Why does BMI have units of kg/m^2 when we are three dimensional? Wouldn’t kg/m^3 or g/cm^3 be more accurate?
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A body with the least surface area and the most mass (density is constant) will be a sphere. Therefore, BMI measures how much of a sphere you are.
A body with the least surface area and the most mass (density is constant) will be a sphere. Therefore, BMI measures how much of a sphere you are.
It’s mass * height/volume
Since it takes your height into account, it’s like multiplying by height to get a cross sectional area of you
Just because something has a unit doesn’t mean it’s the unit that we’re used to thinking about. It’s your mass compared to your height squared, not your surface area or body cross-section area. As the top comment says, the ratio of your height squared to your mass seems to have some sort of correlation to health.
It’s mass * height/volume
Since it takes your height into account, it’s like multiplying by height to get a cross sectional area of you
It’s mass * height/volume
Since it takes your height into account, it’s like multiplying by height to get a cross sectional area of you
Just because something has a unit doesn’t mean it’s the unit that we’re used to thinking about. It’s your mass compared to your height squared, not your surface area or body cross-section area. As the top comment says, the ratio of your height squared to your mass seems to have some sort of correlation to health.
Just because something has a unit doesn’t mean it’s the unit that we’re used to thinking about. It’s your mass compared to your height squared, not your surface area or body cross-section area. As the top comment says, the ratio of your height squared to your mass seems to have some sort of correlation to health.
No. Healthy humans of a similar height should have roughly similar weights. We are all mostly water and all water weighs the same. There is some genetic variation in fat distribution and muscle development, but we should all be fairly average.
A male human can only increase his lean mass by about 10% through weight training without using steroids. So the whole “I carry a lot of muscle” argument is self denial.
Density isn’t really a good measure of how overweight you are, since being heavier doesn’t necessarily mean you are denser.
Others have pointed out that it’s a consequence of an arbitrary formula which has been shown to work. But it’s also worth asking _why_ it works.
From dimensional analysis, it’s a loose proxy for (the inverse of) your surface area to volume ratio by taking a proxy for your volume (your mass) against a proxy for your surface area (the square of your “characteristic length”). A shape that approximates a sphere will tend to have very low surface area to volume, and more convoluted / “branchy” shapes will have higher surface area to volume. It follows that the more volume you have for a given surface area, the rounder you are!
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