpg https://upload.wikimedia.org/wikipedia/commons/0/05/Arnold_S...
  - goosinmouse 3y ago
    The argument of "BMI doesnt account for muscles/height" always sucks because of what you said, they're just outliers. Realistically nobody that is TRULY an outlier takes BMI into account in anyway.
- orangepurple 3y ago
  If you are white use this formula to calculate body fat percentage with a standard error of the estimate (SEE) of 4.74%: We studied a sample of 6,510 white subjects (2,154 men, 4,356 women), aged 18–80 years, including patients visiting our department. The study was performed to valuate the usefulness of a new equation: BF% = –44.988 + (0.503 x age) + (10.689 x sex) + (3.172 x BMI) – (0.026 x BMI^2) + (0.181 x BMI x sex) – (0.02 x BMI x age) – (0.005 x BMI^2 x sex) + (0.00021 x BMI^2 x age) where male = 0 and female = 1 for sex, and age in years, developed by multiple regression to predict BF% This online calculator claims to use this algorithm: https://www.omnicalculator.com/health/body-fat https://www.omnicalculator.com/health/body-fat Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263863/pdf/383.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263863/pdf/383...
nradov 3y ago
Waist to hip ratio is the least worst. It's just as cheap, fast, and easy. And it's a more accurate predictor of mortality. https://www.medscape.com/viewarticle/981431 https://www.medscape.com/viewarticle/981431
- tomjakubowski 3y ago
  this makes sense - carrying excess abdominal fat is a sign of poor metabolic health. and taking a ratio of circumferences instead of weight/height accounts for muscle being denser than fat
- swatcoder 3y ago
  It's almost impossible for people to consistently measure, which throws self-assessment out the window, and remains a challenge in clinical settings. Pot belly guy measures his waist at his ribs, pear shaped lady rests the tape above her saddle bags, tape isn't level this time, tape is slack that time, etc etc It might only require tape and might have useful health correlates given good values, but getting those good values is just not something epidemiologists or even clinicians can rely on in the field.
wil421 3y ago
Exactly, BMI is an OK gauge for general use. When I was younger and in shape bulked up with single digit body fat it was not useful. I was obese/overweight in BMI only. Now that I am more sedentary due to office job and less time because I have kids it’s a useful gauge to help find my ideal weight.
- jerrycruncher 3y ago
  And the people who are more muscular _know_ that BMI isn't going to be accurate for them. The complaints seem to be somewhat bad faith arguments from the population for whom it is accurate, but wishes it weren't.
  - goosinmouse 3y ago
    This pretty much nails it. Im fit and on the muscular side, i'd say im pretty ok for a natural and i've always rode on the line of overweight on the BMI scale. But i never really cared, and nobody that is a bodybuilder cares either. Like you said, the complaints are always from the population for whom it is accurate. They're usually in denial and typically vastly overestimate how much muscle they're actually carrying underneath their visible layers of fat. Check the reddit/bulkorcut subreddit for some examples. If i had to spitball, i'd say only 20-30% of people that post their actually have a good idea of where they are in terms of BMI and body fat. There is an alarming amount of people that i'd consider their physique in the top 1% to top .1% in the world that believe they are fat. And there is an extremely alarming amount of people who are likely 25%+ and even sometimes 30%+ body fat that think they're in a healthy BMI range and ask if they should bulk. TL:DR - BMI is more accurate than not for people who need the scale. And if anything, it underestimates obesity for people who may not weight enough to be overweight, but still sit at 30%+ body fat.
    - iwonthecase 3y ago
      > people who are likely 25%+ and even sometimes 30%+ body fat that think they're in a healthy BMI range a Something I've observed is that people don't perceive weight on an absolute scale, but relative to other people. Really skews things depending on their local obesity rates.
chrisfosterelli 3y ago
Yeah I've always felt that it's unrealistic to expect a single number to effectively represent a person's health. Of course it's useful and of course there's caveats and of course a proper health evaluation should have a more holistic view than just BMI.
- bagels 3y ago
  I thought it was meant more to assess how fat someone is, not health?
  - chrisfosterelli 3y ago
    What's the point of discussing how fat someone is within a medical context if not for evaluation of their health? It's fairly implied you aren't using BMI to check for MS.

RC_ITR 3y ago

But it could be a more complex formula. For example, the max 'healthy' weight for a 6'10" person is 230lbs. That's more or less Kevin Durant's draft stats and he looked like this: https://twitter.com/si_vault/status/749993324195479553 https://twitter.com/si_vault/status/749993324195479553

