7 ms·

Is BMI a good indicator of obesity, though?

purec 6y ago
It works for the average person but becomes distorted when you look at athletes, especially those that need to put on more muscle.
SketchySeaBeast 6y ago
I understand the objections to BMI comparisons at an individual level (though I believe people think themselves a bit too exceptional too often), but as part of a larger study, I would think it'd make a good additional data point, no?
- altvali 6y ago
  It most definitely would, but measuring body fat percentage would be better.
  - SketchySeaBeast 6y ago
    But then you couldn't easily extrapolate to the population. Well, you could, but you'd require the population to have an understanding of their body fat percentages. BMI isn't ideal, but it's quick and dirty, easy to collect and it should be relatively reliable for the population.
    - greenbush 6y ago
      It's not that straightforward as the BMI thresholds vary by ethnicity: https://www.hsph.harvard.edu/obesity-prevention-source/ethnic-differences-in-bmi-and-disease-risk/ https://www.hsph.harvard.edu/obesity-prevention-source/ethni...
graeme 6y ago
It’s actually pretty decent. It can make errors in the case of people with extreme muscle mass, or very low muscle mass for their size, or the very short, or the very tall. But for most people, if you’re over 25 bmi you probably could lose some weight. And at a population levels the errors above average out, even in a smaller group. People make a big deal over the exceptions to it while ignoring that it is broadly accurate and that exceptions are not as common.
- sunpar 6y ago
  At 6'1" BMI seems to say I should be between 140lbs and 185 lbs. I'm currently 165 lbs and feel pretty skinny -- I can't imagine being healthy at 140 lbs! The 185 seems about right -- I've been close to 180 lbs and felt like I could lose a few.
  - deleted 6y ago
    [deleted]
  - shajznnckfke 6y ago
    I guess people are downvoting because it’s not super relevant to the discussion, but I have a similar opinion that the BMI normal weight range is unreasonable for me. I’ve been in these two modes: 1) genuinely overweight with too much fat and not enough muscle 2) nearly overweight according to BMI while very fit, with low fat and high muscle. got here from the other state by exercising a lot, losing fat and gaining muscle. I think I would have to become totally sedentary again to get rid of my muscle mass and actually reach the lower end of “normal weight” according to BMI, while starving myself and feeling feeble.
    - Reelin 6y ago
      > nearly overweight according to BMI while very fit, with low fat and high muscle Not knowing you personally, it seems statistically more likely to me that your idea of "fit, low fat, high muscle" is what's at fault here (as opposed to BMI). Sure, you could be an exception. But all things being equal, you probably aren't. (Also maybe I misunderstand - if you mean that BMI was saying you were at the high end of normal then ... isn't that just saying that you're fine?) (Of course if a medical professional or academic specializing in such matters also thought BMI was inaccurate in your case then I would tend to view things differently.)
      - shajznnckfke 6y ago
        I can believe it. I’m curious what typical body types were like in the hunter/gather societies human evolved in, and whether those are ideal for longevity and quality of life in modern society.
greenbush 6y ago
The issue with BMI is that the thresholds vary by ethnicity: https://www.hsph.harvard.edu/obesity-prevention-source/ethnic-differences-in-bmi-and-disease-risk/ https://www.hsph.harvard.edu/obesity-prevention-source/ethni...
thelittleone 6y ago
I'm 6' and 84kg (185lbs), I recently had a full health checkup. I do cardio and calaesthebics 90 mins a day during weekdays. I'm lean, not bulky. The top finding of the report. Overweight, consider a healthier diet and more exercise.
- PhantomGremlin 6y ago
  What is your waist circumference? The data show that waist circumference is more reliable and more closely correlated with diseases associated with obesity. https://www.webmd.com/diet/features/how-accurate-body-mass-index-bmi https://www.webmd.com/diet/features/how-accurate-body-mass-i...
inspector-g 6y ago
It's actually not bad, but it's even better if you couple it with a simple waist circumference measurement (adjusted for sex, and for ethnic background in some circumstances).

