[Paleopsych] Skeptical Inquirer: Obesity: Epidemic or Myth?

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Obesity: Epidemic or Myth?

    New evidence shows that the obesity epidemic is not as bad as we have
    been led to believe. However, that doesnt mean that we should dismiss
    the problem either.


    You have probably heard that we are in the midst of an obesity
    epidemic. The Centers for Disease Control and Prevention (CDC) have
    been fervently warning that we are in imminent danger from our
    expanding waistlines since the beginning of this decade. However,
    evidence has recently emerged indicating that the CDCs warnings were
    based on questionable data that resulted in exaggerated risks.

    This new evidence has led to a hostile backlash of sorts against the
    CDC. The editors of the Baltimore Sun recently called the earlier
    estimates the Chicken Little Scare of 2004. The Center for Consumer
    Freedom, a group that has long been critical of the CDC, declared
    unequivocally on its Web site and in print ads in several newspapers
    around the country that the obesity scare was a myth (figure 1). Even
    Jay Leno poked fun at the CDC in one of his Tonight Show monologues,
    making the observation that not only are we fat. . . . We cant do math
    either. Not everybody believes the new data, however. Cable talk show
    host Bill Maher commented during an episode of his show Real Time with
    Bill Maher about it being a shame that lobbyists were able to
    manipulate the CDC into reducing the estimated risk.

    So which is it? Are we in imminent danger, or is the whole concept a
    myth? Looking at the scientific evidence it is clear that the extreme
    views on either side of the argument are incorrect. There is no doubt
    that many of our concerns about obesity are alarmist and exaggerated,
    but it is also apparent that there is a real health risk associated
    with it.

The Controversy

    Between 1976 and 1991 the prevalence of overweight and obesity in the
    United States increased by about 31 percent (Heini and Weinsier 1997),
    then between 1994 and 2000 it increased by another 24 percent (Flegal
    et al. 2002). This trend, according to a 2004 analysis, shows little
    sign of slowing down (Hedley et al. 2004). The fact that more of us
    are getting fatter all the time raises a significant public health
    concern. The Centers for Disease Control and Prevention (CDC) began
    calling the problem an epidemic in the beginning of this decade as the
    result of research that estimated 280,000 annual deaths as a
    consequence of obesity (Allison et al. 1999). Since then there has
    been a strong media campaign devoted to convincing Americans to lose
    weight. In 2003, Dr. Julie Gerberding, the director of the CDC, made a
    speech claiming that the health impact of obesity would be worse than
    the influenza epidemic of the early twentieth century or the black
    plague of the Middle Ages. In 2004 the campaign reached a fever pitch
    when a report was released that increased the estimate of
    obesity-related deaths to 400,000 (Mokdad et al. 2004). Finally, in
    March of this year, a report appeared in the New England Journal of
    Medicine that predicted a decline in life expectancy in the United
    States as a direct result of obesity (Olshansky, et al. 2005).

    Despite the assertions that obesity is causing our society great harm,
    however, many scientists and activist groups have disputed the level
    of danger that it actually poses. Indeed, a recent analysis presented
    in the Journal of the American Medical Association (JAMA) by Katherine
    Flegal of the CDC and her colleagues calls the severity of the dangers
    of excess body fat into question, indicating that the number of
    overweight and obesity-related deaths is actually about 26,000about
    one fifteenth the earlier estimate of 400,000 (Flegal et al. 2005).

    There is little argument about the fact that, as a nation, more of us
    are fatter than ever before; the disagreement lies in the effect that
    this has on our health. The campaign to convince us to lose weight
    gained much of its momentum in 2004; not only were there high-profile
    public health initiatives devoted to stopping the obesity epidemic,
    but the idea had pervaded popular culture as well. Movies like Morgan
    Spurlocks Super Size Me were the topic of many a discussion, and there
    were regular news reports about the dangers of too much fat.

    During this campaign, however, there were some notable dissenters.
    Paul Ernsberger, a professor of nutrition at Case Western Reserve
    University, has been doing research since the 1980s that led him to
    assert that obesity is not the cause of ill health but rather the
    effect of sedentary living and poor nutrition, which are the actual
    causes. Another prominent researcher, Steven Blair, director of the
    Cooper Institute of Aerobics Research in Dallas, Texas, has been an
    author on several studies indicating that the risks associated with
    obesity can be significantly reduced if one engages in regular
    physical activity, even if weight loss is not present. According to
    Blair, weight loss should not be ignored but a greater focus should be
    placed on physical activity and good nutrition. Both Ernsberger and
    Blair indicated to me that they thought the new research by Flegal and
    her colleagues provides a more accurate picture of the mortality risk
    associated with obesity.

