Wednesday, February 13, 2008

Correlation versus Causation

I have a friend-of-a-friend who refuses to drink diet soda, on grounds that it makes you fat. The evidence? The fact that so many diet-soda drinkers are fat. Our friend-in-common refers to this guy as "the Caveman." I think the Caveman would appreciate this article, which notes a statistical correlation between drinking diet soda and having metabolic syndrome (a combination of cardiovascular risk factors including abdominal obesity and high blood pressure):
The scientists gathered dietary information on more than 9,500 men and women ages 45 to 64 and tracked their health for nine years. ... [S]urprisingly, the risk of developing metabolic syndrome was 34 percent higher among those who drank one can of diet soda a day compared with those who drank none.
Surprisingly? I'm not surprised at all. Fortunately, a co-author of the study at least hints at the most likely explanation: "Why is it happening? Is it some kind of chemical in the diet soda, or something about the behavior of diet soda drinkers?" I'm betting on the latter.


Anonymous said...

I'm going out on a limb here, because I haven't read this book, but a friend has, and I read an excerpt from it as well as other studies.
A good read on "diet" or even processed food:
Excitotoxins: The Taste That Kills
by Russell L. Blaylock
Americans especially have bought into the diet lie. Excitotoxins (sugar substitutes, additives, preservatives, etc.) not only screw up your metabolism, they mess with your nervous system, starting with your five senses. Aspartame (sugar substitute), over a period of time, literally causes brain damage. The "made from sugar" substitutes with no calories is still sugar. People use it like it's going out of style and wonder why they end up with diabetes. It's still sugar, folks. We have anesthesized ourselves with these chemicals to the point we can't think straight because we literally can't when we have neurotoxins in our brains. Diet soda is worse than alcohol. At least wine has antioxidents and beer has redeeming qualities as well. Thumbs up for "the Caveman." He's the hero of the day for saying "screw you" to the diet soda fad.

Anonymous said...

The only way I could stop drinking diet soda was by convincing myself that Aspartame, etc. is indeed poison. How did it get approved by the FDA? Donald Rumsfeld was the CEO of Searle at the time that it was seeking approval from the FDA. Why was a former head of the defense department turned into a head of a chemical corporation? Did his political connections have anything to with it? Rumsfeld became unbelievable rich from that association. You are responsible to a large extent for your own health, but as long as people can enrich themselves at the public's expense it will happen. Since the corporations control the government to a large degree, you can't count on the government for protection either. The whole thing stinks, like cigarettes. I can't vote for Obama because he smokes. If he is that dumb, he's not getting my vote.

Anonymous said...

What's happening is that the diet drink is effectively lowering the 'price' of obesity and so we are getting more of it, as any economist would predict. It works like this: if I know I am going to put on half a pound by drinking a can of cola, it isn't worth it to me. The benefit I get from enjoying the wonderful cola flavour isn't worth the cost of the weight gain. The pleasure is too short lived, I might as well forego it and stay thin. But if I can drink ten times as much cola for the sme weight gain, it becomes worth the cost. The incentives are different and my behaviour adjusts accordingly. I don't think it is a surprise that the obesity 'epidemic' comes at a time when the sale of low calorie food is so high.

Anonymous said...

This is Anon. Feb. 13, 3:36 PM. I had to giggle yesterday morning at my little boy's Valentine party. One of the obese mothers asked the adults, "Who want's a diet coke for breakfast?" Go figure figuratively and ruin your figure.....

Simon Clark said...

I used to drink diet coke, but I have since changed that preference to regular coke. My original decision was made under some assumptions:

It was at least very slightly better for one's health than regular coke.

It cost the same monetarily as regular coke.

It tasted no worse.

The second assumption I believe was and still is true. A can of diet coke usually costs 60p, as does a can of regular coke.

The last point, I believe, is not in fact true. I am fairly sure I can distinguish between the two products by taste alone and that I prefer regular coke. I have also discovered two further factors in my decision: the red can looks nicer than the silver to my eye and drinking diet coke can incur the derision of, at least male, friends who believe it to be an unmanly activity (presumably, even if this factor is replicated in others, the disincentive to drink diet coke will be absent or reversed in females). This is something I have learned and the primary cause of my change in decision.

The first assumption seems to be in doubt, so my decision seems to be increasingly correct.

Simon Clark said...
This comment has been removed by the author.
Adam said...

I would bet AGAINST the diet soda drinker's behavior as a major factor in their developing metabolic diseases. The evidence seems to be mounting that various sugar substitutes and delivery devices circumvent biological mechanisms designed to help insulin response and metabolization.

For example, the fiber in whole grains (probably, could be some other part of it, regardless, the whole grain) limits the sugar intake rate to the bloodstream and includes enzymes that slow the insulin production rate. Crush and bleach the flour, and you have a set of carbohydrates (not necessarily evil) that can now impact the sugar concentration in the bloodstream more quickly and cause insulin levels to fluctuate wildly. It is the fluctuation that drives insulin resistance as the body is forced to constantly produce buffer chemicals. Enzymatically we become the meth addict forced to take downers to sleep. Once the body develops insulin resistance, you are basically a type II diabetic.