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Obesity Apocalypse

[ 72 ] August 4, 2008 |

Even by the remarkably mendacious standards of the “obesity” racket some of the claims in this story are beyond belief.

The most laughable is the idea that by 2048 everybody in the US will be “overweight” or “obese.” This result was derived via statistical extrapolation, the crack cocaine of social science analysis (by similar methods one could prove that within a few generations Olympic sprinters will be running at speeds that will hurl them into low Earth orbit and everyone in America will have a plasma TV seventeen miles wide).

In fact there has been no weight gain at all over the past 30 years in the thinnest quartile of the population — whatever (poorly understood) factors have caused Americans to weigh more on average now than they did in the 1970s have had very different impacts across the weight spectrum: thin people have gained no weight, people in the middle weigh 10-15 pounds than they did 30 years ago, while the fattest people have gained a lot of weight, which is exactly what one would expect. Furthermore, as even this story manages to note, there’s quite a bit of evidence that the trend toward weight gain in the populace in the 1980s and 1990s seems to have plateaued.

But this is a side point. The most significant and symptomatic aspect of this story is it’s completely uncritical attitude toward the current definitions of “overweight” and “obesity.” Those definitons are BMIs of 25-29.9 and 30+ respectively. (You can look up your own BMI here, and I encourage you to do so).

I really can’t emphasize enough how utterly without scientific foundation these definitions are. This can be shown in a hundred ways, but here’s one particularly striking illustration.

The best epidemiological data on the U.S. population is the CDC’s National Health and Nutrition Examination Survey (NHANES). This is universally recognized as the gold standard for such surveys, in particular because it’s a nationally representative sample that directly measures its participants. NHANES has been ongoing since the 1960s; the most recent data that allows for significant followup is from NHANES III, which was assembled in 1988-1994.

Now if we’re facing an “apocalypse” because of “overweight” and “obesity,” we should see evidence of this in, at the very minimum, increased relative risk of mortality among people in these categories. Here’s the relevant data from NHANES III on mortality risk. The following statistics use the mortality risk found among supposedly “normal weight” (sic) people (BMI 18.5-24.9) as the referent group. In other words, the mortality risk for this group sets the baseline for comparison to other groups in terms of their mortality risk. A group that has a higher mortality risk than the referent group will have excess deaths over the baseline risk. A group that has a lower mortality risk will have fewer deaths than would be seen in the group if it had the same mortality risk as the referent group of “normal weight” people.

Most recent excess deaths estimates from NHANES III:
Underweight: 38,456
Normal weight: 0
Overweight: -99,980
Obesity Grade I: -13,865
Obesity Grade II and III: 57,515

Underweight less than 18.5 BMI, normal weight 18.5-24.9, overweight 25-29.9, Obesity Grade I 30-34.9, Obesity Grade II and III 35+ What these numbers mean: In the US population at present, we are seeing about 100,000 fewer deaths per year among “overweight” people than we would if “overweight” people had the same mortality risk as “normal weight” people. Note that the majority of people in the US who according to the government’s current classifications weigh too much are in this group. The “overweight” category is to the obesity panic what marijuana use is to the drug war: stories about an “epidemic” of fatness depend crucially on classifying the 35% of the population that’s “overweight” as being at some sort of increased health risk. This is simply false, and is known to be false by the researchers who are quoted in stories like the one linked above.

But the situation is much more egregious than even this suggests. Note that the NHANES III data reveals that most people who are classified as obese have a lower mortality risk than so-called normal weight people. About two-thirds of “obese” Americans have a BMI of between 30-34.9, and currently we’re seeing about 14,000 fewer deaths per year in this group than would be expected if the group’s mortality risk was the same as that of “normal weight” individuals.

Only when one gets to roughly the fattest 10% of the population does the NHANES III data begin to find a relative mortality risk higher than that found among the supposedly “normal weight.” And even here, the relative mortality risk results in about three times fewer deaths per capita than observed among the “underweight” (there are approximately four times as many people with BMIs 35+ than there are people with BMIs below 18.5).

In short, it’s difficult to convey the utter intellectual bankruptcy of the standard discourse surrounding weight and health in this culture.

