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.
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