Friday, September 12, 2008

Friday Rant - And my celebrity BMI is...

In this That's Fit post, there's a link to a site which lets you type in your height, weight, and gender and it will provide your BMI (body mass index, the percentage of body that is fat). The fun spin is that it will tell you what celebrity has the same BMI as you.

You remember those handy dandy charts on your doctor's walls, the ones where you look at your height and cross it with your weight and it tells you whether you're normal, overweight, or obese? That's BMI. And I have a major problem with the system.

Here's the thing...some people are clear cut. Obviously obese, obviously underweight, that kind of thing. But what this doesn't take into account is dimensions and how fit someone is. Because someone who's 5'5", 160lbs and very fit is going to come out with the same BMI as someone who is 5'5", 160lbs and hasn't exercised a day in their life. But obviously their fitness and health is going to be very different (for the means of this random example, assume their diet is the same), and they're going to carry that weight differently too. Plus, all that muscle is heavier than fat (true, though lots of people use it as an excuse for gaining weight).

So, for example, I type in my vital stats into the celebrity BMI calculator. Who do I come out with? Queen Latifah. Now, don't get me wrong, she's got a great hourglass figure. But I also think that she's considerably heftier than I am. Part of the problem is that she's also 6 inches taller than me, so to have the same BMI, she'd have to be a lot heavier, proportionally. So to be more accurate, they shouldn't just pick a celebrity with the same BMI, but one who's at least a bit more the same height (6 inches? Come on!).

The alternative gaining ground is the waist-hip ratio. Basically, divide your waist circumference by your hip circumference, with the ideal ratio for women being below .80. I like this one much better, because it does take fitness into account (if you exercise and eat appropriately, you're more likely to have a lower ratio). And of course, some people (the classic "apple," a term which I hate) will have more of a risk because they hold more weight around the middle (this has been shown with several studies to increase the risk of diseases and early death, unlike the "pear" which doesn't seem to increase risk).

The most effective way to determine BMI is DEXA, which is expensively done at a radiologist, or water displacement, which requires total immersion in a pool. So neither are all that realistic for the basic population. Calipers are also effective, if done properly. And that's the caveat, because it's really easy to do improperly. Given the impracticality of the former two, and the ease of tester error on the latter, waist-hip ratio is one of the easiest methods we can use to determine our own BMI (there's also the electrical impulse machine, but really it's not the most effective, plus it requires equipment).

I understand that we're trying to be all healthy, and that's important. But I think that we've found these easy way to slide people into categories, without really looking at the specifics or how people are different.

16 comments:

MizFit said...

I agree with the BMI thing as manymany times Id have been classified as overweight. I weigh a lot more than one would think merely because of the heaviness of muscle.

I may have to check out those stats and see who I am.

love the Queen but am confused that she's taller than you and you 'got' her as your match.

off to see into what category they wanna cram me.

Miz.

WeightingGame said...

that chart reminds me of the thing on the back of panythose packages that tell you if you're a large or an extra-large.

MizFit said...

huh.

Im salma hayek (ak? shoot Ive already forgotten)

Ill take her tatas I guess but we look nothing alike.

(to her delight and my chagrin (rimshot!))

The Lethological Gourmet said...

Weighting, you're totally right, it does look like the pantyhose chart!

Miz, Salma Hayak, oooh! That's a good one. I took 10lbs off, just because I was curious who I'd get. Oprah. At least she's more my height, though still a little taller. But then, 10lbs down is the lightest I ever was, and hard to maintain, so I'm perfectly happy where I am :)

Leah J. Utas said...

Queen Latifah. Don't know what to say to that. I'm about 5'4" and I'm guess I'm rounder than I think I am.

The Lethological Gourmet said...

Or their system is just broken :)

JavaChick said...

I also go Queen Latifah. And I don't think I look as hefty as she does either. But perhaps mine eyes deceive me.

I entered my goal weight and it came back with Kelly Clarkson.

Charlotte said...

So of course I had to try it. I got Natalie Portman. I'll be ruminating over that for the rest of the day now... ("Apparently I should look like Natalie Portman. So how come I looking NOTHING like Natalie Portman? What do I need to do to look like Natalie Portman??") Aggggh! I should really know better.

And I'm with Leslie about the pantyhose sizing chart:)

jeffg said...

BMI is useful on a macro level, ie to look at a group of people and make statements about those people.

BMI isn't very useful on an individual level, as it makes a lot more assumptions than other common methods.

IMO Bodyfat %age is the best way to go, although common/accessible measurement techniques are highly flawed (most people are *not* properly trained on calipers, even if they think they know what they're doing ... and those electrical things are notoriously flakey. Hydrostatic testing is good but that's out of the reach of most folks)

I can describe multiple situations where I'd have the same BMI but wildly different BF% (e.g. the last time I was around this BMI, my BF was ~10% lower than it is now).

The one thing that I will say in defense of BMI though is that for "the average person" it isn't *that* terrible for a quick assessment, I just don't like people that read too much into it (insurance, doctor, etc).

The Lethological Gourmet said...

Jeff, that is a really good point. BMI is useful on a macro level, and it's more on the individual level that I take issue with it. And even the flaky electrical impulse thing is really far off (for me), I think. But it is when it gets taken to an extreme, used for insurance rates, or using BMI to ban people with a high BMI from eating in restaurants

jeffg said...

Don't get me started on that ban.

So I have one of those Tanita scales. For me personally it seems to be consistent but not accurate, if ya know what I mean (in that it's off, but off by a consistent amount). To get that consistency I use it in an *extremely* consistent manner - certain things seem to cause it to get a bit wild.

The gf can't really get the BF% part to be consistent at all, no matter what she does.

A friend of mine has the same scale and the situations that cause inconsitency for me are what causes it to be consistent for him and vice versa.

So it's definitely a case of YMMV

Oh and BTW, on the topic of waist-hip, for a woman the golden ratio works pretty well ;) Well, not exactly but close to/little less than 0.7 is a pretty universal number throughout time, culture, etc. I forget the #s for men, but it's pretty close to 1.0 (duh). This is purely from a subconscious aesthetic angle and not necessarily fitness, but if you look into it, it's interesting how the two intersect in these more universal type cases (but 'fitness' in these cases aren't always the same as 'fitness' for our modern society)

Dr. J said...

I came out kobe Bryant :-)

Anonymous said...

The BMI thing gets my goat. The non-celebrity version of it says I'm borderline obese(I got Queen Latifah too, by the way, on the celebrity version) - I am 5'3", have a waist that's 30 inches, and can do 60 push-ups in 2 minutes. OBESE?? (My waist/hip ratio is less insulting... it's 6.9). I am very strong. I also have some nice hourglass curves. :) I am NOT fat.
By the way, not only are muscles heavy, but so are healthy bones. (Which is something that I find extra scary about anorexic people - some of that weight they're losing is FROM THEIR BONES. Yiikes.)
Anyway, I've wanted to rant about BMI for a while - thanks for letting me do so!
Sara

Anonymous said...

Oh, and no insult meant towards Queen Latifah - I think she's fantastic (and kind of intimidating). But I don't look anything like her, honestly!

Anonymous said...

Oh, and those 60 push-ups are "man-style", of course... though calling them that is almost as insulting as being called obese. I can do more push ups than most men! Why "man-style"?
*finish rant* :)
Sara

michelle of bleeding espresso said...

I hear you on the BMI thing; frankly, even looking at the scale can be upsetting for someone with actual muscles (and, as Sara notes, healthy bones). I'm sure it's a great general (very general) guide, but like you said, it just doesn't take enough information into consideration to really be useful.

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