Update addressing a couple of common themes in these sorts of discussions:

(1) I don’t think that the higher mortality rate among “normal” (sic) or “optimal” (sic) weight people provides any real evidence that someone with a BMI in that range should try to gain weight. The bogus idea here is that a narrow range of weight is optimal for all people. In fact the differences in mortality across an extremely broad range (roughly BMIs from the high teens to the mid-30s) are statistically trivial, and represent the kinds of differences in relative risk that nobody would ever pay attention to if not for cultural considerations that make body mass a subject of great symbolic (though not medical) importance.

(2) It really is astonishing how ready people are to accept the most dubious evidence for the proposition that everybody should try to be thin, while engaging in sophisticated arguments about why evidence to the contrary can be explained away. That this blatantly inconsistent attitude is characterized as the essence of science is also rather remarkable.

Comments (72)

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  1. Gander says:

    Marc wrote:
    For example, any weight vs. mortality study has to account for the severe weight loss that accompanies many terminal illnesses. Not doing so is a legalese trick – failing to mention an inconvenient datum that undercuts your case. As a scientist this makes me simply bristle. That’s just not how the game is played.
    Similarly, any weight vs. mortality study has to account for the weight gain side-effect that accompanies many conditions with a high risk of mortality. Not doing so is a legalese trick – failing to mention an inconvenient datum that undercuts your case. As a scientist this makes me bristle, especially when compared to the argument for taking into account weight loss that accompanies many terminal illnesses.

  2. Marc says:

    You’ve given me a partial answer Paul – again, in a deliberately antagonistic and adversarial legal approach. If I enter the study with average weight, get sick and emaciated, and then die – do I count as a “thin death” if it happens more than 3 years into the program? If so, why does this tell me anything? Why are you presenting absolute numbers instead of rates per 100,000 per year? Have you controlled for age?
    I count a claim like this blog post, with important confounding information *not* prominently displayed or discussed, as a piece of advocacy rather than a piece of research. That is my problem sannanina.
    And there is another reason why this approach makes me extremely uncomfortable. I see precisely the same logic from creationists and global warming deniers. Contempt for expert opinion (those “scientists” say these things and didn’t even do obvious comparison X”! They don’t even know that water vapor is the most common greenhouse gas and the sun controls climate!). I see an awful lot of emotionalism and hostility to fair questions in the comments here, right down to the “scientists only report things that I don’t like because they are being paid off.” That’s a standard global warming denialist claim. When a blog post author challenges someone in the comments to come up with data – that means that they do not themselves know the answer. If someone asks me a factual claim in my field I can tell them (verbally) where it comes from or I can do the research (in writing) and come up with backup. Otherwise it simply comes across as “oh yea? You can’t prove me wrong. I win! I win!”
    And that is too bad, because there is an interesting scientific question about what, say, the health risks of being overweight (as opposed to obese) actually are – if there are any.

  3. aimai says:

    Well, I’ve got a lot of emotional feelings about this issue since I’m classified as “obese” and struggle with these issues daily. However, that being said, I really resent the implication that the entire discussion is tinged with “global warming style” denialism. On the contrary, we are arguing about a host of issues on which the science is still out, and on a set of questions about the remedies for the condition on which the science is, likewise, still out.
    Look, no one would deny that calories are freely available in this society and that time/space/safety for expending calories are, in fact, not freely available. Also, people exist in families and communities that make acting as sole custodians of their bodies complicated events. A science that focuses on individuals and individual outcomes when commensality and life itself is lived in groups is, to my mind, going to fail at finding proper interventions. That’s my scientific opinion qua anthropologist and not the result of some kind of blind spot a la global warming denialist.
    Second, I’d like to point out that all this talk about the mortality and morbidity associated with fat assumes that there is an ideal type body that lives forever with no health problems that we should all strive for. That’s a religious article of faith for some doctors and many laypeople, but its no more true than any other religious belief. The human body is capable of many things but eternal life at optimum weight is only one of them. Getting out, doing shit, having children, making art, making love, living well are also goals that individuals may have. Fat interferes with these goals only to a very small degree–the continued drumbeat of accusations, humiliations, and public health hysteria over fat interferes much, much, more.
    aimai

