[Paleopsych] NYT: Some Extra Heft May Be Helpful, New Study Says

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Some Extra Heft May Be Helpful, New Study Says
http://www.nytimes.com/2005/04/20/health/20fat.html
April 20, 2005

    By [1]GINA KOLATA

    People who are overweight but not obese have a lower risk of death
    than those of normal weight, federal researchers are reporting today.

    The researchers - statisticians and epidemiologists from the National
    Cancer Institute and the Centers for Disease Control and Prevention -
    also found that increased risk of death from obesity was seen for the
    most part in the extremely obese, a group constituting only 8 percent
    of Americans.

    And being very thin, even though the thinness was longstanding and
    unlikely to stem from disease, caused a slight increase in the risk of
    death, the researchers said.

    The new study, considered by many independent scientists to be the
    most rigorous yet on the effects of weight, controlled for factors
    like smoking, age, race and alcohol consumption in a sophisticated
    analysis derived from a well-known method that has been used to
    predict cancer risk.

    It also used the federal government's own weight categories, which
    define fatness and thinness according to a "body mass index"
    correlating weight to height, regardless of sex. For example, 5-foot-8
    people weighing less than 122 pounds are underweight. If they weighed
    122 to 164 pounds, their weight would be normal. They would be
    overweight at 165 to 196, obese at 197 to 229, and extremely obese at
    230 or over.

    Researchers had a full gamut of responses to the unexpected findings,
    being reported today in The Journal of the American Medical
    Association.

    Some saw the report as a long-needed reality check on what they
    consider the nation's near-hysteria over fat.

    "I love it," said Dr. Steven Blair, president and chief executive of
    the Cooper Institute, a research and educational organization in
    Dallas that focuses on preventive medicine.

    "There are people who have made up their minds that obesity and
    overweight are the biggest public health problem that we have to
    face," Dr. Blair said. "These numbers show that maybe it's not that
    big."

    Others simply did not believe the findings.

    Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's
    Hospital in Boston, which is affiliated with Harvard, pointed to the
    university's own study of nurses that found mortality risks in being
    overweight and even greater risks in being obese. (That study involved
    mostly white women and used statistical methods different from those
    in the newly reported research.)

    "We can't afford to be complacent about the epidemic of obesity," Dr.
    Manson said.

    In fact, the new study addressed the risk only of death and not of
    disability or disease. There has long been conclusive evidence that as
    people move from overweight to obese to extremely obese, they are more
    and more likely to have diabetes, high blood pressure and high
    cholesterol levels.

    But the investigators said it was possible that being fat was less of
    a health risk than it used to be. They mentioned a paper, also being
    published today in the journal, in which researchers including Dr.
    Edward W. Gregg and Dr. David F. Williamson, both of the C.D.C.,
    report that high blood pressure and high cholesterol levels are less
    prevalent now than they were 30 or 40 years ago, largely because of
    breakthroughs in medication.

    As for whether there is truly a mortality risk in being underweight,
    Dr. Mark Mattson, a rail-thin researcher at the National Institute on
    Aging who is an expert on caloric restriction as a means of prolonging
    life, said it was not clear that eating fewer calories meant weighing
    so little, since some people eat very little and never get so thin. In
    any event, while caloric restriction may extend life, Dr. Mattson
    said, "there's certainly a point where you can overdo it with caloric
    restriction, and we don't know what that point is."

    Some statisticians and epidemiologists said that the study's methods
    and data were exemplary and that the authors - Dr. Williamson and Dr.
    Katherine M. Flegal of the disease control centers, and Dr. Barry I.
    Graubard and Dr. Mitchell H. Gail of the cancer institute - were
    experienced and highly regarded scientists.

    "This is a well-known group, and I thought their analysis and their
    statistical approaches were very good," said Dr. Barbara Hulka, an
    emerita professor of epidemiology at the University of North Carolina.

    The study did not explain why overweight appeared best as far as
    mortality was concerned. But Dr. Williamson said the reason might be
    that most people die when they are over 70. Having a bit of extra fat
    in old age appears to be protective, he said, giving rise to more
    muscle and more bone.

    "It's called the obesity paradox," Dr. Williamson said. But, he said,
    while the paradox is real, the reasons are speculative. "It's raw
    conjecture," he said.

    The new study comes just 13 months after different researchers from
    the disease control centers published a paper warning that obesity and
    overweight were causing an extra 400,000 deaths a year and were poised
    to overtake smoking as the nation's leading preventable cause of
    premature death.

    That conclusion caused an uproar, and scientists, particularly those
    who examine the consequences of smoking, questioned the study's
    methods. In January, the agency's researchers corrected calculation
    errors and published a revised estimate of 365,000 deaths.

    Now the new study says that obesity and extreme obesity are causing
    about 112,000 extra deaths but that overweight is preventing about
    86,000, leaving a net toll of some 26,000 deaths in all three
    categories combined, compared with the 34.000 extra deaths found in
    those who are underweight.

    Dr. Donna Stroup, director of the Coordinating Center for Health
    Promotion at the C.D.C., noted that the previous study had used
    different data and different methods of analysis.

    "Counting deaths is not an exact science," Dr. Stroup said.

    For now, said Dr. Dixie Snider, the disease control centers' chief
    science officer, the agency will not take a position on what is the
    true number of deaths from obesity and overweight. "We're too early in
    the science," Dr. Snider said.

    Dr. Stroup said of the new findings, "From a scientific point of view,
    they are a step forward." But she added that the agency considered
    illness that is linked to obesity to be just as important as the
    number of deaths.

    "Mortality really only represents the tip of the iceberg of the
    magnitude of the problem," she said.

    Estimating deaths due to overweight or obesity is a statistical
    challenge, the study's investigators said. The idea is to determine,
    for each person in the population, what would be the risk of dying if
    that person's weight were normal.

    For people whose weight is already in that range, there would be no
    change in the risk, of course. But what happens to the risk for people
    whose weight is above or below the normal range? The idea is to
    control for factors like age, smoking and gender, and ask what would
    happen if only the weight were changed.

    Now that the researchers have done their analysis, Dr. Williamson
    said, the message, as he sees it, is that perhaps people should take
    other factors into consideration when deciding whether to worry about
    the health risks of their weight.

    Dr. Williamson, who is overweight, said that "if I had a family
    history - a father who had a heart attack at 52 or a brother who
    developed diabetes - I would actively lose weight."

    But "if my father died at 94 and my mother at 97 and I had no family
    history of chronic disease," he said, "maybe I wouldn't be as
    concerned."

    Dr. Barry Glassner, a sociology professor at the University of
    Southern California, had another perspective.

    "The take-home message from this study, it seems to me, is
    unambiguous," Dr. Glassner said. "What is officially deemed overweight
    these days is actually the optimal weight."

References

    1. http://query.nytimes.com/search/query?ppds=bylL&v1=GINA%20KOLATA&fdq=19960101&td=sysdate&sort=newest&ac=GINA%20KOLATA&inline=nyt-per