confidantlake 3y ago
For sure, but most people are not 6'10. For 95%+ of the population it works fine.
- RC_ITR 3y ago
  Just to be clear, the formula for BMI is 'weight (lb) / [height (in)]^2 x 703' and all the talk of "it's the cheapest and easiest way" ignores the fact that we could add other cheap measurements (like hip and shoulder circumference, or Age) or we could reexamine the formula without adding new variables to make it better.
- klooney 3y ago
  You're too generous, that's over the 99th percentile. 95th is 6'2"- https://www.cdc.gov/growthcharts/data/set2/chart-07.pdf https://www.cdc.gov/growthcharts/data/set2/chart-07.pdf It's fine if BMI breaks down at the 99.99th percentile, doctors can use their eyes.
orangepurple 3y ago
Differences in body proportion, fat-free body density, and hydration may have a larger effect on the validity of body-composition devices in minority populations than previously assumed. Based on the review of literature, DXA is a valid method in a multi-ethnic sample, if individuals are Caucasian/White and African American/Black. However, there is insufficient evidence to recommend use in Hispanic/Latinx and Asian adults, Native American males, or African-American/Black females. ADP is valid for Hispanic and African-American/Black males when utilizing race-specific equations; however, results are inconclusive in other racial/ethnic groups and sexes. For BIA, body-composition estimates may be valid in a multi-ethnic sample, but the literature demonstrates disparate results between races/ethnicities. BIA may provide valid results in Hispanic and Native American populations, as well as Asian populations utilizing race-specific equations. However, BIA is still not recommended for African-American/Black individuals based on current data. The lack of validation using a multi-compartment model criterion limits the certainty of conclusions, particularly regarding the validity of ADP and BIA. Glossary: ADP: air displacement plethysmography BIA: bioelectrical impedance devices / bioelectrical impedance analysis Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8528114/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8528114/
Gwypaas 3y ago
Arnold Schwarzenegger hade an obese BMI in competition trim. Outliers does not invalidate a generic measure, they are outliers. https://upload.wikimedia.org/wikipedia/commons/0/05/Arnold_Schwarzenegger_1974.jpg https://upload.wikimedia.org/wikipedia/commons/0/05/Arnold_S...
- goosinmouse 3y ago
  The argument of "BMI doesnt account for muscles/height" always sucks because of what you said, they're just outliers. Realistically nobody that is TRULY an outlier takes BMI into account in anyway.
orangepurple 3y ago
If you are white use this formula to calculate body fat percentage with a standard error of the estimate (SEE) of 4.74%: We studied a sample of 6,510 white subjects (2,154 men, 4,356 women), aged 18–80 years, including patients visiting our department. The study was performed to valuate the usefulness of a new equation: BF% = –44.988 + (0.503 x age) + (10.689 x sex) + (3.172 x BMI) – (0.026 x BMI^2) + (0.181 x BMI x sex) – (0.02 x BMI x age) – (0.005 x BMI^2 x sex) + (0.00021 x BMI^2 x age) where male = 0 and female = 1 for sex, and age in years, developed by multiple regression to predict BF% This online calculator claims to use this algorithm: https://www.omnicalculator.com/health/body-fat https://www.omnicalculator.com/health/body-fat Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263863/pdf/383.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263863/pdf/383...

nradov 3y ago

Waist to hip ratio is the least worst. It's just as cheap, fast, and easy. And it's a more accurate predictor of mortality. https://www.medscape.com/viewarticle/981431 https://www.medscape.com/viewarticle/981431

tomjakubowski 3y ago
this makes sense - carrying excess abdominal fat is a sign of poor metabolic health. and taking a ratio of circumferences instead of weight/height accounts for muscle being denser than fat
swatcoder 3y ago
It's almost impossible for people to consistently measure, which throws self-assessment out the window, and remains a challenge in clinical settings. Pot belly guy measures his waist at his ribs, pear shaped lady rests the tape above her saddle bags, tape isn't level this time, tape is slack that time, etc etc It might only require tape and might have useful health correlates given good values, but getting those good values is just not something epidemiologists or even clinicians can rely on in the field.

wil421 3y ago

Exactly, BMI is an OK gauge for general use. When I was younger and in shape bulked up with single digit body fat it was not useful. I was obese/overweight in BMI only. Now that I am more sedentary due to office job and less time because I have kids it’s a useful gauge to help find my ideal weight.

jerrycruncher 3y ago
And the people who are more muscular _know_ that BMI isn't going to be accurate for them. The complaints seem to be somewhat bad faith arguments from the population for whom it is accurate, but wishes it weren't.
- goosinmouse 3y ago
  This pretty much nails it. Im fit and on the muscular side, i'd say im pretty ok for a natural and i've always rode on the line of overweight on the BMI scale. But i never really cared, and nobody that is a bodybuilder cares either. Like you said, the complaints are always from the population for whom it is accurate. They're usually in denial and typically vastly overestimate how much muscle they're actually carrying underneath their visible layers of fat. Check the reddit/bulkorcut subreddit for some examples. If i had to spitball, i'd say only 20-30% of people that post their actually have a good idea of where they are in terms of BMI and body fat. There is an alarming amount of people that i'd consider their physique in the top 1% to top .1% in the world that believe they are fat. And there is an extremely alarming amount of people who are likely 25%+ and even sometimes 30%+ body fat that think they're in a healthy BMI range and ask if they should bulk. TL:DR - BMI is more accurate than not for people who need the scale. And if anything, it underestimates obesity for people who may not weight enough to be overweight, but still sit at 30%+ body fat.
  - iwonthecase 3y ago
    > people who are likely 25%+ and even sometimes 30%+ body fat that think they're in a healthy BMI range a Something I've observed is that people don't perceive weight on an absolute scale, but relative to other people. Really skews things depending on their local obesity rates.

chrisfosterelli 3y ago

Yeah I've always felt that it's unrealistic to expect a single number to effectively represent a person's health. Of course it's useful and of course there's caveats and of course a proper health evaluation should have a more holistic view than just BMI.

bagels 3y ago
I thought it was meant more to assess how fat someone is, not health?
- chrisfosterelli 3y ago
  What's the point of discussing how fat someone is within a medical context if not for evaluation of their health? It's fairly implied you aren't using BMI to check for MS.