  4. Paul Campos says:

    “There is a strong international consensus among scientists that OVERWEIGHT and obesity are significant contributors to morbidity and mortality.” (my emphasis)
    Walter Willett and Meir Stampfer, Harvard School of Public Health.
    If by “scientists” they mean “people whose entire careers are structured around the claim that not being thin is a major health risk” then this claim is probably true.
    By contrast, a lot of other people, including a lot of scientists and social scientists in the academy, think the claim that overweight is a significant contributor to ill health and premature mortality is completely bogus, and that a similar claim for obesity is greatly exaggerated.
    You can of course dismiss this sort of dissent as anti-scientific denialism, but in my view precisely what’s at issue here is who is in denial.
    As for the substantive point about weight loss, NHANES uses BMI at entry into the participant pool as the measure for correlation between BMI and mortality risk. The study controls for age. The excess death figures reflect the varying relative risk as applied to cohorts of different sizes.
    As others in this thread have pointed out epidemiology is a crude and inexact science, in which many of the relevant variables can never be adequately controlled for. One of the few things we know for certain is that there is no excess mortality or overall morbidity associated with the so-called overweight category.

  5. Hogan says:

    I count a claim like this blog post, with important confounding information *not* prominently displayed or discussed, as a piece of advocacy rather than a piece of research.
    OK, let me ask you this: So fucking what?

  6. Marc says:

    Epidemiology is a blunt tool. It’s extremely difficult to use rigor to identify all but the most obvious risks. We absolutely agree Paul; I’d have very similar attitudes and questions directed at, say, the authors of the paper that you are critiquing.
    You don’t fix that in the mind of the public with tit-for-tat. You pick an example, like the one that you present, and then use it as a teaching tool. You add in information about how age impacts things; about different categories of illness; and so on. Or you stop with the critique of the silly extrapolation in the paper. You don’t counter one misleading example with another. You address up front the thresholds above which weight really is an issue – instead of implying that it never is. I am completely prepared to believe that the risks associated with “overweight” are overestimated or uncertain – or maybe they are not. If you make the same claim about obesity then you lose me.
    More to the point, if you are interested in policy then you have to begin by understanding what problem, if any, that you have. If it’s no big health issue for people to weigh an “extra” 50 pounds, why bother talking about exercise? Why bother looking at the mix of food we eat?
    By contrast, if there are health consequences for weight above some optimal range then there is a good medical reason to rethink how we’re doing things. I share skepticism about, say, diets – but we could clearly make social choices that promote healthier exercise and eating habits that would pay off in a generation down the road. You’d only go for shorter time scale changes for high risks (like smoking.) The threshold for that in terms of weight is much higher than the threshold where there is excess risk.

  7. Hogan says:

    If it’s no big health issue for people to weigh an “extra” 50 pounds, why bother talking about exercise? Why bother looking at the mix of food we eat?
    Perhaps because those are health issues completely independent of their effect on weight? And because focusing on weight as The Big Bad actually diverts attention away from those issues?

  8. peggynature says:

    “there are approximately four times as many people with BMIs 35+ than there are people with BMIs below 18.5″
    And I think that, right there, might say something about what the human body is even willing to tolerate.

  9. LouiseL says:

    “By contrast, if there are health consequences for weight above some optimal range then there is a good medical reason to rethink how we’re doing things. I share skepticism about, say, diets – but we could clearly make social choices that promote healthier exercise and eating habits that would pay off in a generation down the road. You’d only go for shorter time scale changes for high risks (like smoking.) The threshold for that in terms of weight is much higher than the threshold where there is excess risk.”
    Ah, lifestyle changes. I think most people are all for eating an enjoyable, balanced diet, and getting physical activity in reasonable amounts. The thing is that doing this does not in fact make fat people much thinner, if at all. It does, however, contribute positively to overall health. We MUST take weight out of the equation for this idea to work as a health aim or policy. If weight is inlcuded in measures of success in programs that encourage “healthy lifestyles”, they will always, always fail.
    Yes, probably there is a small percentage of the “obese” population that has higher body weight because they generally eat (for whatever reason, and there are many) calorie-dense foods and don’t get much exercise. But studies on food intake and activity consistently show that fat and thin people don’t actually eat differently, often much to the surprise of the researchers. There are plenty of thin people who eat loads of “junk” food and never exercise yet remain thin, thanks to their genetic makeup. Likewise, there are plenty of fat people who have “healthy lifestyles” and remain fat.
    So: let’s help people of all income brackets have decent access to a range of affordable, fresh foods; safe neighbourhoods in which to exercise, community gyms/activities; full access to preventative and general health care; and relieve the stigma and discrimination that causes negative health effects through stress – racial, gender, weight, etc. Those are the things that will have positive benefits for individuals and communities, not this idiotic fixation on weight and BMI. Do those things for health’s own sake, not to make people thinner. And don’t make Health some kind of glorious grail that will make you live forever, either.