    Figure 1. This advertisement, paid for by the Center for Consumer
    Freedom (CCF), ran in magazines and newspapers across the country. The
    ad was issued in response to the study in the Journal of the American
    Medical Association that found obesity-caused death rates had been
    exaggerated. However, CCF, an advocacy group for restaurants and food
    companies, has its own agenda.

    While scientists like Ernsberger and Blair have been presenting their
    conclusions in the scientific forum, others have taken a more
    inflammatory approach. In his 2004 book, The Obesity Myth, Paul Campos
    argues that the public health problem we have associated with obesity
    is a myth and further claims that our loathing of fat has damaged our
    culture (see Benjamin Radfords review on page 50). The most
    antagonistic group, however, is the Center for Consumer Freedom (CCF)
    (www.consumerfreedom.com), which implies that the obesity epidemic is
    a conspiracy between the pharmaceutical industries and the public
    health establishment to create a better market for weight-loss drugs.
    Numerous articles on the organizations Web site bash several of the
    most prominent obesity researchers who have disclosed financial ties
    to the pharmaceutical industries. Paul Ernsberger echoed this
    sentiment. He told me that the inflated mortality statistics were all
    based on the work of David Allison, a well-known pharmacoeconomics
    expert. These experts create cost-benefit analyses which are part of
    all drug applications to the FDA. These self-serving analyses start by
    exaggerating as much as possible the cost to society of the ailment to
    be treated (obesity in the case of weight-loss drugs). The risks
    associated with the new drug are severely underestimated, which
    results in an extremely favorable risk-benefit analysis, which is
    almost never realized once the drug is on the market. Experts who can
    produce highly favorable risk-benefit analyses are very much in
    demand, however.

    The claims made by the CCF are given some credence by Ernsbergers
    corroboration; however, there is a noteworthy problem with their own
    objectivity. On their Web site they present themselves as a
    consumer-minded libertarian group that exists to promote personal
    responsibility and protect consumer choices. Upon closer examination,
    however, it becomes evident that the CCF is an advocacy group for
    restaurants and food companies, who have as much to gain by the threat
    of obesity being a myth as the pharmaceutical industry does by the
    danger being dire.

    It is clear that there are agenda-determined interests on both sides
    of the issue. Therefore, the best way to discern what is necessary for
    good health is to shift our focus away from the sensational parts of
    the controversy and look at the science itself.

Current Science and Obesity Risks

    In their recent article, Katherine Flegal and her colleagues (2005)
    point out that the earlier mortality estimates were based on analyses
    that were methodologically flawed because in their calculations the
    authors used adjusted relative risks in an equation that was developed
    for unadjusted relative risk. This, according to Flegals group, meant
    that the old estimates only partially accounted for confounding
    factors. The older estimates, furthermore did not account for
    variation by age in the relation of body weight to mortality, and did
    not include measures of uncertainty in the form of [standard errors]
    or confidence intervals. These authors also point out that the
    previous estimates relied on studies that had notable limitations:
    Four of six included only older data (two studies ended follow-up in
    the 1970s and two in the 1980s), three had only self-reported weight
    and height, three had data only from small geographic areas, and one
    study included only women. Only one data set, the National Health and
    Nutrition Examination Survey I, was nationally representative (Flegal
    et al. 2005). In their current investigation, Flegals group addressed
    this problem by using data only from nationally representative samples
    with measured heights and weights. Further, they accounted for
    confounding variables and included standard errors for the estimates.

    Obesity was determined in this analysis using each subjects body mass
    index, which is a simple height-to-weight ratio. A BMI of 18 to 24 is
    considered to be the normal weight, 2529 is considered overweight, and
    30 and above is considered obese. The data from this study indicated
    that people who were underweight experienced 33,746 more deaths than
    normal-weight people, and that people who were overweight or obese
    experienced 25,814 more deaths than the normal-weight folks. This
    estimate is being reported in the popular media as being one-
    fifteenth the earlier estimate of 400,000. However, conflating the
    categories of overweight and obesity this way is misleading.

