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French Scientists Link Higher BMI with Lower IQ 728

Xemu writes "French scientists have linked obesity to lower IQ reports the Telegraph. In a new five-year study of more than 2,200 adults, people with a low body mass index (BMI) could recall 30% more words in a vocabulary test than those who were obese. The fatter subjects also showed a higher rate of cognitive decline when they were retested five years later. In the United States, 30% of the population is obese according to OECD. That's the highest rate of obesity anywhere. Do these high obesity rates affect the average IQ of the population?" (Of course, this sidesteps discussion of whether IQ tests measure anything significant at all.)
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French Scientists Link Higher BMI with Lower IQ

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  • BMI is not accurate (Score:5, Interesting)

    by Harmonious Botch ( 921977 ) * on Sunday October 15, 2006 @05:24PM (#16446169) Homepage Journal
    The Body Mass Index is not accurate. It is basically mass vs height, and makes no distinction between fat and muscle, both of which increase mass measurements.

    During the rainy season, I don't exersize, so I lose muscle mass and get skinny, and I look - pardon me for saying it - like a geek. And my BMI is normal ( and allegedly healthy ). But during the other ten months, I am more muscular ( and probably a lot healthier ) and yet I am technically obese, according to the BMI.

    Do I feel smarter? Heck, I'm a slashdotter - I think I'm smart all the time.
    • You are a single data point.

      Yes, BMI makes no fat/muscle distinction and recognizes a body builder as "obese." (BTW, how much weight do you gain to go from "normal" to "obese"? Because there is an "overweight" level between, under 30 BMI IIRC).

      But I think it is safe to say, that the overall trend is that people with a higher BMI have a higher fat %.

      I know, from personal experience, when I'm significantly thinner, my brain is less occupied with food. I feel mentally and physically faster. Of course, more
      • by sumdumass ( 711423 ) on Sunday October 15, 2006 @07:49PM (#16447465) Journal
        Could this study just be another chicken and egg concept and we havn't discussed wich came first?

        You mentioned when you are slimmer your less occupied with food and such. Your brain is noticibly performing better as you can notice the differences. It apears though that this study is gearded towards saying slim people are just smarter or have the ability to be smarter easier then fatter people. As if fat content in a prsons body directly reflect thier mental abilities.

        Now, What if the slimmer people have traditionaly concentrated on more mental work and less physicle work, therby training thier brain instead of thier muscles. Would this mean that a person who is slimmer is smarter because they are slimmer and less occupied with food or that they have traditionaly used thier brain more and remembering things or solving puzzles becomes more easy to them. Therefore a person with a larger build, spends more time not using thier brain and more on thier muscles, watching TV, or whatever else and thier ability to perform as well as the slim person is diminished?

        I remeber in third grade when we started multiplication. I used flash cards and could do almost any problem in my head that involved less then two numbers of two digits or less (20x7). After using calculators for a while, I could do this anymore. But I have been able to return to it becauseof vaious jobs ove rthe decades. (like roofing, framing and general construction working wich involves alot of math)

        So, from my personal experience, Could it be just how a slim person spends his time verses how a fatter person might? Obviously anyone who plays sports is going to be better then anyone who doesn't. And people playing for severla years will have somewhat of an advantage over those playing for a few weeks. Is this just the reverse were the game is a mind game instead of football? And someone with several years experience because of lifestyle differences will have an advantage over someone who doesn't exercise thier mind? Could it be that slim or fat is just a reflection of how a person spends thier time and has nothing or little to do with thier fat content outside what a fat person does compared to a skinny person.

        I would like to see this studdy done again and the occupations of the people be part of it. I would bet some one of larger BMI who does something like programing or construction were he reads blueprints, sets grades, or transferes scale to live building projects might do a little better then someone who is just fat and works at wopper floppers of america. But if the burger king employee of the month does the same as one of the others of same BMI, I would conceed that fat might have an impact.
        • Re: (Score:3, Interesting)

          by Aceticon ( 140883 )
          How about this:
          - Poorer people are fatter because they eat more junk food and cheap, rich in carbo-hydrates food (like potatos or rice) instead of healthier (and usually more expensive) food such as vegetables, lean meat, olive oil, etc...
          - At the present, intellectual work is more highly regarded and beter payed than manual work. This means that the poor tend to be those with lesser abilities to do intelectual work (people with lower IQs or those who didn't had a opportunity to get a good education).

