Fat is the new climate change

Have you heard the great news? According to the latest data from the Centers for Disease Control, obesity probably only kills about 112,000 Americans every year. John Tierney and David Brooks can hardly contain themselves.

Tierney opines:

[The new research has] taken away the favorite cudgel of the scolds who used the "obesity epidemic" as an excuse to attack the flabby. The supposedly deadly consequences of fat provided the scientific rationale for the last politically correct form of prejudice.

The fatophobes are fighting on, disputing the new study and arguing that it still shows the fatal dangers of being seriously obese. But they have lost the scientific high ground. Not only do people of "normal" weight die younger than the moderately overweight, the study shows, but thin people die even younger than those of normal weight.

Not coincidentally, the food and restaurant lobby is also helping itself to the latest CDC data. Last week the industry-sponsored Center for Consumer Freedom issued a press release berating the CDC for releasing "flawed" research earlier this year (namely, the study that estimated the excess deaths at 400,000 per annum).

The Center for Consumer Freedom is a parasitic form of think tank life. Instead of producing its own trumped-up studies like the anti-global warming groups, the CCF prefers to hijack other people's work.

In the press release, the Center for Consumer Freedom basically accuses the CDC and the authors of the earlier study of propagandizing the public, if not of outright scientific malpractice. The data were there in the Center's computers all along, they press release claims. Well, yes. Of course data sets used by Flegal and her colleagues have been around for awhile. They're the three National Health and Nutrition Examination Surveys (NHANES) compiled by the Department of Health and Human Services and used for countless studies over the years. But that doesn't mean that it should have occurred to the scientists who made the earlier estimates of obesity-related mortality to use the same statistical methods as the Flegal team. There is such a thing as scientific progress. We expect later research to supersede earlier work by capitalizing on its insights and overcoming its limitations. In their article Flegal and colleagues describe how they adapted a statistical technique designed to estimate breast cancer risks to the study of obesity. I get the impression that this approach is an original contribution and not a standard technique that their CDC colleagues should have anticipated.

Sorry, guys, the but size-16 print giveth, and the size-2 print taketh away...

Flegal KM, Graubard BI, Williamson D, et al. Excess deaths associated with underweight, overweight, and obesity. JAMA.2005;293:1861-1867.

These researchers argue that earlier studies may have overestimated the impact of obesity per se because their statistics didn't fully control for the subtly confounding effects age, gender, smoking, and drinking. Flegal and her colleagues tried to overcome the limitations of previous studies by using newer survey data and more sophisticated statistical methods.

The study itself looks pretty solid to me. It's the secondary spin that's insidious. Third parties are trying to give the public a false sense of security about the obesity crisis. Being overweight is good for you, the flacks insist. Well, not exactly... (Being overweight is probably healthier than yo-yo dieting, eating disorders, or extreme bariatric surgery, but this study doesn't bear on those important issues.)

Here's the first of several catches:

The new study attributes 111,909 deaths to obesity, but then subtracts the benefits of being modestly overweight, and arrives at the 25,814 figure. [CNN]

The Center for Consumer choice has arbitrarily seized upon the 25,814 figure because it's a good stick to beat the authors of the 400,000 estimate. But why subtract the number of lives "saved" by mere overweight from the number of deaths attributable to obesity? (Flegal compared recorded-deaths-in-2000 to a what the death rate would have been in an otherwise identical parallel universe where everyone was at a "normal" weight.) It's likely that the current standards for "normal" weight are too narrow. They may even be too low for the average American. In which case we should reckon excess deaths by comparing the real world to one in which everyone is either "normal" or "slightly overweight." Even so, it wouldn't follow that obesity (as currently defined) is less common or less dangerous than we thought.

Obesity apologists are equivocating about the difference between overweight and obesity. The effects of being overweight are uncertain, but there is no doubt that obesity increases the risk of death and ill-health. Furthermore, the number of excess deaths per year is a function of the prevalence of obesity, and no one disputes that the condition is becoming increasingly common.