    At first glance, it appears that underweight poses a bigger threat to
    our health than overweight and obesity, and that the earlier estimates
    were profoundly exaggerated. However, in this study the people who fit
    into the obese category actually experienced 111,909 excess deaths
    compared to normal-weight subjects. In contrast, those who were
    categorized as overweight experienced 86,094 fewer deaths than those
    who were normal weight. The figure of 25,815 is the difference between
    the obesity deaths and the overweight survivals. In the original study
    by David Allison and his colleagues (Allison et al. 1999) it is
    actually estimated that 280,000 deaths result from overweight and
    obesity and that 80 percent, or 224,000, of these deaths occurred in
    people who were in the obese category. However, the study by Mokdad
    and colleagues (2004), using the same methods developed by Allison et
    al., estimated 400,000 obesity-related deaths, and subsequently fueled
    much of the recent fervor surrounding the obesity epidemic. In this
    study, no distinction was made between overweight and obesity and the
    authors failed to distinguish between obesity, physical inactivity,
    and poor diet. All of these variables were simply lumped together.

    A few things become clearer after examining the data. First, it
    appears that our categories are mislabeled; being classified as
    overweight appears to give one an advantage (statistically, anyway)
    over those who are in the ideal weight range. [1] Moreover, it is
    inappropriate to consider overweight and obese as one group. Despite
    the current hype, the initial overestimation by Allison and his group
    was not as exaggerated as is being publicized; compared to that study,
    the new estimate is actually about half of the old number. Finally, it
    is apparent that many at the CDC were simply confirming their own
    biases when they accepted the estimate by Mokdad et al. The categories
    in that studythat was, intriguingly, co-authored by CDC director Julie
    Gerberding, which may provide some insight into why it was so readily
    acceptedwere far too broad to provide useful information. The fact
    that this flaw was ignored shows how easy it is to accept evidence
    that supports our preconceived notions or our political agendas.

    There is another problem inherent in all of the above mortality
    estimates. They are based on epidemiological data that show
    correlation but leave us guessing as to causation. Various factors are
    interrelated with increased mortalityobesity, inactivity, poor
    nutrition, smoking, etc. Yet, without carefully controlled
    experiments, it is hard to determine which factors causeand which are
    symptoms ofpoor health. This is a difficult limitation to overcome,
    however, because we cant recruit subjects and have them get fat to see
    if they get sick and/or die sooner. Most institutional review boards
    would not approve that sort of research, and furthermore I cant
    imagine that there would be a large pool of subjects willing to
    participate. There are, however, observational data that were
    collected with fitness in mind, which help to clarify the picture

    In 1970 researchers at the Cooper Institute for Aerobics Research in
    Dallas, Texas, began to gather data for a longitudinal study that was
    called, pragmatically enough, the Aerobics Center Longitudinal Study
    (ACLS). This study looked at a variety of different variables to
    estimate the health risks and benefits of certain behaviors and
    lifestyle choices. What set this study apart from other large-scale
    observational studies, however, was that instead of relying on
    self-reporting for variables like exercise habits, they tested fitness
    levels directly by way of a graded exercise test (GXT). A GXT requires
    a person to walk on a treadmill as long as he or she can with
    increases in speed and incline at regular intervals. This is the most
    reliable way we know of to assess a persons physical fitness.

    With an accurate measure of the subjects fitness levels, researchers
    at the Cooper Institute have been able to include fitness as a
    covariate with obesity. Analysis of the data obtained in the ACLS
    shows that there is a risk associated with obesity, but when you
    control for physical activity, much of that risk disappears (Church et
    al. 2004; Katzmarzyk et al. 2004; Katzmarzyk et al. 2004; Lee et al.
    1999). One study showed that obese men who performed regular exercise
    had a lower risk of developing cardiovascular disease than lean men
    who were out of shape (Lee et al. 1999).

    Steven Blair, who runs the Cooper Institute and was an author on all
    four of the above-mentioned studies, however, does not think obesity
    should be ignored. I do think obesity is a public health problem,
    although I also think that the primary cause of the obesity epidemic
    is a declining level of average daily energy expenditure . . . it will
    be unfortunate if it is now assumed that we should ignore obesity. I
    do not think that the [health] risk of obesity is a myth, although it
    has been overestimated. Blair believes that a focus on good nutrition
    and increased physical activity rather than on weight loss will better
    serve us.

