TCS Daily


The Empire of Alarmists Strike Back

By John Luik - June 8, 2005 12:00 AM

"We don't want people to artificially hide controversies. We want to get them out in the open."
-- CDC Director Dr. Julie Gerberding, June 2, 2005

It's funny how quickly CDC Director Julie Gerberding has stopped sounding like a scientist and started talking like a character out of 1984.

Just over a month after the Centers for Disease Control researchers published a new study with a dramatically lower estimate of the number of Americans who die each year from obesity -- a study that found that being overweight did not lead to premature death -- the true believers in the doctrine that fat kills, led by Gerberding, are on the counterattack. Even as Gerberding was holding her most recent news conference, scientists at the Harvard School of Public Health, The American Heart Association and the American Cancer Society were busy telling the media that the CDC's figures were flawed. As ABC News reported on June 2, "Health experts increasingly are faulting a recent study by scientists at the federal Centers for Disease control and Prevention...Scientists from the Harvard School of Public Health, the American Heart Association and the American Cancer Society now uniformly reject those conclusions [that only 25,814 people die from obesity each year and the overweight have a lower risk of dying than those of normal weight]."

And it wasn't just the Harvard, Heart and Cancer people who appear to be rejecting the CDC's new figures. In the strangest twist yet in the saga of the missing fat corpses, Dr. Gerberding appeared to discount the work of her own scientific team led by Dr. Katherine Flegal, primary researcher of the new obesity mortality study, who was noticeably absent from Gerberding's latest news conference. Despite Gerberding's claim that she wanted to get the controversy over the CDC's obesity numbers "out in the open", it was clear that she was much more interested in making sure that everyone at the CDC and the media was back on message -- obesity kills and only massive government action can save us -- than in having a scientific debate about what the evidence shows.

Heart Disease, Cancer and Diabetes Questions

For instance, rather than admitting that the scientific evidence failed to support her previous claims about obesity being perhaps the leading cause of death in the US, Gerberding instead emphasized the ways in which obesity hastened death. Obesity, according to Gerberding, raises the risk of heart disease, some cancers, diabetes and arthritis, as well as increasing blood pressure and cholesterol, which also increases the risk of heart disease. And Gerberding's message about the life-threatening risks of obesity is echoed on the CDC's website where the new study is discussed. Under the question "What does this study mean to you?" the CDC provides what purports to be a summary of the relevant facts about obesity in the US. Fact one states that "Obesity remains an important cause of death in the United States...."

But this claim, like so much that the CDC and its director say about obesity these days needs to be taken with considerable skepticism. For example, if you go to another CDC website, the National Center for Health Statistics and look at the current Vital Statistics Reports -- Vol 53, No. 17 March 7, 2005, which gives the most recent data on causes of death in the United States you will not find any entry for obesity as a cause of death. It isn't just that obesity isn't one of the 10 leading causes of death, it is rather that obesity simply isn't a cause of death reported by the Center. In other words, the Center doesn't track or report "obesity" deaths. Nor does the International Classification of Diseases have a category of disease called obesity. So just how does the Centers for Disease Control know that "obesity remains an important cause of death in the US" when its own National Center for Health Statistics doesn't have a cause of death category called obesity?

Heart Disease

The answer must be found in what Gerberding said at her new conference, being overweight and obese kills people through heart disease, cancer and diabetes. But is this really true? Take high blood pressure for instance. The second National Health and Nutrition Examination Survey (NHANES II), used by the CDC in its obesity mortality survey, which followed 20,000 people from 1976-1980, found that there was a stronger association between extra lean tissue and high blood pressure than between extra fat tissue and high blood pressure. Several studies have also found that the reason for higher BMI's in people with hypertension is their continual yo-yo dieting, not their extra pounds. Or take the famous Framingham Heart Study which found that after thirty years, the men who had gained weight and had higher blood pressure had mortality rates from heart disease that were 50% less that those who had lost weight.

The evidence about obesity and heart disease is equally interesting in failing to support Dr. Gerberding's claim about a link between obesity and mortality. The largest angiographic examination of its kind, Applegate et al 1991, examined the angiograms of over 4500 middle aged and elderly men and women to determine the link between cardiovascular disease and obesity. What the study found was that weight was actually protective from heart disease in that for every 11 pound increase in body weight there was a 10-40% lower risk for atherosclerosis. Ultrasound analysis of obesity and heart disease has found similar results. For instance, the Atherosclerosis Risk in Communities study, published in the American Journal of Epidemiology in 2002, found that progression to heart disease was not linked to BMI.