But does being slightly overweight actually improve health? Or is this finding some kind of artifact? The intuitive explanation is that our current height-weight tables are wrong (either for the entire population or for certain sub-groups). Maybe it's healthier to have a little extra body fat, especially late in life. Besides, some heavier people may be at lower risk because they are leaner, fitter, and more muscular than many of their lighter counterparts.

Obesity may be a big problem without necessarily being responsible for as many excess deaths as we thought. The authors found that excess risk is highest for younger obese people. But most deaths occur after age 70. So, even obesity is associated withe a large relative increase in mortality for younger people, this increase won't necessarily translate into a large absolute number of excess deaths. Whereas if weight causes even small changes in the death rate of older people, these will produce large absolute numbers of excess deaths (or lives saved). But it's also worth noting that the preventable death of a younger person probably "costs" its victim more years of life. (As Amp suggests, no death is preventable. So-called "preventable" deaths are just the ones we can postpone. Many early obesity-related deaths are eminently postponable.)

Of the 111,909 estimated excess deaths associated with obesity (BMI>30), the majority, 84,145 excess deaths, occurred in individuals younger than 70 years. In contrast, of the 33,746 estimated excess deaths associated with underweight, the majority, 26, 666 excess deaths, occurred in individuals aged 70 years and older. (Flegal K, et al., 2005)

Maybe the latest results mean that doctors should encourage older people to bulk up--but not necessarily. A "normal" weight in a person over 70 may be a sign of a more serious health problem. After a certain age, people tend to get lighter for reasons that are more sinister than simple fat loss. Weight loss in the elderly is more likely to be associated with muscle wasting, bone loss, protein/calorie malnutrition, and a host of other serious health problems that directly increase a person's risk of dying, more or less irrespective of their body fat levels. It certainly doesn't follow that it's better to be overweight throughout one's life, rather than just during the critical years. (It should be emphasized that the current study doesn't claim to establish any cause and effect relationships. It is merely a sophisticated accounting of correlations between selected variables. Controlled trails and longitudinal studies will be needed to determine the precise causal relationship between weight and mortality.)

Brooks, Tierney, and the restauranteurs also overlook the fact that being overweight is itself a risk factor for future obesity. The more people who are overweight today, the more are likely to become obese in the future. So, even if overweight isn't associated with ill health, we should still be concerned about the potential for large numbers of overweight people to become obese. And this study suggests that if obesity rates increase, excess deaths will increase as well. The more fat someone has already, the smaller their "safety margin." People tend to gain weight with age until relatively late in life. Given that so many of the Baby Boomers are already overweight, many more will surely cross the line into obesity in the next few years. Besides, there is overwhelming evidence that excess fat actually causes even more weight gain through the vicious cycle known as metabolic syndrome.

The latest data don't take into account the fact that people are getting fat much earlier in life, nor that overweight and obesity are becoming more common every year.

Children and teenagers are the fastest-growing group of obese Americans. The effects of the childhood obesity boom are already manifesting themselves in historically unprecedented rates of type 2 diabetes and high cholesterol in childhood. The current study doesn't reflect the most recent trends. The study only includes people who were at least 25 when they participated in one of the three NHANES surveys (between 1971 and 1994), so it can't give us even a cross-sectional glimpse of the effects of early obesity.

Today's obese adults are more likely to have been overweight or obese since childhood than were obese people of previous generations. We don't know what the long-term effects of earlier onset will be, but we can only assume they will be worse. How could more years of high blood pressure, high cholesterol, and diabetes be a good thing?

Even if obesity "only" kills 100,000-odd people per year, that's still a lot of preventable death. Moreover, the researchers hypothesize that excess weight is less dangerous than it used to be primarily because of better treatments for high blood pressure, high cholesterol, and other illnesses caused or exacerbated by excess body fat. All things being equal, it would be better to prevent these diseases than to maintain people on expensive and potentially dangerous drugs for life. The study didn't even attempt to measure the detrimental effects of excess weight on general health or quality of life.