    In spite of the fact that there are virtually no controlled clinical
    trials examining the effects of obesity in people, we can make some
    inferences from animal research. Investigations performed by
    Ernsberger and his colleagues have shown that, over time, weight
    cycling (temporary weight loss followed by a regain of that weight,
    otherwise known as yo-yoing) in obese laboratory animals increases
    blood pressure, enlarges the heart, damages the kidney, increases
    abdominal fat deposits, and promotes further weight gain (Ernsberger
    and Koletsky 1993; Ernsberger et al. 1996; Ernsberger and Koletsky
    1999). This indicates that the yo-yo effect of crash dieting may be
    the cause of many of the problems we attribute to simply being fat.

    Even though there is a health risk from being too fat, you can
    eliminate much of the potential risk by exercising. Moreover, it is
    probably a bad idea to jump from diet to diet given the negative
    consequences the yo-yo effect can have. According to another study
    published in JAMA, the risk of cardiovascular disease has declined
    across all BMI groups over the past forty years as the result of
    better drugs (Gregg et al. 2005).

    None of this means, however, that we should simply abandon our
    attempts to maintain a healthy weight; obese people had twice the
    incidence of hypertension compared to lean people and, most
    significantly, there has been (according to the above study) a 55
    percent increase in diabetes [2] that corresponds to the increase in
    obesity. So while we are better at dealing with the problem once it
    occurs, it is still better to avoid developing the problem in the
    first place.

Condemning the CDC

    Whatever side of the argument you are on, it is apparent that many in
    the CDC acted irresponsibly. However, despite the fact that the
    initial, exaggerated estimate came from people at the CDC, we should
    keep in mind that so did the corrected number. While this can be
    frustrating to the casual observer, it is also a testament to the
    corrective power of the scientific method.

    Science is about provisional truths that can be changed when evidence
    indicates that they should be. The fact that scientific information is
    available to the public is its greatest strength. Most of us, for
    whatever reasonwhether its self-interest or self-delusiondont view our
    own ideas as critically as we should. The fact that scientific ideas
    are available for all to see allows those who disagree to disprove
    them. This is what has happened at the CDC; the most current study has
    addressed the flaws of the earlier studies. It is true that many of
    those in power at the CDC uncritically embraced the earlier estimates
    and overreacted, or worse simply accepted research that was flawed
    because it bolstered their agendas. But that failure lies with the
    people involved, not with the CDC as an institution or with the
    science itself.

    The evidence still shows that morbid obesity is associated with an
    increased likelihood of developing disease and suffering from early
    mortality, but it also shows that those who are a few pounds
    overweight dont need to panic. Whats more, it is clear that everyone,
    fat or thin, will benefit from regular exercise regardless of whether
    they lose weight.

    The lesson to be learned from this controversy is that rational
    moderation is in order. Disproving one extreme idea does not prove the
    opposite extreme. As Steven Blair told me, It is time to focus our
    attention on the key behaviors of eating a healthful diet (plenty of
    fruits and veggies, a lot of whole grains, and not too much fat and
    alcohol) and being physically active every day.


    1. This is not the first time this has been shown. The following
    studies are also large-scale epidemiological studies that have found
    the overweight category is where the longest lifespan occurs: Waaler
    H.T. 1984. Height and weight and mortality: The Norwegian experience.
    Acta Medica Scandinavica Supplementum 679, 156; and Hirdes, J.,
    Forbes, W. 1992. The importance of social relationships,
    socieoeconomic status and health practices with respect to mortality
    in healthy Ontario males. Journal of Clinical Epidemiology 45:175182.

    2. This is for both diagnosed and undiagnosed individuals.


    Allison, D.B., et al. 1999. Annual deaths attributable to obesity in
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    Blair, Steven, and James Morrow, Jr. 2005. Comments on U.S. dietary
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    Campos, Paul. 2004. The Obesity Myth. New York, New York: Gotham

    Church, T., et al. 2004. Exercise capacity and body composition as
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About the Author

    Patrick Johnson is a biology instructor at Washtenaw Community College
    in southeast Michigan and a clinical exercise physiologist who writes
    frequently about health, nutrition, and fitness claims. He lives with
    his wife and his eight-year-old son. E-mail: johnsonp @wccnet.edu.

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