Sunday, November 2, 2008

Week 52 Wrapup

I ran Monday and Wednesday of this week, but then the cold that's been being passed around by our family made its way back to me. So, I took the rest of the week off because I didn't want to risk making myself sicker by over-exerting myself.

I've been talking marathons with some cousins on my Dad's side and some cousins on my Mom's side. One group has looked at things time-wise and determined that the Ogden Marathon in May is the best target. The other group is thinking that St. George in October is probably best. I'm committed to helping both groups, since they're first time marathoners, and doing whatever it takes to do it with them. I've also just committed to doing the Running From An Angel Marathon in Boulder City January 3rd with Scott.

That's 3 marathons in a year. It's not the fact that I'm committing to 3 marathons that's insane. What's insane is that I'm looking at that schedule and thinking "Yeah, that's totally reasonable" instead of "Zounds! What am I thinking?!". Something has clearly snapped in my head. I'm also still planning on doing the Ragnar Del Sol in February somehow. And, last night as I was going to sleep, I was thinking, "Boulder City will be too hilly for a good time, and those other two I'll be obliged to stay with the first timers, so I won't have a good time there. Maybe I should work in a 4th for a time trial somewhere in the year." Yeah, something's definitely snapped.

BMI Rant

This week, the moving average of my weight slipped under the 25 BMI threshold for the first time. 25 is the most commonly accepted boundary line between the "normal" and "overweight" categories.

Now, BMI is sort of a controversial measurement. If you read around the internet, you're bound to find a lot of whining about the BMI and how it doesn't really apply in real-world situations. Usually, this whining is done by fat girls who are trying to be in denial of the fact that they are fat. There have been thousands of blog posts out there railing about the fact that "The BMI said I was overweight, but look at me, I'm healthy", "Real women have curves", "The BMI says Arnold Schwarzenegger's obese, so it must be wrong when it tells me I'm obese". Then, when I see actual pictures of the people doing the ranting, 90% of the time I'm thinking, "Well, you are fat..."

I'm not qualified to judge the health of those people or their ability to lose weight, but those things are really separate from the BMI anyway. For the sake of those people and anyone else interested, I'm going to now teach a mini-lesson on the proper use of the BMI measurement:

All the BMI is is a formula that correlates a person's weight to the square of their height. The formula was invented by a Belgian in the 1800s to try to find a way to accurately compare the weights of people of different heights and develop statistics of a population as a whole. The whole idea of assigning classifications to the numbers is a relatively recent phenomenon, and is based on finding the correlation between a population as a whole with high/low BMI and the increased risk of death or illness across that population as a whole. So, we're talking about really two separate but kind of related things. One's a formula that attempts to compensate for variance in height (yet fails, because at really short or tall heights the numbers get really skewed), and the other is classification of populations into categories depending on what number the formula comes up with.

To review, the only thing a BMI number really is is a ratio of your weight to the square of your height. Period. Full stop. Any interpretation of that number is a whole separate process.

On to the interpretation part of it. The current numbers used to define what your BMI "means" are from WHO, and classify under 18.5 as "underweight", above that but under 25 as "normal", 25.0 to 29.9 as "overweight", and 30+ as "obese" (where I was when I started this, by the way). The CDC in the US didn't use the WHO numbers until 1998, and previously had a higher cutoff for normal (27.5 or somewhere around there). So, ten years ago, millions of people in the US suddenly became overweight. Those people didn't suddenly gain any weight or increase their mass. Their body composition didn't change. Their health didn't change. They were just suddenly called overweight. It's kind of funny imagery, but it should just serve as a reminder that we're really only talking about statistical classification here.

I do believe that there would be less of a BMI backlash if the labels used were something other than "normal" or "overweight" or things like that. If the labels were to be "average" and "above-average" and more non-judgemental sounding things like that, it might be better accepted. The problem with using "normal" anywhere in your labelling is that you automatically stigmatize anyone stuck with the "abnormal" label.

Some other things about BMI:

BMI is not a predictor of individual health, although there is strong statistical correlation between high/low BMIs and poor health. If you are tall and very muscular, yes, you might be in the obese BMI category, but nobody will make the mistake of calling you unhealthy.

BMI does not tell you body fat percentage. Your percentage of body fat is a much better indication of whether you're unhealthy or whether or not you're "fat". It's also going to have a much bigger impact on whether you look fat. I know plenty of people who have BMIs lower than I, but have a higher fat percentage, or an uneven distribution of fat around the middle or the posterior. Looking at those people, you'd probably call them fat. But, even though my BMI's higher, you'd be a lot less likely to call me fat (now, anyway).

BMI is not a clinical diagnostic tool. Looking at someone's BMI without looking at the person behind it doesn't tell you anything about that person or about their health. You have to examine the whole person and their health history, symptoms, body, et cetera before drawing any conclusions rather than make any judgement based on a number.

So, if anyone is using a BMI diagnostically, they should be slapped. Any doctor that tells someone that they need to lose weight just because their BMI is over 25 should be slapped, just like any doctor who misses obvious signs of an eating disorder because they won't look past a "normal" BMI of 21. An insurance company that rerates a person into a higher risk class just because of a high BMI without considering other health factors or body types or measurements should be slapped.

The other side is that anyone who gets really hung up on their own BMI should be slapped. Anyone who feels stigmatized by the label they've been assigned out of the BMI categories should be slapped. It's a number and a statistical measurement, not an assessment of your value as a person, so get over it. Yes, your number puts you in the "obese" category. Yes, being in that category makes you statistically more likely to die or be sick. However, those are only predictors of populations as a whole, and your individual health can only be adequately assessed between you and your doctor.

There. Rant over.

Now that I've got that out of the way, though, I confess that I feel much better knowing I'm now a normal person. All you other people with BMIs outside the 18.5-25 range can suck it.

5 comments:

Derek said...

My 5'5" and 155 pounds give me a 25.8 BMI, and make me overweight. That's why BMI is wrong. When I get down to 150, BMI will be a good way to measure my health.

Supercords said...

Aaron, you haven't snapped. You've simply gone over to the other side. It sneaks up on you, and before you know it, you're one of those guys in short shorts who you used to make fun of. I predict we will all be on this side one day, the only question is who's coming over next?

Let me know when you want to join me on an ultra.

Aaron said...

As far as I'm concerned, ultras are still in that category of "That's insane, and there's no way in all creation that I would ever consider doing such a thing".

So, yeah, give me another month or two and I'll probably change my mind on that, too.

Gords said...

Marathon is Cathi's favorite. The Ogden canyon is very scenic and has a nice decent. You might see her there next year.

Agreed on the BMI rant. Although most really strong people aren't in the "Normal" range. Usually the really tough folks are "Obese". So there are trade-offs. But for overall health and fitness I think normal range is better. Nice job getting there.

Gords said...

[The Ogden] Marathon is Cathi's favorite.