Tierney and others imply that if mere overweight is good for people, then our public health programs must be misguided. But if being overweight really extends people's lives, then we should redouble our public health efforts to stop millions of overweight Americans from drifting into obesity. For these people, even a small weight gain could have dire consequences. Maybe relatively modest weight loss will also turn out to be a huge benefit for people who are already obese. Even preventing further weight gain in obese people might save many lives. If so, perhaps obesity interventions are even more cost-effective than we thought. (Strategies to reduce the health impact of obesity should include efforts to fight size discrimination, which probably has a lot to do with the negative health outcomes associated with the condition.)

Pundits and interest groups are exploiting the Flegal study as an excuse to sneer at public health iniatives, malign the CDC, and to downplay the seriousness of the obesity epidemic.

Update: I notice that Brian Leiter is as big a Tierney fan as I am.

More interesting blog-based discussion of the Flegal from Alas, a Blog, Left Oblique, and Kevin Drum, and Jay Sennett.

Comments

[MoXmas]

A minor question out of that long post, but: what's the problem with yo-yo dieting? I have seen a couple of nutritionists say that the problem with yo-yo is just the "put weight back on" part. But that rapidly losing weight and the putting it back on is no worse than having that weight on in the first place.

Just curious

[Bruce the Canuck]

Great post. It seems that they're confounding the results for different age groups to take their favoured conclusion from the study.

And then, there's the elephant in the room, diabetes. What would the death rates be without insulin, blood pressure pills, and other expensive medical care? Do we want to be a whole society of people stuck on some drug or other just to live?

[Lindsay Beyerstein]

Weight-cycling is bad because people often gain back more weight than they initially lost and regain it in a less healthy form than they originally had. Sometimes weight cycling exacerbates atherosclerosis. Often people lose muscle when they diet and regain fat weight without replacing their lean body mass.

When people lose weight they tend to lose fat from under the skin and gain it back in the abdominal cavity, which a statistically riskier place to carry it.

I think weight cycling can also contribute to gallstones and other problems, too.

The physical and emotional strains of the whole process are can contribute to depression, eating disorders, and general ill health.

[Treban]

"What's the problem with yo yo dieting?"

Rapid weight loss, especialy if metabolic stimulants are used is also one hell of a shock to the heart. Combine that with obesity providing increased wear on the heart, it can be a serious if not fatal situation. Not to mention most metabolic stimulants are also quite addictive.

Trying to claim obesity is not a danger will just cause people to believe that it's ok to get fat. It's not. Just because it's also not healthy to be to skinny and malnurised dosn't mean the other end of the spectrum is any better. Either extreme is dangerous, just like most extremes are dangerous.

[Njorl]

If being a little overweight has the highest life expectancy, shouldn't that be considered proper weight? I suspect that the definitions of proper weight are wrong. I had my body-fat content measured when I joined a gym, did some math and saw that my doctor had recommended I lose all of my body-fat and then some. That would, of course, kill me.

[Alon Levy]

If 110,000 excess deaths per year are no big deal for Brooks, why does he worry so much about terrorism? If 110,000 dead Americans per year are nothing, then so are 3,000 dead Americans.

[arrega noe]

Lordy - these kinds of studies are like jerkoff material for the Brooks and Stossels of the world. They can use them again and again to reach orgasmic heights of illusory triumph over their presumed enemies.

As soon as this latest fat one came out, though i feared for those who would use it to stop doing the necessary work of getting and staying fit, the fear of the pundits was more daunting. I could see their gloating and bogus identification scheme immediately: "Seeeee! everything "we" do in America is right! Everything "they" tell us is wrong! Pundits playing podunk is always a sure sign that the wheels will soon be falling of the cart.

What amuses me the most about this latest attack of the good ol' folks against the evil Leftists science brigades is that now we at least have a clear presentation of the two front culture war-

the theater of pleasure:
Hate the Left, they are hedonistic hooligans who use drugs and buttsexx to break up your family!

the theater of pain:
Hate the Left, they are cold and heartless killjoys who use "science" and "experts" to question the sacred habitus of "the people!"

Funny too how these pundits love to claim something akin to "see, this shows experts don't know anything" as they pose as pseudo experts who now _really_ do know everything.

