Obesity: An Overblown Epidemic?
A growing number of dissenting researchers accuse government and medical authorities--as well as the media--of misleading the public about the health consequences of rising body weights
Could it be that excess fat is not, by itself, a serious health risk for the vast majority of people who are overweight or obese--categories that in the U.S. include about six of every 10 adults? Is it possible that urging the overweight or mildly obese to cut calories and lose weight may actually do more harm than good?
Such notions defy conventional wisdom that excess adiposity kills more than 300,000 Americans a year and that the gradual fattening of nations since the 1980s presages coming epidemics of diabetes, cardiovascular disease, cancer and a host of other medical consequences. Indeed, just this past March the New England Journal of Medicine presented a "Special Report," by S. Jay Olshansky, David B. Allison and others that seemed to confirm such fears. The authors asserted that because of the obesity epidemic, "the steady rise in life expectancy during the past two centuries may soon come to an end." Articles about the special report by the New York Times, the Washington Post and many other news outlets emphasized its forecast that obesity may shave up to five years off average life spans in coming decades.
These critics, all academic researchers outside the medical community, do not dispute surveys that find the obese fraction of the population to have roughly doubled in the U.S. and many parts of Europe since 1980. And they acknowledge that obesity, especially in its extreme forms, does seem to be a factor in some illnesses and premature deaths.
They allege, however, that experts are blowing hot air when they warn that overweight and obesity are causing a massive, and worsening, health crisis. They scoff, for example, at the 2003 assertion by Julie L. Gerberding, director of the Centers for Disease Control and Prevention, that "if you looked at any epidemic--whether it's influenza or plague from the Middle Ages--they are not as serious as the epidemic of obesity in terms of the health impact on our country and our society." (An epidemic of influenza killed 40 million people worldwide between 1918 and 1919, including 675,000 in the U.S.)
What is really going on, asserts Oliver, a political scientist at the University of Chicago, is that "a relatively small group of scientists and doctors, many directly funded by the weight-loss industry, have created an arbitrary and unscientific definition of overweight and obesity. They have inflated claims and distorted statistics on the consequences of our growing weights, and they have largely ignored the complicated health realities associated with being fat."
The overweight segment of the "epidemic of overweight and obesity" is more likely reducing death rates than boosting them.
One of those complicated realities, concurs Campos, a professor of law at the University of Colorado at Boulder, is the widely accepted evidence that genetic differences account for 50 to 80 percent of the variation in fatness within a population. Because no safe and widely practical methods have been shown to induce long-term loss of more than about 5 percent of body weight, Campos says, "health authorities are giving people advice--maintain a body mass index in the 'healthy weight' range--that is literally impossible for many of them to follow." Body mass index, or BMI, is a weight-to-height ratio.
By exaggerating the risks of fat and the feasibility of weight loss, Campos and Oliver claim, the CDC, the U.S. Department of Health and Human Services and the World Health Organization inadvertently perpetuate stigma, encourage unbalanced diets and, perhaps, even exacerbate weight gain. "The most perverse irony is that we may be creating a disease simply by labeling it as such," Campos states.
On first hearing, these dissenting arguments may sound like nonsense. "If you really look at the medical literature and think obesity isn't bad, I don't know what planet you are on," says James O. Hill, an obesity researcher at the University of Colorado Health Sciences Center. New dietary guidelines issued by the DHHS and the U.S. Department of Agriculture in January state confidently that "a high prevalence of overweight and obesity is of great public health concern because excess body fat leads to a higher risk for premature death, type 2 diabetes, hypertension, dyslipidemia [high cholesterol], cardiovascular disease, stroke, gall bladder disease, respiratory dysfunction, gout, osteoarthritis, and certain kinds of cancers." The clear implication is that any degree of overweight is dangerous and that a high BMI is not merely a marker of high risk but a cause.
"These supposed adverse health consequences of being 'overweight' are not only exaggerated but for the most part are simply fabricated," Campos alleges. Surprisingly, a careful look at recent epidemiological studies and clinical trials suggests that the critics, though perhaps overstating some of their accusations, may be onto something.
Oliver points to a new and unusually thorough analysis of three large, nationally representative surveys, for example, that found only a very slight--and statistically insignificant--increase in mortality among mildly obese people, as compared with those in the "healthy weight" category, after subtracting the effects of age, race, sex, smoking and alcohol consumption. The three surveys--medical measurements collected in the early 1970s, late 1970s and early 1990s, with subjects matched against death registries nine to 19 years later--indicate that it is much more likely that U.S. adults who fall in the overweight category have a lower risk of premature death than do those of so-called healthy weight. The overweight segment of the "epidemic of overweight and obesity" is more likely reducing death rates than boosting them. "The majority of Americans who weigh too much are in this category," Campos notes.
Counterintuitively, "underweight, even though it occurs in only a tiny fraction of the population, is actually associated with more excess deaths than class I obesity," says Katherine M. Flegal, a senior research scientist at the CDC. Flegal led the study, which appeared in the Journal of the American Medical Association on April 20 after undergoing four months of scrutiny by internal reviewers at the CDC and the National Cancer Institute and additional peer review by the journal.
These new results contradict two previous estimates that were the basis of the oft-repeated claim that obesity cuts short 300,000 or more lives a year in the U.S. There are good reasons to suspect, however, that both these earlier estimates were compromised by dubious assumptions, statistical errors and outdated measurements.
