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Humans
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Let's talk about irrationality.
To what in reality does IRRATIONALITY refer?
I'm not up to a definition just at the moment, but the elements of a definition are contained in the following:
- willful disregard for facts
- belief in things for which there is no evidence
- belief in things for which there is contrary evidence
- willful rejection of a conclusion of a valid argument
There are probably other things, as well, and I may even be working on the wrong level of abstraction for a really useful definition, but I'm about to make accusations of irrationality and I want to be clear what I'm talking about.
It goes like this. There are a lot of fat people out there. If you're an American, the odds are something better (or worse) than fifty-fifty that you are overweight, and one in five of you is obese. The source of these data is the Centers for Disease Control. There are lots of reasons for people to be fat, but mostly the reason is that they eat too much and aren't active enough. But there is a significant subset of the population who, irrationally, don't want to believe that. They would prefer to believe that fat is in their genes, and they don't have any (or not very much) choice about it.
If you believe that, and you don't want to disabused of the notion, stop reading now. Otherwise, read on.
The claim that people's problem with weight is genetic is right up there with the claim that IQ is genetic, and demonstrably wrong for a similar reason. Just as IQ's have risen dramatically over the past thirty or forty years, so the fraction of the population who are overweight has increased dramatically as well. Unless the genetic makeup of the population has changed in astonishing ways, then these changes must be due to changes in lifestyle. And I don't think there's any evidence for such massive genetic change, even in Canada where we have a very high proportion of immigrants (something like 20% of the population wasn't born here, and more power to them for having the good sense to come join us.)
In 1960-62, 43.5% of the US population was overweight, and 12.8% was obese. In 1988-94, 54.6% of the population was overweight, and 22.6% was obese! That is, the fraction of the population that was obese nearly doubled in thirty years.
This fact is undisputed, and inconsistent with the claim that there is (The New England Journal of Medicine -- January 1, 1998 -- Vol. 338, No. 1):
a fairly stable set point for a person's weight that is resistant over short periods to either gain or loss, but that may move with age. According to this concept, changes in feedback mechanisms under the control of the central nervous system alter both appetite and metabolism to defend the set point and prevent large fluctuations in weight.
Another way of putting it is, if you are obese today, there is nearly a 50% chance that if you had lived forty years ago, you would not have been obese. This is inconsistent with the claim that most obesity is due to genetic factors. Ergo, most obesity is not due to genetic factors, twin studies that tentatively suggest the contrary notwithstanding.
The issue of rationality here is: do you believe a large-scale demographic shift that indicates that most obesity is not due to genetic factors, or do you believe a notoriously difficult and disputed methodology (twin studies) that suggests there might be a genetic component? I contend it is irrational to do the latter: that the long-term data prove beyond reasonable doubt that the odds are very good that if you are obese, it is because of your lifestyle, not your genes.
The long-term data are available from the CDC, in a downloadable PDF file.
In general, I think it is important to keep in mind such large-scale integrations over whole populations when evaluating facts. It's hard to formulate general rules for this sort of thing, but the basic idea is that if intense study of a small population suggests one thing, and careful observation of the population at large suggests another, then the results of the intense study are probably wrong, over-stated or misleading.
I've written throughout that being overweight is a problem? Is it? Or is that just a myth foisted onto us by Holywood and the diet and exercise industries? I can only speak for myself, but as a formerly obese person (weight: 220 lbs, height: just under 6 feet, BMI=30.1) I can say that being really fat cuts you off from a lot of good things. You tire easily. You fall harder when you fall. You run out of steam quickly. And for myself, while I didn't look nearly as fat as I was (which is a bad way to be fat, as it means you've got a lot more internal fat) I like the way I look a hell of a lot more now, a year and a half and 45 lbs later.
Nor is losing weight that hard. |