          This c
    • Re: (Score:2, Informative)

      by maetenloch ( 181291 )
      I'm a big non-fan of the BMI as well. I lift weights and have quite a bit of muscle for my height, yet by the BMI charts I'm obese even though my body fat is relatively low. Unfortunately life insurance companies and many doctors take it as a reliable statistic for determining whether you're fat or not. Even the military uses it for checking if you're overweight. However so many buff guys were failing it yet were in excellent shape, that they now allow you to take a body fat test if you fail the BMI requir
      • Re: (Score:3, Interesting)

        by CastrTroy ( 595695 )
        I don't lift weights or work out, other than riding my bike to work in the summer. However, the BMI also says i'm overweight. I'm not, and I don't think most people would say I was if they looked at me, but for some reason, I'm unusually dense. I sink when I go in the water. For no apparent reason. If I inhale a lot of air, I will float, but for the most part I sink, and if I exhale most of my air, I sink like a rock. I always did bad in swimming lessons because I couldn't swim the long distances requ
    • by Rosco P. Coltrane ( 209368 ) on Sunday October 15, 2006 @05:42PM (#16446407)
      The Body Mass Index is not accurate. It is basically mass vs height, and makes no distinction between fat and muscle, both of which increase mass measurements.

      Sounds right then, most body builders I've met aren't exactly bright...
    • So BMI isn't perfect. But it's clearly better than pure weight numbers, since it's adjusted for height.

      Do you have an alternative easily computed number you think better measures obesity?

      Or do you just think we should not try to measure it?
    • Re: (Score:3, Interesting)

      The BMI: Body Mass Index = m/h^2.

      Density: p = M/V

      The above formulae clearly illustrate the problem with the BMI. The BMI in SI units would be kg/m^2, whereas the density is kg/m^3. Further the m^2 is from only one dimension, rather than from three mutually normal dimensions. The purpose of the BMI is to determine adiposity. For this purpose it may serve as a semi-useful metric in statistical studies of a epidemiological, or actuarial nature.

      However, as a diagnostic metric in a clinical setting it is worse t
  • BMI = Worthless (Score:5, Insightful)

    by Smidge204 ( 605297 ) on Sunday October 15, 2006 @05:24PM (#16446171) Journal
    (Of course, this sidesteps discussion of whether IQ tests measure anything significant at all.)

    This also seems to sidestep discussion of whether BMI measures anything significant at all.
    • Re:BMI = Worthless (Score:5, Interesting)

      by Keebler71 ( 520908 ) on Sunday October 15, 2006 @05:51PM (#16446493) Journal
      (Of course, this sidesteps discussion of whether IQ tests measure anything significant at all.)

      Concur but I have a different take on this wording. Of course IQ tests measure something significant. The question may be whether or not "IQ tests are a signigicant measure of anything at all". My wife is an elementry teacher and we recently discussed how children are placed into gifted classes. She said that they used to do IQ testing but that has fallen out of vogue due to their being a rather politically incorrect measure (not to mention all the other types of "intelligence" (emotional, creative, et crappra)). This is sad. IQ tests are a near-perfect indicator of intelligence. That is they have a very low incidence of Type I (false positive) error. The cultural biases come into play and lead to false negatives (Type II errors). It seems the logical approach would be to use a combination of tests or qualitative assessments rather than ditching a good but non-perfect test.

      • Re:BMI = Worthless (Score:4, Interesting)

        by tverbeek ( 457094 ) on Sunday October 15, 2006 @07:48PM (#16447457) Homepage

        IQ tests are a reliable measure of one's ability to perform well on IQ tests. You may choose to call that "intelligence" and wrap it all up in a tidy tautology, but that doesn't really prove anything.

        While debating the methodology of a study is valuable and worthwhile activity, it tends to get in the way of what generalizations can be drawn from the data. Since there is a strong positive correlation between BMI and actual obesity (even if that correlation is not 1.0 due to factors such as highly muscular individuals), and there is a strong positive correlation between IQ tests and actual intelligence (due to cultural and educational testing biases) this data identifies a negative correlation between obesity and intelligence. That's interesting and potentially useful. Now it's time for studies with more precise methodology.

