A Rambling Response on Obesity

Last week, Ezra Klein accused me of not having talked to more than a handful of obesity experts.  Alas, had he done a little googling, he could easily have discovered that I was interviewing public health experts about obesity back when he was, by my count, finishing up Freshman comp.  I've paid quite a bit of attention to the subject over the years, and over the years I've changed my mind about it quite a bit, in part because some of the science has changed, and in part because I've looked at different science.  I don't agree with Paul Campos about everything, but I do agree with some of his core propositions:

  • Study after study shows that most people are unable to lose more than a small percentage of their body weight and keep it off without major surgery
  • There is evidence to show that this is physiologic rather than pyschological--it is nearly impossible for very heavy people to simply "eat less and exercise more" to a "normal" weight (given that 2/3 of the country is overweight or obese, normal weights, aren't.)
  • The fact that this often operates through the appetite system does not mean it's "all in their heads" or a lack of willpower.  Appetite is a signal as powerful as thirst or pain. Most people can't ignore it.
  • The largest environmental determinant of this trend is probably simply cheaper, tastier calories, which will be very hard to reverse
  • Much of the panic about the obseity epidemic comes from lumping all weights together--everyone over a BMI of 30 becomes an obese people with high relative risks for various diseases, even though the whatever health risks exist among the lower overweight ranges are not anything like the dire health effects of morbid obesity
  • At the moment, it's unclear whether there are any adverse health effects associated with overweight or even mild obesity, and to the extent that there are adverse effects, it is also unclear whether they are a result of the body fat, or a proxy for fitness levels and eating habits
  • The emphasis on the visible proxy (obesity) is counterproductive in promoting healthier eating and exercise.  Health has simply been approximated as a euphemism used by those pursuing society's ever-more-unrealistic expectations about weight.  No matter what they say about being healthy, most people exercise to get thinner/more cut.  If they don't get thinner, they may give up.
  • The emphasis on the visible proxy may actually encourage counterproductive behavior.  Upper class young women still smoke to stay thin (or go back when they gain post-quitting pounds); people take dangerous diet pills.  There is some evidence that weight cycling (yo-yo dieting) leads to higher mortality, either directly, or because it increases your likelihood of becoming morbidly obese.
  • The difference in observable mortality between people fifteen pounds apart (which seems to be at the edge of sustainable weight loss) is not large enough to merit either the hysterical headlines about America's weight gain, or really even dieting unless you're already afflicted with diabetes and heart disease.

I'm also convinced that obesity researchers often offer conclusions that are oddly at variance with the tone of their papers.  Take this paper on weight cycling, which summarizes much of the literature regarding weight cycling, acknowledging both papers that say it adversely impacts mortality, and papers arguing that those papers suck.  The paper says the evidence is equivocal, though it asserts that whatever effect weight cycling has on mortality probably comes because those who diet and regain end up gaining more weight than those who don't.

To me, that screams "do more research!"  But the researchers couldn't . . . quite . . . bring themselves . . .  to suggest that we might want to look into this further before continuing to recommend that people go on highly restrictive diets that they probably won't stick to.

More in general, the majority of epidemiologic studies on weight cycling and mortality have been carried out on either non-obese or only mildly obese subjects; the two studies that stratified sample by BMI showed that weight variability was more strongly related to mortality in lean than in obese subjects.4,6 Therefore, weight cycling may not have significant effects in a sample of obese subjects, about half of whom were morbidly obese, like the sample in the present study.

In conclusion, the present study shows that when examining the various components of weight cycling separately, weight loss has no adverse effects on cardiovascular risk factors that are associated with weight regain. Thus, patients should not be discouraged from trying to lose weight as for claims from the lay press,21 but the importance of avoiding weight regain should be stressed.

So we shouldn't tell people to stop dieting--we should tell them to stop regaining the weight!  Why . . . it's so simple!  How could we have missed it?

If 99% of the time the actual result of the course of action you recommend is that people diet, and then regain a bunch of weight, you need to take this into account before issuing further such recommendations.  It doesn't seem like simply proclaiming that they shouldn't go and gain the weight back again is quite enough.