  10. I don’t know about looking at fat people causing ulcers. I do know that when fat people tell me stories of how they’ve been treated, I feel like having a heart attack myself.

  11. Kmtberry says:

    Weel, Paul, I think your post is GREAT! I have a question/thought: I never seem to see AGE figured into the head-scratching about “Americans weigh more since the seventies”. IIRC, the median age of America was something like 26 in 1975 (? I am just remembering here, folks, I could be WRONG!) and now it is something like 43?
    I don’t know about the REST of you guys, but I put on some weight between ages 26 and 43. Just sayin.
    Of course, such an OBVIOUS thing may be accounted for by the statiticians. Unles of course they are mainly trying to make the numbers say that we all need to lose weight and ask me how!

  12. AmandaP says:

    Yes, probably there is a small percentage of the “obese” population that has higher body weight because they generally eat (for whatever reason, and there are many) calorie-dense foods and don’t get much exercise. But studies on food intake and activity consistently show that fat and thin people don’t actually eat differently
    I see this argument a lot on the internet, but have not been able to find more than a few outdated studies based on people’s self-reported intakes. I’m curious if there are a lot of studies that show this. As far as I understood, metabolism wasn’t that highly variable in people.

  13. Karen says:

    The issues regarding weight loss, smoking, illness and early deaths affecting the results were pretty extensively addressed in a publication (Flegal et al Impact of smoking and preexisting illness on estimates of the fractions of deaths associated with nderweight, overweight, and obesity in the US population.Am J Epidemiol. 2007 Oct 15;166(8):975-82. }. This shows that these factors really didn’t affect the results.

  14. Karen says:

    Anonymous wrote “A decreased total number of deaths in a particular class doesn’t mean a decreased risk of death if that particular class is smaller by the same percentage. That is, if the overweight class is, say, 40% of the population, and risk of death were equal, you’d expect 40% of the deaths to be in the overweight class and 60% in the normal/underweights. That would result in a substantial apparent decrease in absolute numbers, but it wouldn’t mean any decrease in risk.”
    This is a misunderstanding of what is being calculated in the Flegal paper and the two earlier papers by Allison and Mokdad. These papers are not calculating the total numbers of deaths in a weight class. They are calculated the total numbers of deaths in a weight class ABOVE AND BEYOND the expected numbers. That’s what makes them excess. For instance if 40% of the population are obese and 50% of the deaths are of obese people, then 10% of the total deaths in that population are extra deaths associated with obesity. These kinds of calculations are called attributable fractions. They are basically combining prevalence estimates with relative risks to get absolute numbers. If there is some weight category with a huge relative risk, like 10, but there are only three people in the US who fall into that category, then its overall absolute impact is smaller than a category with relative risk of 1.01 that half the population falls into, even though its relative risk is higher.

  15. Karen says:

    Anonymous wrote “A decreased total number of deaths in a particular class doesn’t mean a decreased risk of death if that particular class is smaller by the same percentage. That is, if the overweight class is, say, 40% of the population, and risk of death were equal, you’d expect 40% of the deaths to be in the overweight class and 60% in the normal/underweights. That would result in a substantial apparent decrease in absolute numbers, but it wouldn’t mean any decrease in risk.”
    This is a misunderstanding of what is being calculated in the Flegal paper and the two earlier papers by Allison and Mokdad. These papers are not calculating the total numbers of deaths in a weight class. They are calculated the total numbers of deaths in a weight class ABOVE AND BEYOND the expected numbers. That’s what makes them excess. For instance if 40% of the population are obese and 50% of the deaths are of obese people, then 10% of the total deaths in that population are extra deaths associated with obesity. These kinds of calculations are called attributable fractions. They are basically combining prevalence estimates with relative risks to get absolute numbers. If there is some weight category with a huge relative risk, like 10, but there are only three people in the US who fall into that category, then its overall absolute impact is smaller than a category with relative risk of 1.01 that half the population falls into, even though its relative risk is higher.

  16. There seems to be a bit of a problem with the BMI, at 5-9, 145 I am at 21.5 – smack in the middle of normal. I find that odd, I have a specific gravity slightly in excess of 1.0 since I sink in water, I cannot float, I can tread water.
    I am small boned and very muscular a different build than most, which this particular index takes no note of.