    • Re:BMI = Worthless (Score:5, Insightful)

      by griffjon ( 14945 ) <> on Sunday October 15, 2006 @06:57PM (#16446995) Homepage Journal
      All of this conveniently ignores that correlation is not causation. maybe being stupid correlates with not taking care of yourself? Maybe they're both caused by a third variable (perhaps watching too much TV?)
    • by irritating environme ( 529534 ) on Sunday October 15, 2006 @07:04PM (#16447061)
      BMI and IQ aren't perfect measurements of their stated goal. They at least provide an approximation though.

      It is the people who don't think they mean anything at all usually are either fat or stupid.
    • Re:BMI = Worthless (Score:5, Insightful)

      by rjstanford ( 69735 ) on Sunday October 15, 2006 @07:10PM (#16447115) Homepage Journal
      I used to be in the "BMI == Worthless" camp myself. Had all sorts of reasons why it was bunk, used to be able to quote muscle density, et cetera, just like everyone else on here.

      Then I grew up and lost over 80 pounds.

      Anyone who show as "obese" on the BMI charts but has enough muscle to throw things off is obviously either way toned, or way strong. Seriously. If you're an average person, even a once or twice a week gym habit, and you show as obese... then you're 99% probably fat. Grow up and admit it. Especially in the USA, "normal," is a long way from "fit." The vast, vast majority of people with high BMIs are fat, end of story.

      Sure, Tom Cruise is the poster child for "overweight by BMI standards." He's obviously not. If you can see your sculpted abs, you probably aren't as well. Otherwise, you are. Deal with it.

      If you want to ignore it, that's your decision. Be overweight. But stop pretending you're not. And also, more to the point, stop trying to convince everybody else that they're not overweight because you can't deal with your own issues. And yes, that is a more generic rant than just one aimed at the parent poster, but its still true.
  • This has frightening implications for the majority of us /.'ers
  • IQ Tests (Score:5, Informative)

    by stevemm81 ( 203868 ) on Sunday October 15, 2006 @05:27PM (#16446207) Homepage
    (Of course, this sidesteps discussion of whether IQ tests measure anything significant at all.)

    This wasn't a general purpose IQ test. It was a specific test of people's ability to recall words. They're talking about memory in particular, not some fuzzy idea of general intelligence.
    • Re: (Score:3, Insightful)

      by r00t ( 33219 )
      Even if not, the comment is idiotic.

      It's sour grapes, political correctness, and anti-science. We damn well do know that people with high IQ are usually more successful than those with low IQ. This is especially true if you compare an IQ 80 person to an IQ 115 person. (rather than 140 and 170, where social problems can make things interesting)

      IQ is unpopular because it is mostly in-born, inheritable, and unevenly distributed. There is a sort of unfairness that goes against Western ideals. The idea that anyb
      • Re:IQ Tests (Score:5, Insightful)

        by Garse Janacek ( 554329 ) on Sunday October 15, 2006 @07:26PM (#16447261)

        We damn well do know that people with high IQ are usually more successful than those with low IQ.

        True, but (as shouldn't even have to be pointed out in this discussion) correlation does not imply causation. Specifically: when people are given better education, their IQ increases. IQ is decidedly not (as you claim) "mostly in-born [and] inheritable" unless you really believe that there is a measurable sense in which whites are inherently (on average) intellectually superior to blacks and hispanics in the United States.

        Now, even aside from any issues of political correctness, I hope you aren't in fact claiming that, because it's been pretty thoroughly refuted. If you take someone (of any race) out of poverty and give them a good education, their average IQ increases dramatically. While in any group (including those in poverty) there will be certain extraordinary individuals who have a high IQ (or whatever positive attribute you're measuring) despite all disadvantages, the frequency of these individuals goes up an awful lot if you take away the disadvantages in the first place.

        The reason some people dislike IQ, or claim it does not measure anything useful, is that most discussions about it implicitly assume that it succeeds in its goal of measuring intellectual capacity independently of cultural and educational factors. In this it fails completely. Which doesn't mean that it isn't measuring anything useful, but your comment shows there are still plenty of people who think IQ is some sort of "in-born" attribute. It's not.

        There is a sort of unfairness that goes against Western ideals. The idea that anybody can pull themself up out of poverty, that every child has a chance to succeed intellectually, is threatened by this.

        I'm actually kind of with you on this. I don't think the world is as fair as a lot of people would like to believe, and I don't think that anyone can pull themselves out of poverty, everyone has a chance to succeed, etc. -- and even though I think IQ is (mostly) bunk, I think some amount of intelligence is inborn. But nowhere near all. Even people who could have been very successful intellectually can fail because of their surroundings. All of which suggests, to me anyway, that it is important to do what we can to help others out of poverty and to provide children with good educations, since they may not be able to attain these things themselves regardless of their actions (that is, unlike some Americans, I don't see poverty as a moral failing).

