Poverty used to be roughly synonymous with not being able to get enough to eat. The poor kid had the sunken, sallow face and the skinny arms. Since it's inception in the mid-sixties, the poverty threshold has risen without taking increases in the material standard of living into account (it is basically three times the cost of nutriotionally-adequate yearly food costs). Today, the poor kids are the tubsters whose parents would rather buy high-starch foodstuffs that take little preparation time than cook actual balanced meals. Hence the contemporary correlation between the poverty rate and the obesity rate is a positive .45 at the state level.
The maudlin media has evolved with the changing waistlines of America's poor, with stories of how they must now eat themselves into obesity, since that's what is most available to them (thanks to the hard-nosed realists who retail in the realm of the underclass, carrying greater quantities of the stuff their patrons actually buy).
Lugubrious reporters try to paint it in Marxist terms. Yes, it is implicitly implied, America's poor have enough to spend on food, but only enough to buy (lots) of junkfood. Their economic disadvantages keep them from eating enough fruits and vegetables. That's absurd. A four-serving size can of green beans costs less than a king size Snickers bar does.
Might it be, instead, that the poor tend to be more impulsive and have a greater time preference than the rest of society? This immediate orientation means the good taste now weighs (heh) heavier in the mind than health benefits foregone, relative to the longer-term orientation of the burgher who foregoes the burger for the salad. More bluntly, those of lower intelligence are likely to eat less healthily because the realization of the benefits that come in doing so are difficult to pinpoint and only accumulate over time, whereas the sugary stuff tastes good now. Similarly, they are less likely to engage in physical activity for the sake of the health benefits derived in doing so.
The self-destructive tendencies of the duller underclass illustrate how the more intelligent, affluent a society is, the more libertarian it can afford to be in its social and economic frameworks. As a society trends toward Idiocracy, its governmental structure necessarily becomes more authoritarian and increasingly intervenes in the lives of its citizenry, through regulation of personal behaviors, wealth transfers, and the like.
Yet, at the state level, the inverse relationship between obesity (p6-7) and estimated IQ is only a modest .22. The fat numbers come from Trust for America's Health August 2007 report, in which obesity was calculated using the Body Mass Index. The BMI can be problematic, as it considers an NFL linebacker with 8% body fat to be obese.
The BMI shortcomings are personal. When I was in ROTC my freshmen year, I finished first or second in the program on the two-mile run portion, consistently in the 10:40s, in every monthly PT out of 80 pretty fit guys. Yet at the weigh-in I was consistently deemed overweight with a BMI of 28 (I'm 6'1", 210 lbs). I've plenty of problems, but physical fitness definitely isn't one of them.
Still, my vain personal bone aside, these imperfections are going to be sufficiently smoothed out over entire state populations. Athletic Coloradoans might prefer mountain biking more while fit Floridians enjoy pumping iron on the beach, but the overall distortion should be marginal.
Why, then, the modest relationship between fitness and intelligence? One caveat to the IQ estimates using NAEP data is that they are a measure of current adolescent intelligence, a glimpse of the intelligence levels that can be expected in the future. In states that are relatively demographically stable, this caveat may not mean so much. In areas such as the Southwest and the South, it becomes more important.
Fortunately, the study included, for the first time, rates of heftiness among children ages 10-17. Falling smack in the middle of that age range are the 14 year-olds who constitute the NAEP results used for the IQ estimates. The inverse relationship between corpulence and IQ among these youngsters is a much more robust .60.
Meh, maybe it's just a coincidence? But consider the Vietnam Veteran IQ estimates that come from the baby boomers who are now running the country. The inverse correlation between those estimates and obesity rates among adults is .62, almost exactly the same as the relationship between the two attributes for teenagers. The Vet and NAEP estimates are similar, but not identical. Some of this variance is surely attributable to changes in states' composition over the last four decades, as the Trust for America's Health study and the aforementioned relationships suggest.
David Brooks, who, if he'd paid a little more attention to the predictive power of IQ in terms of determining the viability of a liberal democracy, might not have been one of the most unrestrained, vociferous supporters of the Iraq plunder, says paying attention to IQ reduces us to obsessing over "electrical impulses and quantifiable pulses". Uh, the sociological and statistical work on IQ in books like The Bell Curve, of pundits like Steve Sailer, and papers like that of VCU's Professor McDaniel, do not deal with this much at all.
Well Mr. Brooks, in addition to the material standard of living, infant mortality, wealth, life expectancy, criminality, employment, educational attainment, and livability, among others, comes the relationship between IQ and physical health as measured by tubbiness. If IQ was meaningless--essentially a randomly assigned number--it wouldn't correlate with anything. If it was merely a rough proxy for some other measurable trait, it wouldn't relate to some variables more strongly than whatever that it is putatively proxying for does.
Virtually every way it is looked at, IQ correlates positively with favorable social variables and negatively with pathological ones. Human resources are of crucial importance to any institution's success. It's past time we looked at IQ as a valuable human resource that should be cultivated.
People like Brooks want to kill the idea of innate differential intelligence (or temperament, physical dexterity, etc) because their ideologies are at essence institutionally biased. The neocon right (free markets, equal representation, and democracy) wants to claim an equal playing field will lead to equal opportunity and maximum prosperity. The big government left (redistributive income, universal healthcare, affirmative action) wants to claim it can direct equality and prosperity into existence. For both of these broad ideologies to work, people must be blank-slates responding identically in identical situations. That's becoming increasingly difficult to maintain in the face of quantitative sociology and advances in human genetic sequencing.
Feeling threatened, they're lashing out sophomorically, asserting that everyone who is anyone knows--knows!--IQ is bunk, so why are you thinking about it? NPR's Talk of the Nation ran a ridiculous 'hit segment' on the putative moribundity of IQ several weeks ago that was frustrated over and over by callers who persistently took more moderate positions on the subject.
If these blank-slatists, especially on the neocon right, believed IQ testing, correlation, and research to be worthless, they'd allow it to occur without protest. Just like irrational racial discrimination, right? The market will punish it. Of course, the market rewards it because it brings rewards in the market, which is why companies try to sneak in things like the Wonderlic test wherever they can (my employer uses them) even with the sword of Griggs v. Duke Power hanging over their heads, why the military and academia make extensive use of aptitude testing, and why business moguls like Bill Gates have leveraged it to attain greatness.
As maintaining an appropriate weight becomes more of a choice (in the sense that almost everyone has the ability--although not necessarily the genetic predisposition--to choose whether or not he will become obese), intelligence will become an increasingly important factor in determining obesity rates in the first-world. Part of the strategy employed to deal with burgeoning healthcare costs should be to take steps to increase the average IQ of the population through eugenic birthing incentives (and the ending of disincentives like the EITC and the child tax credit), changes in the tax code, a restrictive merit immigration policy, the liberal use of genetic testing and sperm banks, and the like.