Junkfood Science: Losing sight of the evidence

August 15, 2007

Losing sight of the evidence

Most parents, doctors, policy makers and teachers have something in common. Their primary source for information on obesity and nutrition is the news. The sheer volume of reports, even in professional circles, urgently presenting an “Obesity crisis doomed to bring catastrophic repercussions if we don’t act now!” has reached such extremes, that increasingly more experts are speaking out and calling for people to carefully reexamine what they believe and look at the evidence.

Most people believe, for example, that there is a shocking epidemic of childhood obesity. They believe it must be true because they see the media’s picture of enormous fat children eating junkfood diets and plopped in front of the TV. Those headless adults of extreme size are believed to represent the obesity crisis among adults, too. Even the professional literature can be indistinguishable from the mainstream news in its portrayal of obesity.

The actual picture of fatness in our culture has changed much less over the last century than most people might imagine. There are still those naturally of all extremes of size and shape, but today we also have fewer low outliers skewing the national average down: fewer children sick with preventable childhood illnesses and without enough to eat, fewer people sick and dying of infections from contaminated water and from conditions modern medicine can treat, and fewer people starving in destitute poverty. Not only are there more aging people, more recently we've also become a much more ethnically diverse population than even just a few decades ago. As nations prosper, the average weight of the overall population slightly increases over decades — just as health and longevity improve.

“Health authorities in many Western countries point to generally improving health and declining levels of many of those diseases most often linked to overweight and obesity,” wrote Dr. Michael Gard of Charles Sturt University, Australia. This disconnect should bring us cause to pause and think carefully. Without correctly identifying the problem we are trying solve and understanding its actual causes — in this case believing that obesity is at the root of health problems and is caused by overeating bad foods and inactivity — can misguide us to “solutions” that actually don’t help anyone and hurt more.

Dr. Gard has released a paper looking at how much of the current thinking and policy on obesity ignores or acts against the evidence. Obesity and Public Policy: Thinking clearly and treading carefully is written for those who’ve never thought to question the popular groupthink on obesity. In it, he looks at some of what is known about obesity and raises ethical questions about anti-obesity initiatives, especially those directed at children. “The problem of generalising about the causes or cures for overweight and obesity becomes more pronounced the closer you look,” he said.

First, our so-called common sense assumptions often turn out to be wrong. Second, if our policy response to childhood obesity is to advise parents about how they should parent (or, indeed, to advise any of us about how we should live) then it is probably a good idea to base this advice on sound assumptions. Without this, policy interventions may end up looking like ill-conceived meddling in people’s personal lives.

He exampled that over the past 70 years the research is “remarkably consistent in that they show Western populations eating fewer calories and less fat as each decade has gone by.” And looking at the second part of the popular calories in-out theory, he writes:

A similar set of issues applies to physical activity. While a number of researchers have tried to demonstrate that Western populations do less physical activity, no empirical evidence to support this view exists. In fact, the evidence that does exist suggests that children and adults are either as physically active as previous generations or more so.

While people have taken sides, eager to blame “bad” food or inactivity, a crucial policy issue arises that no one is considering, he says:

The somewhat hysterical popular discussion about overweight and obesity has created the impression that every aspect of our lives promotes obesity (the concept of an ‘obesogenic society’). If we take this view at face value, the challenge for policy makers becomes simply overwhelming. In effect, the ‘war on obesity’ becomes a war on the totality of our lifestyles....

“Nowhere has the danger of hasty generalisations been more apparent than in the area of childhood obesity, technology and physical activity,” he said. He goes on to talk about the same issues and evidence examined here. “In the 1980s a group of influential obesity researchers pronounced that television viewing was producing a generation of ‘couch potatoes,’ said Dr. Gard.

Since that time a small army of researchers have set about proving the case against televisions and, more recently, computers. The research community seemed as convinced as the scores of politicians and journalists who simply assumed that televisions and computers caused children to be less physically active. However, as the research studies piled up, a very different picture emerged. Television and computer usage seems to have almost nothing to do with the amount of physical activity that children do and not all that much to do with how fat they are. In short, the apparently common sense connection between technology and childhood obesity has joined the long list of urban myths that the study of obesity seems to generate...

To begin with, it is well known that young people are the most physically active section of Western populations. However, research shows that physical activity [and our diet] is not like a ‘habit’ one forms in childhood and then repeats for the rest of one’s life....In other words, physical activity seems to be context dependent and research suggests that childhood physical activity level is a poor predictor of adult activity level. In other words, children are not wind-up dolls. The problem is not so much getting children interested in physical activity when they are young as encouraging people to become and remain physically active as they age. This point is all the more pertinent if we accept research discussed above suggesting that children may be as physically active as they have been in previous generations.

In my view, there is also an ethical dimension here. Much of the momentum for targeting physical activity in schools comes from the popular belief that childhood physical activity has long-term health benefits. However, there is almost no evidence to support this view and most health researchers concede this point...

As a physical education instructor, Dr. Gard is especially concerned of the ethical issue raised by public discourse and school curriculums that focuses on inactivity as the cause of dire health consequences and tells children that physical activity is “first and foremost a matter of public as well as personal health and that they could die young if they do not exercise regularly. This is not only untrue but also burdens children’s physical activity with an unnecessary and potentially counter-productive seriousness.” He goes on to describe what he sees in school physical activity programs that range from dull to dangerous:

Strenuous exercise and fitness testing of children, often using activities and tests that were designed for adults, place teachers at obvious risk of litigation if children are injured in any way. This is a particularly serious matter if unqualified staff are used to lead children’s physical activity sessions. However, in a more straightforward sense, there is good deal of research to show that children simply do not enjoy being forced to be physically active and that they particularly do not enjoy it if it is overly repetitive, uncomfortable or embarrassing.

Worse, children are being hurt by these obesity policies, from physical injury to eating disorders. School teachers simply don’t have the expertise to address obesity, he argues, and therefore, “are vulnerable to litigation, no matter how willing to play their part they are.”

We all need to stop and face some awkward dilemmas, he said, but even that has become hard because the talk surrounding the war on obesity has become a war between good and evil. That’s left everyone taking sides and those being blamed taking defensive positions. It has become popular to rally against fast food, for instance, although “research has found that the number of fast food outlets made no difference to childhood obesity,” he noted. Another initiative he said are the popular calls for “far reaching changes to the design of communities...their argument has been that there is an obvious link between urban sprawl and obesity. However, this assumed link may turn out to be much less robust.”

"We should never lose sight of the fact that Western populations are, by and large, as healthy as they have ever been,” he said. While some are predicting doomsday shortened life expectancies, the majority of evidence illustrates life expectancies that continue to rise. “It is impossible for both points of view to be correct,” he said. Most people would agree that we should be guided by the best evidence, yet research does not justify the actions of public policies in the war on obesity. And when we act on beliefs and politics, rather than careful consideration of the evidence, we risk doing more harm than good.

The Scottish Council Foundation has made Dr. Gard’s paper free to the public here.

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