        But, as I said, the fact that the world isn't fair doesn't mean it's unfair in the particular way you suggest, that is, that IQ is an innate property transcending culture, language, and education, and rich folks just happen to be innately the smartest.

        • Re:IQ Tests (Score:4, Interesting)

          by Somnus ( 46089 ) on Monday October 16, 2006 @12:39AM (#16449279)
          The puzzle is that IQ shows both high heritability (by studies of separated twins) and bias towards industrialized nations (Flynn Effect).

          The obvious theory is that both genetics and child care (nutrition, education) are vitally important.
        • Re: (Score:3, Interesting)

          I think some amount of intelligence is inborn. But nowhere near all.

          IQ is meant to measure exactly what you're describing -- the inborn intelligence that is relatively non-plastic after birth (or at least the first few years of development.) Decades of research have been devoted to this, and supposedly it works -- at least within a given race and within a given culture, in an industrialized society.

          Now, even aside from any issues of political correctness, I hope you aren't in fact claiming that, because

    • Re:IQ Tests (Score:5, Funny)

      by nizo ( 81281 ) * on Sunday October 15, 2006 @06:13PM (#16446679) Homepage Journal
      I bet the test was unfair; they should have asked the people who did poorly if they could, say, remember the items from a McDonald's menu. Now who has a better memory skinny boy!
  • by RsG ( 809189 ) on Sunday October 15, 2006 @05:29PM (#16446231)
    Not the study, but rather the first linked article.

    First, they make the classic error of attributing causation when the study found correlation. If that was in the original study, then I'd question the researcher's methodology, but I suspect the blame lies with whoever wrote the article. Testing people's intelligence and comparing their weight does not show a causitive link between wieght and intellect. It could just as easily show that poor judgement translates into bad eating habits and low IQ.

    Second, the criticism they reported came from a politician who tried to use anecdotal evidence to debunk the link. That's right, she said she knew witless skinny people and clever fat people, so the study must therefor be wrong. Someone ought to tell her that the plural of "anecdote" is not "evidence".
    • by Sique ( 173459 ) on Sunday October 15, 2006 @05:49PM (#16446461) Homepage
      It's the same as with the correlation of storks and newborn children: If you have many storks in a region, you can expect higher birthrates. This correlation is correct. It does not mean that the stork carries the newborn. Storks breed in rural areas, where they find their prey (mostly frogs and small rodents), and people in rural areas also tend to have more children than people living in cities.

      So obesity is (at least in Western and Central Europe, the study is french after all!) negatively correlated with the social status. People with low income tend to be more obese than people with high income. People with a high IQ also tend to have higher income than people with a lower IQ. Thus both correlations together tell you, that obese people have in average a lower IQ. If there is a causality, it may be this: Lower IQ -> lower wages -> more prone to obesity.
      • I mean consider the cost of good food vs bad food. I can go to McDonalds and get 2 double cheese burgers for $2 and some change. That's enough to fill me up for lunch and I'm a big guy. It's also a ton of fat and calories. Now let's say I want to go get a nice chicken salad from any of the number of places that serve them. That starts at about $6 and can be as much as $10. Also it's not going to fill me quite as much as the burgers.

        Is it any wonder those with lower income would opt for the McDonalds food?

  • As a fat man... (Score:3, Interesting)

    by Babbster ( 107076 ) <> on Sunday October 15, 2006 @05:29PM (#16446233) Homepage
    I can speak for certain that I am not as dumber as other people.

    Seriously, though, I test pretty well for intelligence, but being fat is part of a vicious cycle with laziness and depression, leading to a lack of achievement. I wonder, in fact, if the results would be similar in the population of people with untreated major depression regardless of BMI. Based on no scientific data at all, I would suspect increased BMI as being a symptom of another problem which could be the causative factor in the poor IQ showing.
    • by PigleT ( 28894 )
      You're probably onto something.

      As for causation: so if I run around a hill a few times, I'll get cleverer again?
  • I dunno (Score:4, Insightful)

    by TubeSteak ( 669689 ) on Sunday October 15, 2006 @05:30PM (#16446241) Journal
    Can we draw any real conclusions without knowing their testing methodology, etc etc etc. How'd they normalize their data?