None of this should be surprising to Gerberding since her CDC colleague, Dr. Edward Gregg recently published a study " Secular Trends in Cardiovascular Disease Risk Factors According to Body Mass Index in US Adults" which looked at the connection between obesity and risks for cardiovascular disease. Unlike his boss, however, who seems quite clear that obesity causes disease and premature death, Dr. Gregg is much more reticent, preferring to base his claims on the scientific evidence as opposed to faith. What Gregg found was that the risk factors for heart disease had "declined considerably over the past 40 years in all BMI groups", despite the fact that the prevalence of obesity has increased. In fact, the greatest declines in risks for heart disease were found in the overweight and obese. But perhaps Dr. Gerberding is so busy with the media that she hasn't had time to read Dr. Gregg's study.

Cancer

But what about cancer? After all, the American Cancer Society's Dr. Michael Thun is one of those questioning the CDC's revised figures. Perhaps those who are overweight or obese really do run a greater risk of dying from cancer. If we look to Dr. Thun's own study, "Overweight, Obesity and Mortality from Cancer "published in 2003, which created shock headlines across the country, it appears that obesity is a significant risk for cancer. But then looks can be deceiving in the obesity epidemic game. For instance, in overweight men, being overweight was actually protective against cancer death, rather like the CDC's own finding which Dr. Thun wishes to discredit. Indeed, across all populations, men and women, relative risks (RRs) were less than 2, suggesting lack of a meaningful association. Even more surprising was the fact that morbidly obese women -- that is women with BMI's in excess of 40 -- had less chance of dying from cancer than "normal" weight men, a very curious finding given the supposedly killer status of obesity.

Again, these results about cancer and obesity should not be surprising. Glenn Gaesser of the University of Virginia has suggested that over the last three decades that there have been 35-40 studies that have found a lower risk of cancer for those with higher BMI's. For instance, a large study by the National Cancer Institute of people with lung cancer found that women who had never smoked and had normal BMI's had a 140 per cent higher risk for getting lung cancer than overweight women. Again, a study in the Journal of Clinical Epidemiology (1990) concluded that "Neither coronary heart disease nor cancer, the two leading causes of death, was significantly associated with BMI." The Seven Countries Study which has followed the lives and deaths of 13,000 men over the last 40 years found that the risk of death from cancer decreased with increasing weight. And in a major review of the available evidence, researchers Ernsberger and Haskew concluded that in virtually every study total cancer death rates declined with rising BMI's

Diabetes

This leaves us with diabetes as Dr. Gerberding's final example of how obesity leads to premature death. Yet even here the evidence does not support the CDC director. Despite claims by many about a diabetes epidemic, the evidence suggests that the over the 1990's -- when obesity rates have supposedly skyrocketed by over 60% -- Type 2 diabetes incidence increased from 8.2 to 8.6%. As the Gregg study pointed out, total diabetes increased by only 1-2 percentage points from 1976-2000. Among Type 2 diabetics, those who are overweight have lower mortality rates than those with normal BMI's.

As for the role of obesity in diabetes, there is a significant amount of evidence that people who diet are more likely to get the disease than those who don't and that changes in physical activity and diet greatly reduce the risks of the disease independently of weight.

None of this, of course, found its way into Dr. Gerberding's news conference, despite the fact that it is a major part of the scientific literature about obesity, disease and mortality. Instead, Gerberding and the folks at the Heart Association and Cancer Society appear to want Americans to believe that the only evidence suggesting that there isn't a connection between being fat and dying early is the CDC's new study. Controversy and an open discussion of the evidence is the last thing they really want because the evidence is just too inconvenient for the doctrine that fat kills.

But the evidence and the controversy are not going away. There are dozens of studies, from around the world over the last four decades that show that being overweight and obese are not associated with disease or early death. If Dr. Gerberding is really committed to an evidence-based discussion of obesity in America, as opposed to a faith-based crusade, she might want to call a news conference to talk about them.

John Luik is writing a book about health policy. He lives in Canada.

Categories:
|

TCS Daily Archives