Signal to Noise

I have always been obese. Well, probably not really, I was probably within statistical norms for a few minutes after birth. And when I say that I am obese and have been for the last twenty years (which is closer to accurate) it is based on the body mass index.

I would also like to point out that at various periods during this time I was

• Playing competitive (let’s call it somewhat competitive) soccer three times a week
• Biking 200+ km per week
• Playing hockey (again call it semi-competitive) five times a week
• Practising taekwondo four times a week
• Generally being fit and outdoors and happy

My point being that I am a big guy and have been for a long time. I was fortunate enough to have a bicycle built for me by Gilles Bertrand at one time and I wanted a particular frame. I was told in no uncertain terms that for such a bike I would have to weigh less than 200 lbs or I would greatly lessen the life of the bike. I was a “gram weenie” far more than was healthy for a guy my size. I am far better described as torque-enabled or gravity-enhanced than as a mountain goat. I suffered up every hill that my more svelte friends ascended with (what appeared to me to be) the greatest of ease. My only revenge was the downhill where gravity and a tuck were my friends.

So, back to being big–I was and am. My BMI has always been high. To be fair, I just checked the scale and when I got down low enough to buy the bicycle I was only “overweight” on the BMI scale. I biked over 2500km that year around Ottawa.

I have come to hate the BMI. I hate being classified as being so overweight. “[Because of its] ease of measurement and calculation, it is the most widely used diagnostic tool to identify weight problem within a population” (Wikipedia). And there is nothing more comforting than a simple number when making a diagnosis, especially when the number is the result of a mathematical formula. Those things are great.

When I came across a NPR article called “Top 10 Reasons Why The BMI Is Bogus” I could not have been happier. I read it three times just to cheer myself up. Hey, I am still a big guy. I am bigger than I should be given my current lifestyle and physical ability but I would appreciate not having people rely on an abstract number that assumes uniform body composition across all members of a population and uses poor mathematics and statistics (as well as an early 19th century understanding of physiology) to classify individual fatness–particularly when the inventor explicitly said it was not suitable for that purpose. For the record, here is the top ten list in abbreviated form:

1. The person who dreamed up the BMI said explicitly that it could not and should not be used to indicate the level of fatness in an individual.
2. It is scientifically nonsensical.
3. It is physiologically wrong.
4. It gets the logic wrong.
5. It’s bad statistics.
6. It is lying by scientific authority.
7. It suggests there are distinct categories of underweight, ideal, overweight and obese, with sharp boundaries that hinge on a decimal place.
8. It makes the more cynical members of society suspect that the medical insurance industry lobbies for the continued use of the BMI to keep their profits high.
9. Continued reliance on the BMI means doctors don’t feel the need to use one of the more scientifically sound methods that are available to measure obesity levels.
10. It embarrasses the U.S.

(from NPR)

Aside from the conspiracy theory tilt of the last three points I couldn’t agree more. There are lots of fat people and there is little argument that we (Westerners) are becoming fatter. I am a big believer that the reasons centre around eating too much and exercising too little. I know, that is the kind of rocket science that you just cannot believe I am giving away for free, but there it is: more calories come in than go out so we get fat. Our diet has increased in sugars and fats so the calories go up. We are more sedentary so we are burning off fewer calories. These problems are serious enough without confusing the issue with poorly constructed formulae and statistics to prove the point.

When my wife was taking some courses in nutrition at UPEI she would often bring home nuggets of wisdom that tended to cause us to eat food closer and closer to alfalfa. Generally, when I heard that she had picked up a tidbit from class I would shudder at the pending switch in foodstuffs. There is one occasion (well, more than one, but I am going to write about one now) when I enjoyed the nugget of wisdom. It went something like this

there is a study that has shown that men who wear black socks are more likely to have heart disease

This would be a good time to point out that I do not know if this study exists and if it does I do not have a reference to it. The point the professor was making is that some types of studies are “epidemiological studies” that attempt to correlate various factors of human populations in order to discover causal relationships between these factors. In other words, get a bunch of people and look at what is the same (or different for that matter) for that bunch of people and see if there is a reason for for the sameness (or difference).

If it turns out that men with black socks are more likely to have heart disease (which might be true) it does not mean that black socks cause a higher incidence of heart disease. There is a correlation but not a causal relationship. Another favourite of mine is the assumption that the crowing of a rooster causes the morning to arrive. The rooster always crows before daybreak and the day always comes. That is a slightly different argument that suggests timing implies a causal relationship (post hoc ergo prompter hoc) but I like it as an example, even if it does not prove anything about heart disease or epidemiological studies.

All of this would mean very little if it were not for the fact that I was catching up on XKCD and came across the above comic a couple of hours after I had a relatively long discussion with my aforementioned wife about High-Fructose Corn Syrup and the correlation (though potentially not causal relationship) with North American obesity. You may be jealous or relieved you do not have such conversations with your partner–I think you should be jealous, but that is just me.

Anyhow, I am still no fan of HFCS and I am not going to wear black socks. You have been warned.