    This last bit from the TFA sums up how I feel about it:
    "But Ann Widdecombe, the former Tory minister, said that the research seemed unsustainable. "You just need to look around the world and you will see hundreds of thin nitwits and clever fat people,""

    It is worth pointing out that good looks & a tall height can be as relevant to your success in life as your weight.
  • by Goosey ( 654680 ) on Sunday October 15, 2006 @05:30PM (#16446251) Homepage
    IANAOR (I am not an obesity researcher), but it seems to be that this does not indicate lower IQ, but rather a lower energy level. I think it is a rather uncontroversial statement that those suffering from obesity have a much lower level of energy. I have experienced it myself during extended periods (several weeks or more) of not having regular exercise: You become lethargic, tired, and find it difficult to concentrate on things. I would imagine that this is a good indication of why those suffering obesity would score poorer on an IQ test.
  • Link with poverty (Score:5, Insightful)

    by Dr. Spork ( 142693 ) on Sunday October 15, 2006 @05:31PM (#16446261)
    In most industrialized countries and especially in the US, obesity is strongly correlated with low income. Since there is also a strong link between low income and low IQ scores, there may be no causal relationship at all between obesity and a lowered IQ.
  • beyond the issues that have been raised already (like BMI not being necessarly representative, IQ tests not being particularly good, etc), there's the following problem: Is the fact that you're fat makes you brain go to hell, OR, is it that idiots are more likely to not realise that there's 200-300 calories in a can of soda.

    My vote is on the later. Because honestly, I don't see anything about body fat that could affect your head (to -this- extent). So its almost certain that its people who don't have a me
  • What Words? (Score:5, Funny)

    by malvidin ( 951569 ) on Sunday October 15, 2006 @05:32PM (#16446273)
    How much do you want to bet that the words weren't types of food?
  • by Ranger ( 1783 ) on Sunday October 15, 2006 @05:35PM (#16446307) Homepage
    The French are calling us fat, lazy, and now stupid. Great, well at least we aren't a bunch cheese eating surrender monkeys. Time to eat some more pork rinds and watch American Idol. I hope I don't have to get out of my chair to find my remote. Found it. It was under a fold of fat. I also found my car keys.
  • by AxemRed ( 755470 ) on Sunday October 15, 2006 @05:36PM (#16446335)
    There are probably other factors involved here. For example, poverty has also been linked to obesity (in America.) And less intelligence can also be linked to poverty.

    So does obesity somehow lead to mental decline? Or are people who are less intelligent more likely to let their physical health deteriorate?
    Or maybe less intelligence leads to poverty which leads to obesity. Then again, it could be the other way around...

    Correlation does not equal causation. If I had to place a bet, I would say that the link between obesity and intelligence isn't biological like the article is inferring. There may be some kind of link there, but I bet that other factors are more influential.
    • by malsdavis ( 542216 ) * on Sunday October 15, 2006 @06:24PM (#16446757)
      "Correlation does not equal causation. [...] There may be some kind of link there, but I bet that other factors are more influential." yada yada yada, I think I know everything!

      I can't stand posts like this. You obviously have not read the academic report and therefor your conclusion about its fallacy are completely worthless. I have not read the actual report either but to hear you make an instant "it's probably due to this other factor" summary about something you have obviously not even read is infuriating!

      The primary task of academic studies is to identify the true reason for an observed correlation. Every researcher knows that "Correlation does not equal causation" and the fact that the report has been published in a respected journal means for definate that the researchers have taken steps to ensure other obvious factors - like the ones you mention - are accounted for.
  • Causality (Score:2, Insightful)

    by sc0p3 ( 972992 )
    This is probably mistaking causality.

    Being overweight doesn't make you stupid,

    being stupid means you have higher chance of getting over weight because you don't monitor diet/understand proper eating.

    • by Shados ( 741919 )
      As i just posted, thats very very true, however, there's more to it. A diet that would allow one to be fit (lots of fruits and veggies, lots of fish, etc), is probably more likely to enhance the brain's capabilities than coke + hamburger + chips twice a day.

      Whats almost 100% sure in my view, however, is that the actual body fat doesn't affect anything, or at the very least, very little compared to the above factor, and your explaination.
  • by bananaendian ( 928499 ) on Sunday October 15, 2006 @05:49PM (#16446475) Homepage Journal

    Obesity leads to poor health which leads to diffuculty in concentration, stress, lower attention span etc. Also obese people are (statistically) less educated, with lower self-esteem etc. All of which correlate very well with the findings of this study. In otherwords obesity correlates well with doing badly in tests (IQ or any) for various reasons - it does not lower your IQ.