When Flegal and her co-workers analyzed just the most recent survey, which measured heights and weights from 1988 to 1994 and deaths up to 2000, even severe obesity failed to show up as a statistically significant mortality risk. It seems probable, Flegal speculates, that in recent decades improvements in medical care have reduced the mortality level associated with obesity. That would square, she observes, with both the unbroken rise in life expectancies and the uninterrupted fall in death rates attributed to heart disease and stroke throughout the entire 25-year spike in obesity in the U.S.
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Workplace Cited as a New Source of Rise in Obesity
The New York Times: Fitness & Nutrition
by Tara Parker-Pope
A sweeping review of shifts in the labor force since 1960 suggests that a sizable portion of the national weight gain can be explained by declining physical activity during the workday. Jobs requiring moderate physical activity, which accounted for 50 percent of the labor market in 1960, have plummeted to just 20 percent.
The remaining 80 percent of jobs, the researchers report, are sedentary or require only light activity. The shift translates to an average decline of 120 to 140 calories a day in physical activity, closely matching the nation’s steady weight gain over the past five decades, according to the report, published Wednesday in the journal PLoS One.
Today, an estimated one in three Americans are obese. Researchers caution that workplace physical activity most likely accounts for only one piece of the obesity puzzle, and that diet, lifestyle and genetics all play important roles.
But the new emphasis on declining workplace activity also represents a major shift in thinking, and it suggests that health care professionals and others on the front lines against obesity, who for years have focused primarily on eating habits and physical activity at home and during leisure time, have missed a key contributor to America’s weight problem. The findings also put pressure on employers to step up workplace heath initiatives and pay more attention to physical activity at work.
“If we’re going to try to get to the root of what’s causing the obesity epidemic, work-related physical activity needs to be in the discussion,” said Dr. Timothy S. Church, a noted exercise researcher at the Pennington Biomedical Research Center in Baton Rouge, La., and the study’s lead author. “There are a lot of people who say it’s all about food. But the work environment has changed so much we have to rethink how we’re going to attack this problem.”
The report shows that in 1960, one out of two Americans had a job that was physically active. Now it is estimated that only one in five Americans achieves a relatively high level of physical activity at work. Dr. Church notes that because the research does not factor in technological changes, like increasing reliance on the Internet and e-mail, many people in service and desk jobs that have always involved only light activity are now moving less than ever, meaning the findings probably understate how much physical activity has been lost during work hours.
While it has long been known that Americans are more sedentary at work compared with the farming and manufacturing workers of 50 years ago, the new study is believed to be the first in which anyone has estimated how much daily caloric expenditure has been lost in the workplace.
“It’s a light bulb, ‘aha’ moment,” said Barbara E. Ainsworth, the president-elect of the American College of Sports Medicine and an exercise researcher at Arizona State University. “I think occupational activity is part of that missing puzzle that is so difficult to measure, and is probably contributing to the inactivity and creeping obesity that we’re seeing over time.”
For years, the role that physical activity has played in the obesity problem has been uncertain. Numerous studies suggest there has been little change in the average amount of leisure-time physical activity, posing a conundrum for researchers trying to explain the country’s steady weight gain. As a result, much of the focus has been on the rise of fast-food and soft drink consumption.
Other studies have suggested that changing commuting habits, declining reliance on public transportation and even increased time in front of the television have played a role in the fattening of America. But none of those issues can fully explain the complex changes in nationwide weight-gain patterns.
Some earlier research has hinted at the fact that workplace physical activity is associated with weight and health. One seminal set of studies of London bus drivers and conductors showed that the sedentary bus drivers had higher rates of heart disease than the ticket takers, who moved around during the workday.
Dr. Church said that during a talk on the country’s obesity patterns, he was struck by the fact that Mississippi and Wisconsin both had high rates of obesity, despite having little in common in terms of demographics, education or even weather. It occurred to him that both states had waning agricultural economies, prompting him to begin exploring the link between changes in the labor force and declines in workplace physical activity.
He quickly discovered that a decline in farming jobs alone could not explain increasing obesity around the country, and began exploring job shifts over several decades. Using computer models, Dr. Church and colleagues assigned metabolic equivalent values to various job categories and then calculated changes in caloric expenditure at work from 1960 to 2008.
“You see the manufacturing jobs plummet and realize that’s a lot of physical activity,” Dr. Church said. “It’s very obvious that the jobs that required a lot of physical activity have gone away.”
Ross C. Brownson, an epidemiologist at Washington University in St. Louis, said that both health professionals and the public needed to broaden the traditional definition of physical activity as something that occurred during planned exercise, like running or working out at the gym.
“We need to think about physical activity as a more robust concept than just recreational physical activity,” said Dr. Brownson, whose 2005 report on declining physical activity in the workplace is cited in the PLoS One report. “In many ways we’ve engineered physical activity out of our lives, so we’ve got to find ways to put it back into our lives, like taking walks during breaks or having opportunities for activity that are more routine to our daily lives, not just going to the health club.”
Researchers said it was unlikely that the lost physical activity could ever be fully restored to the workplace, but employers do have the power to increase the physical activity of their employees by offering subsidized gym memberships or incentives to use public transit. Some companies have set up standing workstations, and marketers now offer treadmill-style desks. Employers can also redesign offices to encourage walking, by placing printers away from desks and encouraging face-to-face communication, rather than e-mail.
“The activity we get at work has to be intentional,” Dr. Ainsworth said. “When people think of obesity they always think of food first, and that’s one side of it, but it’s high time to look at the amount of time we spend inactive at work.”
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