Tuesday, July 03, 2007

BMI is a curseword

Okay, so you've heard of the BMI (Body Mass Index), right? Today I was bored so I punched my stats into the calculator and it said that I am at the tippy top of "normal." Krrrr. I suppose I should have been pleased that I was down from "overweight."

Well, then, I took boredom to a new level:

If I figure that I'm actually 5'9" rather than 5'8.75678", which is closer to reality, my range for "normal" is 125-165.
Dream on. Okay, for me that's not a dream. It's a nightmare. I have some pictures of when I weighed that little. After the evil boy who I let make me so unhappy I cried so hard I barfed for about three months straight and even after that it took me almost two years to get back to a normal weight. Ryan doesn't like seeing any of those pictures because he said it makes him so sad.

Speaking of Ryan, he is 6'2" and his "normal" range is 145 to ... who cares. 145? He'd have to lose fat, muscle, bone mass, and potentially actual entire bones to weigh that little. So, after stomping around the room mumbling that it was the stupidest system ever, I did some more research about interpreting the results:

My distillation of the site is:
  • BMI is a cheap and easy way to predict if someone has a high level of fat and is therefore a high risk for developing heart disease
  • It's a range to take into account body type/gender/etc.
  • It's not that effective for people who are highly athletic and muscular
  • It's not that effective for older people who have less muscle mass
So, I guess if you're average height, average build, average muscle mass, it's a good predictor for you. As for those of us who are a little larger (or smaller) naturally, it's not that great. So quit feeling badly every time you walk into your doctor's office!

Other things to consider are:
  • waist circumference (also slightly variable I would guess based on your size)
  • other risk factors
If you have two of the above, plus the high BMI even though you are athletic, etc. chances are you have a significant amount of body fat. Or at least that's how I read it.

But don't take my word for it!


Ann Marie said...

body fat percentage is a much more accurate measurement of how healthy you are, but it's cumbersome. The best way is to have someone trained to use calipers measure it (ie a personal trainer, etc). The scales you can buy that measure electrical impedence aren't that accurate for a single measurement but they're good for checking trends.

shoeaddict said...

Hey Kate- wanted to see how you're doing. How's the meds? How's the no cheese?

Email me or come over and read my newest post!

HOpe you had a good 4th

Kristen xoxo

jUnEbUg said...

I hate body fat measurements or percentages or whatever. I hate all things weight-related. I, too, am 5'9" or somewhere close, and I ain't nevah weighed 125. Maybe in the 6th grade. Whatever.

Also, tell me about your reading lists over there in your right column. I am a SERIOUS reader!!

Tim said...

Yeah, Dad and I have been talking about the Thomas legs a lot recently. They're apparently Welsh. And we should be carrying sheep around with the freakish amount of muscle mass we have. My BMI is within .6 points of being overweight. So I think we might be seeing a familial trend here.

Weight is such a stupid thing anyway. It's pretty much meaningless. Of course, it would be nice if there was a simple way to gauge your relative health.

Julie said...

Totally off topic, I finally did the parenting survey on my blog!
And I was surprised to find that my BMI was at the top of healthy range when I started this Weight Watcher's thing and now my goal is the bottom of my healthy BMI. We'll see whether I make it there, because it's pretty trim. Of course, I get to round up to 5'10" (I'm 5'9.5") so my low point BMI is 139, which is pretty low for me, but not anorexic or anything.

Sarah said...

Hi Kate-
I saw your comments on Kristen's blog (shoe addict,) so I was surfing the net at work and thought I would stop by to say hi. I know what you mean about the BMI-I think my low end is like 110 (I am 5 feet.) 110? Yes, that would be possible if I quit my job and school and went to the gym for 4 hours a day and only ate lettuce. Anyway, hope you have a nice weekend!