    Any qualified sociologist could've made a fairly accurate hypothesis for the results of that study. But that's boring so people will want to see something in it ...

    Oh well..

    Dr. Doh! (NIMNO)
    National reseach Institute for the Mind Numblingly Obvious

  • Perhaps... (Score:5, Funny)

    by OpenSourced ( 323149 ) on Sunday October 15, 2006 @05:51PM (#16446497) Journal
    people with a low body mass index (BMI) could recall 30% more words in a vocabulary test than those who were obese

    Then perhaps people get fat because they can't remember they have already eaten.

  • Memory != IQ (Score:5, Informative)

    by mkiwi ( 585287 ) on Sunday October 15, 2006 @06:17PM (#16446705)
    It is common in society to associate people with good memories as people with high IQ's.

    This is simply not true. If you actually take an IQ test, you will see that it does not test your memory as had been done in the study, but rather your cognitive thinking skills. In fact, there are many people who can memorize history or math equations or whatever, but they come up far short when they have to apply the concepts they memorized.

    Again, memorization is not critical thinking, and memorization != IQ.

    • Re: (Score:3, Interesting)

      by Reziac ( 43301 ) *
      I've known retarded people who had eiditic memories, provided it was about something that interested them. So as you say, memory alone isn't necessarily a good guage of IQ.

      IQ is really more about how well you're able to use the data that's put in front of you. I remember the IQ tests they gave me in the 1st grade -- most of it was about puzzling out how one thing related to another thing. My favourite part was the "exploded boxes" section. I had no idea boxes came apart like that, but it made sense the mome
  • by davidsyes ( 765062 ) on Sunday October 15, 2006 @06:28PM (#16446791) Homepage Journal
    I think their little "test" failed to consider that people with larger BMI have Balanced Multiple Inputs, and their brains are more "distributed". It is a FACT that distributed nodes have slightly longer data pathways in fuller people than in smaller people.

    Their test is quite inflammable and uncindiary.
  • by buddyglass ( 925859 ) on Sunday October 15, 2006 @08:31PM (#16447801)
    There is a correlation between obesity and poverty. The average IQ of those in poverty is lower than that of those not in poverty. Simply based on those two facts, one would expect the average IQ of obsese individuals to be lower than that of non-obese individuals.
  • by AJZ ( 588720 ) on Sunday October 15, 2006 @09:57PM (#16448323)
    First, because I haven't seen anyone point it out yet, the actual journal article is Neurology 2006;67:1208-1214. Go to 50 [] and the server will redirect you appropriately. The journal's Web site should let you read the abstract for free. To read the whole article, you have to pay, or find a suitable institution with online or print access to this journal.

    Now, some comments. The idea that correlation doesn't imply causation is correct, but this paper used a multivariate analysis to attempt to control for several possible confounding factors. I count twelve that the authors thought about and included in some of their models: age, sex, educational level, diabetes, systolic blood pressure, daily alcohol intake, physical activity, perceived health score, perceived stress score, energy, social isolation, and region of residence. It looks like the paper acknowledges more confounders than anyone's mentioned here on Slashdot so far. Ultimately, though, this paper is a cohort study, so you can still argue that they missed a confounding factor. If you can think of a legitimate one, you stand a good chance getting it published in the journal Neurology.

    Next, naming intelligent friends with high BMIs or famous thin people with questionable smarts does not change what this paper says, of course. Let's even pretend to add those people to the data. Now we have 2243 subjects instead of 2223. I doubt that changes the results much, but I admit I can't prove that. Counterexamples do tell us something very important, though. If high BMI really causes worse word-list learning, it is still one of a staggering number of other effects on this measure, and it by no means excludes anyone from higher intelligence.

    Lastly, people are right to wonder what cognitive tests like word-list learning really measure. This paper didn't use IQ directly, but the point still stands. The authors know this and address it, too. "The functional significance of cognitive changes in our sample is difficult to assess.... We did not collect any direct index of work performance." In fact, they don't know whether differences in these psychometric test scores apply to "this healthy working population." BMI, too, may represent a surrogate marker. The association in this paper still stands, although I don't see anything about whether active weight loss attempts change cognitive point measures or decline. Yes, there are other markers of cardiovascular risk, and these include waist circumference (Am J Cardiol 2006;98:1053-1056), which someone could study in the same way that the Neurology paper studies BMI.