Also interesting that when the argument turns to things economic, where the "experts" have also come to a pretty clear consensus, though somewhat at odds with the attitudes of the masses (i.e. neo-liberal austerity - "free trade" etc vs. worker protection, single-payer healthcare, environmental protection), then suddenly the experts _do_ happen to know best.

what a gig.

[Barbara]

The two caveats in this study have been completely emptied of content. The first is that "obesity" is a clear risk -- and it is obesity that is clearly on the rise, among children in particular. So if 8% of the adult (over 25) population were affected as of even a couple of years ago, that portends some pretty scary consequences over the next 20 years. 8% is a huge number of people -- think about it if 8% of the adult population were HIV+ or had some other chronic disease. The number is only going higher and it is going higher at a younger age.

The second, as Lindsey pointed out, is the likelihood that health effects of "moderately excess" weight are being blunted by better drugs and treatment. Now, this is good, but it is certainly not optimal, particularly given the expense of many of those drugs.

On the other hand, I do think that scientists have left themselves somewhat exposed to this backlash, because of the tendency (or need) to overstate a problem in order to get attention and funding. This, unfortunately, has come about through zealous and welcome advocacy groups, such as those seeking to eradicate breast cancer -- the dreaded statistic 1/9 is used without acknowledging how it was derived, and that, when viewed in context, can be supported only as a scare tactic.

[stand_up_philosopher]

The intuitive explanation is that our current height-weight tables are wrong (either for the entire population or for certain sub-groups). Maybe it's healthier to have a little extra body fat, especially late in life. Some of the heavier people may be at lower risk because they are leaner, fitter, and more muscular than many of their lighter counterparts.

I haven't read this study, but if they are only using height-weight tables and not controlling for muscle vs fat, then being "overweight" might be the result of more muscle and not too much fat, and being "underweight" might be muscular atrophy. The real problem would be hypokinesis (lack of working out) which doesn't allow proper body composition (muscle / fat ratio), which cannot be measured by a simple height / weight ratio. Of course, not working out can't simply be traced back to laziness, but has all sorts of factors (access to facilities, encouragement, technique, etc.).

[Lindsay Beyerstein]

SUP, I agree. There's a pretty good correlation between height/weight and body fat, but it's certainly not perfect. BMI recommendations are predicated on the assumption that you have an average body composition, i.e. a typical ratio of muscle to fat. If you're more (or less) muscular than average the recommended BMI range many not be appropriate.

BMI tables are just statistical guidelines for populations. I wish doctors were more emphatic about this. Any given person can be fit and healthy but lie outside these general guidelines. If someone weighs more than the BMI tables predict, that's a datum, not proof of ill-health. It's the physician's job to gather other evidence about that patient's health like exercise history, blood pressure, nutritional information, and so on. Statistical outliers are what makes life interesting.

[Cookie]

The height/weight tables are a joke. I'm virtually anorexic at ten-fifteen pounds over my supposed ideal weight - the high end, I might add. The tables don't take into account bone density, muscle and other factors. I mean, not to be crude, but I'm fairly busty and I'm certain that alone tacks on a good 10 pounds. I also have very dense bones, and might be a far cry from the female Chas Atlas, but could easily rabbitkick Atlas to the next planetary zone, thanks to muscularity.

In general, I think Americans are completely irrational about weight and nutrition and whatnot. Either they're defending their obesity or they're defending their anorexia or their addiction to trans-fats and crap food or they're taking pills to cover the effects or they're dashing from fad diet to fad diet or whatever.

And that isn't to defend the obese, not by any means. But if we didn't get so crazy over the whole issue, maybe people wuld simply settle into eating a decent diet and walking everywhere (or whatever), instead of depending on pills and gastric bypass and WHATever.

Not to mention the whole trans-fat thing. Which is a whole nother can of worms.

[Mandos]

I'm actually somewhat overweight, but aside from this past couple of weeks (and maybe for the next few---busybusy, but of course not busy enough to avoid commenting on blogs) I usually eat pretty healthy and exercise regularly, and I don't use a car to get around for the most part.

So I have some excess fat. And it would be nice to lose it. I like food too much. But I think if I at least live healthy, that's 3/4ths the battle.