  17. francine says:

    For many people obesity is unwilling — they have tried and tried and any success is followed by a rebound; it is frustrating. I was lucky. I found out it was yeast and lost 186 pounds 7 years ago. Anyone obese should consider the likelihood that they have Candida yeast – all the information is available in my book and on my website BeautyAndTheYeastBeast.com as well as the naturopathi antifungal my lab developed. You don’t have to get skinny – you do need to mind your health.

  18. Anonymous says:

    Marc asked:”If I enter the study with average weight, get sick and emaciated, and then die – do I count as a “thin death” if it happens more than 3 years into the program?”
    No, in these type of studies, weight changes after the beginning of the study don’t enter into the calculations. If you start out with a BMI of 50 you will be counted as a “fat death” even if you later lose 200 lbs. If you start out with a BMI of 18, you will be counted as a “thin death” even if you later gain 200 lbs.

  19. Dr.Chester Prof. Chatwin says:

    Obesity is one health condition that has attained serious proportion all over the world and especially the US. In this country obesity has infact been declared an epidemic. ItâAos not unnatural therefore that the government and the other related organizations are making vigorous efforts to educate people on the same. The weight loss drugs are also being targeted at the population of this country. US being the richest nation with the highest per capita income these drugs have found buyers in this country. http://www.phentermine-effects.com.

  20. It’s posts like these that just might help set us perfectly healthy fat people free of the crushing prejudice and nonsense we have to put up with on a daily, miserable basis.
    What kills me is all of the *living* proof that fat people can be perfectly healthy and thin people can be very unhealthy. How can people be so blind? I’m fat and pregnant. My BMI is 39.1 **GASP!** I’ve been scare mongered half to death for six months of my PERFECTLY HEALTHY pregnancy. Instead of having a peaceful, joyful pregnancy I’ve been terrified out of my mind that at any moment I’m going to keel over and die of FATNESS or I’m going to lose my baby.
    Not only that, but the hostility I’ve had to face! And for what?? I’m healthy! Although perfectly healthy I’ve been discriminated against from the first maternity appointment and treated like a diseased individual. I’ve had the label, “High Risk” slapped onto me because of my “increased risk” of gestational diabetes and high blood pressure… even though I don’t have any of these … and told I have to be shipped away to give birth at a “high risk” hospital. (Not only that but I’m expected to go live in said hospital starting in my 38th week.) Even though I’m perfectly healthy I’m being PUNISHED just because I’m fat. I’m being culled from the herd because I’m not “good enough” to give birth with the thin ladies. This obesity hatred/fear/prejudice is getting out of hand in our society! It’s setting up elitist “no fatties allowed” situations even in maternity wards! I’m fit, I have a BP of 110/60, no sugar or protein in my urine… and what do I get for my good health? Discrimination, prejudice, and a totally miserable pregnancy. And I still have three months to go! What a way to be a first-time mother. **Grumble**

  21. Kaleberg says:

    The Flegal paper is at http://www.cdc.gov/nchs/products/pubs/pubd/hestats/excess_deaths/excess_deaths.htm
    The study looks pretty good. Flegal breaks out people over and under 70, controls for self and doctor report health status and so on. It sure looks like that having a normal BMI is associated with an increased probability of death. Interestingly, people who thought they were healthy were less likely to die than people whom doctors thought were healthy. You can find all sorts of weird things data mining. It’s worth reading.
    As for the alcohol thing, I mainly gather it is a wine related thing. The French drink a lot of wine and have a low death rate from heart disease. The Italians drink a lot of wine, but not as much as the French, and they have a low rate of heart disease, though not as low as that for the French. If you plot wine, not alcohol, consumption, more wine means less death from heart disease. There is an increase in liver disease, but liver disease is so much rarer than heart disease that it pays to encourage wine.
    As for mechanisms, well it looks like scientists have their work cut out for them. You can predict the phases of the moon just fine without the theory of gravity, but any theory of gravity has to predict the phases of the moon properly. If we find mechanisms for wine or weight shortening life spans, we also have to find confounding factors.

  22. [...] fat and diabetic by the year 2030, using about the same methodology which “projects,” in the deathless words of Paul Campos, “that within a few generations Olympic sprinters will be running at speeds that will hurl [...]

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