    So what's the point? The point is, the differences in these cognitive tests concern some people. The results suggest that some real effect on cognition exists, and the authors mention a few reasonable mechanisms for the effect. If you agree that a normal BMI leads successively to less diabetes, less coronary artery disease, and less chest pain when you walk around, then it makes sense to try for a normal BMI if it's even possible that it will save blood vessels in your brain, or your brain cells directly, or whatever mechanism you believe. It wouldn't surprise me, though, if weight loss merely slows cognitive decline or lessens the risk, rather than positively improving intelligence or some similar claim. The other point is that newspapers check sources and strive to do it very well, but they rarely offer substantial analysis of original research. They will quote authorities regarding the research but leave item-by-item discussion to commentary articles in specialty journals. Even my couple hundred words here only begin to address the reasonable analysis of this or any scholarly article.
  • by wonkavader ( 605434 ) on Sunday October 15, 2006 @10:27PM (#16448517)
    No, of course not. We're fat BECAUSE we're stupid.
  • by chartreuse0 ( 886927 ) on Monday October 16, 2006 @01:31AM (#16449541)
    I went back and read the actual paper upon which this article is based, and the summary given on Slashdot is rather inaccurate. This article does not claim to compare "normal" weights to "obese" weights. Rather, it purports to show a trend primarily within the normal range of BMI.

    In particular, they broke up BMI's into five groups: (1) 15-21.5, (2) 21.5-23.4, (3) 23.4-25.2, (4) 25.2-27.7, and (5) 27.7-45, where BMI's up to 25 are considered normal, up to 30 are considered overweight, and over 30 are considered obese. Even within the final group, not all the participants are obese.

    It begs the question of why they didn't compare "normal" weight IQ's to "obese" weight IQ's, as this would be a big story and a more impressive research finding! It's likely that either they didn't have enough obese participants to satisfy statistical significance (so most of group (5) is actually individuals with BMI's of 27.7 to 30), or they didn't find that obese people had lower IQ's. When the BMI groups that they break up their data into as strange as this, and not at all the groups that are normally used in research papers, it begs the question of what kind of data massaging they had to do to find their conclusions. Did they try 100 different breakdowns of BMI groupings until they found one that (barely) satisfied statistical significance?

    I remain skeptical as to the conclusions of this paper.

  • by Kjella ( 173770 ) on Monday October 16, 2006 @06:54AM (#16450799) Homepage
    is not what it measures - if you put it together with "How often do you work out?" you have a pretty good idea how much is fat, and how much is muscle. People who want to delude themselves will always find a way (try blaming your metabolism, your hectic life style, "you'll never see me in the gym with those" jockophobia etc). The biggest problem is that people decide to "get in shape" and use weight as their result metric. That typically means eating less and more exercise - except more exercise means more muscle and often a greater appetite. The difference between losing two pounds of fat versus losing five pounds of fat and gaining three in muscle, both for a net loss of two, is huge. Hell, even losing two pounds of fat and gaining three pounds of muscle would typically be an improvement both to your health and your figure, even if it's a net gain. For example a good way to "offset" the focus on weight could be for example taking your waist measure - if you've lost five cms of belly and put it anywhere else, chances are you look a lot better no matter your weight. For women this should hardly come as a surprise (combine with chest and hips for the classic three). That should get the measuring straighted out a bit.

    The other question is what your BMI "should" be, but in my opinion it's fairly easy to tell when you have low body fat. People might be slender or muscular, but it's hardly a problem seeing if they have the kilos in the right place or not. It's simply a rough estimate of where your body should be given average muscles. Want to add 20 pounds of muscles? No problem. Just be sure you're not making it an excuse not to lose those last twenty pounds of fat. Check your abs, your measures, try the "jiggle" test and see if it's as firm as you want. There's plenty good metrics to use, and BMI is a good one used in conjunction with others. People that are problematizing measuring healthiness is using a Chewbacca tactic - that's not where the problem lies at all. Most of them just want a way to say "Because the metrics are imperfect, we can ignore the conclusions." That might work to disregard one dissenting metric, but if your BMI is too high AND your waist is too wide AND you aren't working out enough to build that kind of muscle AND everything jiggles when you walk then no way.

Never buy from a rich salesman. -- Goldenstern