[janet]

The problem both with this study and other studies on health consequences of weight are that there are just too many factors that can't be controlled for. BMI is too blunt an instrument to be useful in this kind of analysis -- I wonder why the CDC bothers with it.

BTW, Lindsay -- It's either "[the] metabolic syndrome," or "syndrome X," not "metabolic syndrome X." I believe the term "syndrome X" is out of fashion at this point.

[Lindsay Beyerstein]

BTW, Lindsay -- It's either "[the] metabolic syndrome," or "syndrome X," not "metabolic syndrome X." I believe the term "syndrome X" is out of fashion at this point.

Thanks, Janet. I fixed the post. I had the "or" construction in the first draft, but I changed it when I found out that the National Library of Medicine uses http://www.nlm.nih.gov/medlineplus/metabolicsyndromex.html>metabolic syndrome X as a PubMed search term.

But plain old "metabolic syndrome" sounds better and fits better with clinical usage.

I think that these BMI studies have their place. It's a tradeoff between sample size, construct validity, and data quality. Researchers can get lots of data at low cost with BMI because height and weight can be measured so easily and precisely.

Body composition is much more expensive and time consuming to measure. It's difficult to get an precise, accurate measure of body fat without underwater weighing. All the other methods use regression equations to map the surrogate measure onto densitometry studies. For example, the skin fold thickness measures were standardized by doing skin folds and underwater weighing on a group of subjects and seeing how well the indirect measure of fatness correlated with the direct measure of body fat. Add to that the fact that the investigator has to be pretty skilled at whatever anthropometric measure she chooses in order to get reliable readings at all.

The whole picture won't come together unless we can use all the different experimental methods and cross check them against each other. We also need more longitudinal data.

[janet]

I like "metabolic syndrome" better, too. "Syndrome X" could be anything, and besides, it reminds me of Speed Racer.

As I was thinking about the rest of your reply, it occurred to me that BMI studies might be less misleading if they renamed the categories, because "obese," "overweight," etc. are the same words we use in conversation, and the subjective meanings each of us has for these words don't necessarily track with the technically defined ranges. I think that's where part of the confusion comes from, especially with know-nothings like Brooks and Tierney taking an already simplified and misleading piece of reporting and spinning it out of recognition.

[Susan Nunes]

A certain body type is NOT a disease. That's what the medical establishment and their allies in the diet industry CAN'T get through their heads.

THAT'S why it is difficult if not impossible to lose weight and keep it off. It's going against nature.

It's time for people to recognize the anti-fat war isn't so much based on health concerns as it is on PREJUDICE.

[Alon Levy]

Obesity is a disease, Susan, despite what you say. It increases the risk of diseases such as diabetes. That it's hard to quit doesn't mean it's not bad for people; it's difficult to quit heroin, too, but heroin addiction is not a body type.

[Ampersand]

Obesity is a disease, Susan, despite what you say. It increases the risk of diseases such as diabetes.

I don't think the logic of this argument holds much water. Being black increases the risk of diseases such as Sickle Cell Anaemia. Is Blackness therefore a disease?

[Alon Levy]

First, blackness at the same time increases resistance to sunburn, whereas obesity has no similar positive effects. Second, blackness is not something you get from eating junk food. Third, whereas blackness is purely genetic, obesity is not, judging by how its prevalence has risen so considerably in the United States in the last few decades. There probably are some people who are genetically obese, but many others are obese purely because of lifestyle choice.

[Mary]

Sorry, guys, the but size-16 print giveth, and the size-2 print taketh away...

Just lovely. Also making me angry alomst beyond words is the idea that this study will suddenly make people think it is "okay" to be fat. Oh right, like even if 1,000 studies found no health risks from obesity, we wouldn't still get abuse from thin folks who hate the way we look and feel compelled to tell us at every opportunity.

[Lindsay Beyerstein]

Mary, I don't understand what you're so upset about. I'm not making any moral judgments about size or weight. It was wrong when the tobacco companies said "It's okay to smoke." Morally, yes, it's okay to smoke.* Medically, it's not as healthy as not smoking. Everyone has ther right to take whatever risks they want with their own body and to make their own cost-benefit decisions about quality vs quantity of life.

