4 ms·

I wonder why they're using body fat percentage instead of BMI. While the two are strongly correlated [1], BMI seems more gender neutral. [1] https://bmcpublich

by tromp 4y ago

I wonder why they're using body fat percentage instead of BMI. While the two are strongly correlated [1], BMI seems more gender neutral. [1] https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-13-797/figures/1 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1...

johncessna 4y ago
BMI among fit individuals and athletes, is a terrible indicator of overall health. There's no distinction between a 250lb 6' man whose weight is predominately muscle vs a 250lb 6' man whose weight is predominately fat.
xwkd 4y ago
Having a high BMI and a low body fat percentage means that you are likely composed of a lot of muscle weight. I would think that this would correlate highly with physical strength, which I would also think is something we would want for our fighting forces.
- nordsieck 4y ago
  > Having a high BMI and a low body fat percentage means that you are likely composed of a lot of muscle weight. I would think that this would correlate highly with physical strength, which I would also think is something we would want for our fighting forces. It's complicated. I'm sure that military members are, on average, more muscular than civilians. But they're not typically very jacked compared to body builders or powerlifters. Moderate strength with high endurance (e.g. crossfit) is much more useful in combat than high strength but low endurance (e.g. powerlifting). And moderate strength with high endurance doesn't typically result in huge muscles. Having spent some time in the military, this generally aligns with my observations. Sure - there's some people who are jacked. But most people - even really elite guys - look pretty unassuming.
skerit 4y ago
BMI doesn't distinguish between weight by fat or weight by muscle mass. Someone with a lot of muscles and not a lot of fat can still have a high BMI
- mjbeswick 4y ago
  I have a BMI of 35 (obese) but have been weight training for 20 years and have a low body fat percentage. It works as a rough guide as it is easer to calculate than body fat percentage. Most people that go to the gym don't have much muscle; so unless someone is a dedicated bodybuilder or powerlifter it's good enough. You can tell just by looking at someone if they have large amounts of body fat!
QuercusMax 4y ago
Because BMI doesn't distinguish between Arnold Schwarzenegger and The Whale. If you're overweight for your height, even if it's solid muscle, it's all the same to BMI. Different body fat percentages for men and women is likely how they already do it.
- xedrac 4y ago
  When I was 8% body fat, my BMI was 24.8. That's when I realized that BMI, like most office chairs, is tailored for the average population.
- notfromhere 4y ago
  It works fine for the general population. We don’t exactly have an epidemic of bodybuilders
  - QuercusMax 4y ago
    But it's the military, so you're going to have a lot more super muscly and jacked guys than the general population. And it doesn't work well for the general population, anyway; it's a bad metric across the board. If you're very tall or very short, it misrepresents you. There are equally simple measures like waist-to-height ratio that have fewer issues. See this article: https://www.medicalnewstoday.com/articles/265215#Waist-to-height-ratio-better-than-BMI https://www.medicalnewstoday.com/articles/265215#Waist-to-he...
return_to_monke 4y ago
I do not find that BMI would be a good indicator, since (based on my own experience), people in the military are pretty muscular. BMI works for the average person but cannot differentiate between extra muscle mass and extra fat mass. on the topic of diversity, BMI often cannot be compared between ethnic/race groups: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4968570/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4968570/
bennettnate5 4y ago
They measure completely different things. BMI is a pure weight to height ratio--someone could have almost no skeletal muscle and have a "better" BMI than someone who works out daily and has heavy muscle density. They're strongly correlated in the statistical sense, but there's still a wide spread of body fat percentage for a given BMI. My guess is that they use different BMI metrics for men vs women when guaging fitness--that's how they keep things gender fair.
suslik 4y ago
BMI wouldn't be a good measure for this. The correlation might be strong, but very fit or muscular people (for instance, weight lifters, fighters etc) can have rather high BMI - and you really don't want to filter those out. Waist-hip ratio might be a good alternative measure.
arpinum 4y ago
If you look muscular and your BMI is too high, the military sends you to get measured with body calibers. BMI is just used for initial screening.

by tromp 4y ago

johncessna 4y ago

BMI among fit individuals and athletes, is a terrible indicator of overall health. There's no distinction between a 250lb 6' man whose weight is predominately muscle vs a 250lb 6' man whose weight is predominately fat.

xwkd 4y ago

Having a high BMI and a low body fat percentage means that you are likely composed of a lot of muscle weight. I would think that this would correlate highly with physical strength, which I would also think is something we would want for our fighting forces.

nordsieck 4y ago
> Having a high BMI and a low body fat percentage means that you are likely composed of a lot of muscle weight. I would think that this would correlate highly with physical strength, which I would also think is something we would want for our fighting forces. It's complicated. I'm sure that military members are, on average, more muscular than civilians. But they're not typically very jacked compared to body builders or powerlifters. Moderate strength with high endurance (e.g. crossfit) is much more useful in combat than high strength but low endurance (e.g. powerlifting). And moderate strength with high endurance doesn't typically result in huge muscles. Having spent some time in the military, this generally aligns with my observations. Sure - there's some people who are jacked. But most people - even really elite guys - look pretty unassuming.

skerit 4y ago

BMI doesn't distinguish between weight by fat or weight by muscle mass. Someone with a lot of muscles and not a lot of fat can still have a high BMI

mjbeswick 4y ago
I have a BMI of 35 (obese) but have been weight training for 20 years and have a low body fat percentage. It works as a rough guide as it is easer to calculate than body fat percentage. Most people that go to the gym don't have much muscle; so unless someone is a dedicated bodybuilder or powerlifter it's good enough. You can tell just by looking at someone if they have large amounts of body fat!

QuercusMax 4y ago

Because BMI doesn't distinguish between Arnold Schwarzenegger and The Whale. If you're overweight for your height, even if it's solid muscle, it's all the same to BMI. Different body fat percentages for men and women is likely how they already do it.

xedrac 4y ago
When I was 8% body fat, my BMI was 24.8. That's when I realized that BMI, like most office chairs, is tailored for the average population.
notfromhere 4y ago
It works fine for the general population. We don’t exactly have an epidemic of bodybuilders
- QuercusMax 4y ago
  But it's the military, so you're going to have a lot more super muscly and jacked guys than the general population. And it doesn't work well for the general population, anyway; it's a bad metric across the board. If you're very tall or very short, it misrepresents you. There are equally simple measures like waist-to-height ratio that have fewer issues. See this article: https://www.medicalnewstoday.com/articles/265215#Waist-to-height-ratio-better-than-BMI https://www.medicalnewstoday.com/articles/265215#Waist-to-he...

return_to_monke 4y ago

I do not find that BMI would be a good indicator, since (based on my own experience), people in the military are pretty muscular. BMI works for the average person but cannot differentiate between extra muscle mass and extra fat mass. on the topic of diversity, BMI often cannot be compared between ethnic/race groups: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4968570/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4968570/

bennettnate5 4y ago

They measure completely different things. BMI is a pure weight to height ratio--someone could have almost no skeletal muscle and have a "better" BMI than someone who works out daily and has heavy muscle density. They're strongly correlated in the statistical sense, but there's still a wide spread of body fat percentage for a given BMI. My guess is that they use different BMI metrics for men vs women when guaging fitness--that's how they keep things gender fair.

suslik 4y ago

BMI wouldn't be a good measure for this. The correlation might be strong, but very fit or muscular people (for instance, weight lifters, fighters etc) can have rather high BMI - and you really don't want to filter those out. Waist-hip ratio might be a good alternative measure.

arpinum 4y ago

If you look muscular and your BMI is too high, the military sends you to get measured with body calibers. BMI is just used for initial screening.