After all, people who have lost a bunch of weight are presumably aware of how they did it (and if not, they need to talk to an oncologist, not an obesity researcher).  They are thus presumably also aware of what will cause them to gain it back.  Nor are they usually uninterested in staying thin.  They've usually worked very, very hard to lose all that weight, and are really quite desperate not to gain it back again.  The idea that all that was missing was a doctor telling them that no, seriously, they should really keep that weight off--an incentive obviously far more powerful than, say, the horrific way that America treats fat people--has sailed beyond arrogant into fantasyland.

This really is a pattern that you see over and over again in obesity research.  It's as if researchers are terrified to say anything that might be viewed as giving people license to get fat.  The CDC researcher who sharply revised downward the estimates of deaths from obesity, finding that overweight was actually healthier, fell all over herself proclaiming that of course, this didn't account for quality of life.  Because we know that a woman who weighs 160 pounds couldn't possibly have a decent quality of life . . . ?

This is also a partial answer to those who ask "Well, would it hurt to try?"  Of course, in their minds, none of this trying has costs, or at least, not any interesting ones.  I mean, sure, maybe it's a huge infringement of property rights, but those are sucky and archaic anyway, and no one cares about them except right wing nut jobs who don't deserve to have anything they want.  And okay, maybe people want to live in the suburbs despite ample warnings from the television that driving is making them fat, but they must not really understand this, and at any rate, once we've made them all skinny they'll be so happy with their new flat-front capri pants that they won't even notice they have a 45 minute train commute and have to go grocery shopping every day.


Would it hurt to have massively intervened in property rights, free markets, and personal liberty, and then find out that oops, it really was just cheap calories?  Shall we outlaw those too?  Millions of dollars for kale, but not one red cent for donuts?

I know, I know . . . it's for the children!  I am very fond of children.  But I do not actually think that they are some sort of master race in whose name anything at all can be justified.  And if I did, I'd be a lot more worried about, oh, abortion, than McDonalds ads.

Two final points.  Everyone likes to focus on their favorite boogeymen.  To read a left-wing blog, you'd think that about 95% of the leading cause of obesity was agribusiness, chain restaurants, and automobiles.  To read a right-wing paper, it's all the infamous lack of self-control displayed by the poor.

But in fact, most of the things effecting kids are side effects of other efforts a lot of people are rather fond of.  Processed foods and chain restaurants have exploded in the last two decades because Mom spends more time outside the home, generating more market income, and less time for home cooked meals.  Kids exercise less not because crime is higher, or even because we've become more suburban, but because they're no longer allowed to operate unsupervised until they're quite old, and Mom and Dad both work.  Schools don't have P/E because they're using the time to teach kids to read.  Maybe those were bad tradeoffs.  But they're not irrational tradeoffs, and switching them back is not costless.

The other is that while I do buy some of the arguments about hyperpalatable food like Doritos (though I personally find Doritos eminently resistable most of the time), the fact that a really attractive food combination has been cooked up by food scientists does not mean that you get some kind of free pass to deny it to everyone.  Whether a dish was dreamed up by Mario Batali or the staff at the Cheesecake Factory, preventing people from having it "for their own good" still represents an actual hedonic loss, as well as an actual loss of freedom.  You may think they have some meta-self which will thank you later, but their current self has still had both its liberty and its joy restricted.  Invoking the demon food scientists of agribusiness does not actually relieve you of the obligation to prove that intervening in the liberty of both the customers and the company is morally pressing.

To be sure, even I, the pessimistic libertarian, do not see any actual means for the government to prevent food processors from making their food taste very good. (Thank God).  I just suspect that more than one of my interlocutors is casting around for just such a means.

The government could raise the price of fat, salt, and sweeteners, processed food, and restaurant meals.  But I very much doubt that if our legislators actually enacted a food tax adequate to prevent obesity, they would get much thanks from anyone except the sort of people who ask each other, with wide eyes, if anyone else has noticed how disgustingly fat all the people are at the mall--and never eat at Cheesecake Factory.  So I think that this, too, is unlikely.

Ultimately, the answer to "what could it hurt"? is that all actions have costs, which you cannot assume away on the grounds that those costs don't interest you.  But they should interest you, because not least among those costs is the simple fact that the government cannot do everything well.  Making all sorts of changes in the name of obesity means not making others that might be more important, because we have limited political and bureaucratic bandwith.  Do you want obesity intervention, cap and trade, or health care reform?  You may not be able to have any of them.  But you probably can't have all three.  And if you did, you'd make it more likely that the government would screw all of them up.