Who said anything about moral superiority? Weight has a huge genetic and involuntary environmental component, so there's not much to feel superior or inferior about. Yes, people who have a healthy lifestyle can be proud of that, but as we've discussed at length on this thread, you can't judge by BMI whether someone is exercising self-discipline. Furthermore, there's little intrinsic moral value in placing an extremely high priority on health. Total disregard for one's health would almost certainly be irrational, and maybe even unethical. But beyond that, health nuts aren't necessarily better people than epicureans.

(I don't buy those guilt trips about driving other people's insurance up, for smoking, diet, inactivity, or any other health risk. That's why we need a sane national health plan that doesn't pit everyone against everyone else, by slicing and dicing people into sub-sub-risk groups.)

*Assuming you don't do so among innocent bystanders in close quarters.

[Lawrence Krubner]

"Mary, I don't understand what you're so upset about. I'm not making any moral judgments about size or weight."

When discussing politics, I've learned, people mostly belong to one of two camps. Either they view the subject under discussion as a moral issue or they view it as a matter of public policy. I find the two groups have trouble talking to one another, or even understanding one another. Both viewpoints are learned habits of thought, but the "subject is a moral issue" viewpoint is often learned at home from one's folks whereas the "subject is a public policy issue" is often learned at school. There the public-policy-viewpoint people have an easier time understanding the subject-is-moral-issue crowd than vice versa.

I've offended friends in the past by making remarks like "Per capita consumption of sugar has increased 300% since 1945". All I meant was to suggest that perhaps America needed a policy change in regards to health education, but they think I'm accussing them of a moral failure because they eat sugar. Such accussations are stunning, till you get used to them.

[Mary]

Sorry, guys, the but size-16 print giveth, and the size-2 print taketh away...

Oh, was that like a COMPLIMENT to Size 16 wearers that I was just too FATHEADED to absorb? Lindsay, you pretent to be all objective and intellectual but comments like that are pure evil. Yes, your blog photo shows you to be quite thin, but it also make syou look like you have 1) had collagen injections or 2) have a honking bad cold sore. Shall we discuss the health risks of plastic surger or herpes simplex?

There are a lot of deleterious ways a person can handle stress:
- physical or emotional abuse of others (fat people being an obvious target, especially those wretched size 16s..)
- gambling
- shop lifting
- reckless (but not wreckless) driving
- drinking
- drugs
- overspending/compulsive shopping
etc., etc. Compared to all of these, overeating is the most considerate to those around them. Unless an overeating person is literally stealing food from another, it is the one way of being self-destructive that DOESN't harm others. Fat people tend to be the nicest people, unless they have been abused too much like pretend intellectuals like you.

[BFB fan]

Right on. Amp was too nice to her.

[Quisp]

Must. Comment. Can't. Look. Away.

Maybe it's just me, Mary, but I thought the size-16/size-2 print was a reference to font size, not dress size. In other words, read the fine print.

Also, as Mary points out, compulsive overeating is a mental illness that requires treatment. I'm not sure that I agree with Mary that it's the most benign of all the compulsions she lists. In fact, I think it overlaps with some of them.

And as to the assertion that "fat people tend to be the nicest people," I am compelled to (only half-facetiously) counter with, that's exactly what they would have you believe. Actually, an informal and utterly unscientific study of my address book reveals no correlation between fatness and niceness; however, the fat rich demo are mostly mean motherfuckers whereas the fat poor mostly act really nice. Just sampling for "mean"/"not nice" I see no pattern re fatness. However, among the people in my address book, there is a very strong link between those who are fat and those who eat the most crap and don't exercise. Your results may vary.

This makes me wonder though. They say there's a link between depression and obesity. And it's also said that depression is anger repressed. This suggests that in fact fat people are angrier than the norm, not the opposite, per Mary's Theorem.

Lindsay -- I will repeat what I said elsewhere about your Cash-sneer photo. It appears to make people frothy insane. (I liked my Frege and muses idea, which you politely ignored. Insert smiley face.)