It works for the average person but becomes distorted when you look at athletes, especially those that need to put on more muscle.

SketchySeaBeast 6y ago

I understand the objections to BMI comparisons at an individual level (though I believe people think themselves a bit too exceptional too often), but as part of a larger study, I would think it'd make a good additional data point, no?

altvali 6y ago
It most definitely would, but measuring body fat percentage would be better.
- SketchySeaBeast 6y ago
  But then you couldn't easily extrapolate to the population. Well, you could, but you'd require the population to have an understanding of their body fat percentages. BMI isn't ideal, but it's quick and dirty, easy to collect and it should be relatively reliable for the population.
  - greenbush 6y ago
    It's not that straightforward as the BMI thresholds vary by ethnicity: https://www.hsph.harvard.edu/obesity-prevention-source/ethnic-differences-in-bmi-and-disease-risk/ https://www.hsph.harvard.edu/obesity-prevention-source/ethni...

graeme 6y ago

It’s actually pretty decent. It can make errors in the case of people with extreme muscle mass, or very low muscle mass for their size, or the very short, or the very tall. But for most people, if you’re over 25 bmi you probably could lose some weight. And at a population levels the errors above average out, even in a smaller group. People make a big deal over the exceptions to it while ignoring that it is broadly accurate and that exceptions are not as common.

sunpar 6y ago
At 6'1" BMI seems to say I should be between 140lbs and 185 lbs. I'm currently 165 lbs and feel pretty skinny -- I can't imagine being healthy at 140 lbs! The 185 seems about right -- I've been close to 180 lbs and felt like I could lose a few.
- deleted 6y ago
  [deleted]
- shajznnckfke 6y ago
  I guess people are downvoting because it’s not super relevant to the discussion, but I have a similar opinion that the BMI normal weight range is unreasonable for me. I’ve been in these two modes: 1) genuinely overweight with too much fat and not enough muscle 2) nearly overweight according to BMI while very fit, with low fat and high muscle. got here from the other state by exercising a lot, losing fat and gaining muscle. I think I would have to become totally sedentary again to get rid of my muscle mass and actually reach the lower end of “normal weight” according to BMI, while starving myself and feeling feeble.
  - Reelin 6y ago
    > nearly overweight according to BMI while very fit, with low fat and high muscle Not knowing you personally, it seems statistically more likely to me that your idea of "fit, low fat, high muscle" is what's at fault here (as opposed to BMI). Sure, you could be an exception. But all things being equal, you probably aren't. (Also maybe I misunderstand - if you mean that BMI was saying you were at the high end of normal then ... isn't that just saying that you're fine?) (Of course if a medical professional or academic specializing in such matters also thought BMI was inaccurate in your case then I would tend to view things differently.)
    - shajznnckfke 6y ago
      I can believe it. I’m curious what typical body types were like in the hunter/gather societies human evolved in, and whether those are ideal for longevity and quality of life in modern society.

greenbush 6y ago

The issue with BMI is that the thresholds vary by ethnicity: https://www.hsph.harvard.edu/obesity-prevention-source/ethnic-differences-in-bmi-and-disease-risk/ https://www.hsph.harvard.edu/obesity-prevention-source/ethni...

thelittleone 6y ago

I'm 6' and 84kg (185lbs), I recently had a full health checkup. I do cardio and calaesthebics 90 mins a day during weekdays. I'm lean, not bulky. The top finding of the report. Overweight, consider a healthier diet and more exercise.

PhantomGremlin 6y ago
What is your waist circumference? The data show that waist circumference is more reliable and more closely correlated with diseases associated with obesity. https://www.webmd.com/diet/features/how-accurate-body-mass-index-bmi https://www.webmd.com/diet/features/how-accurate-body-mass-i...

inspector-g 6y ago

It's actually not bad, but it's even better if you couple it with a simple waist circumference measurement (adjusted for sex, and for ethnic background in some circumstances).