Junkfood Science: The Telly Tubby Myth

February 06, 2007

The Telly Tubby Myth

Laments over the sad condition of today’s children fill the media and even some professional literature. Their proclamations appear to verify what is popularly believed about fat children: that they are fat, unhealthy couch potatoes and getting too little exercise because they’re spending hours plopped in front of the television and playing computer games. What we believe to be true can prevent us — even healthcare professionals who work with children — from looking at the evidence carefully and misguide us to support interventions that aren’t grounded in facts.

Sadly, preconceived beliefs can also lead us to reinforce stereotypes of fat children that contribute to their hurtful ostracization and discrimination.

The evidence can take some digging to find, however, because anything that contradicts popular wisdoms — and more importantly, the premises behind hundreds of millions of dollars being spent on programs to address childhood “obesity” — gets especially little notice and has become buried in spin. Take the study in this month’s issue of Pediatrics.

Boston researchers followed more than 10,000 teens for four years, gathering detailed information on their weekly physical activity. They found that the amount of time teens spend watching TV has no relationship to their levels of physical activity. The researchers explained that sedentary activities and physical activity are not opposites. In fact, as television hours have increased, so have the kids’ involvement in physical activity, with no differences between the boys and girls or their ages.

The results of a NSW Health report were quietly revealed in Australia media today. It found that “children are more active today than they were in 1997, while the incidence of overweight and obese children continues to climb.”

Today’s kids are bigger and more active.

Media and vested interests are scrambling to explain or negate these studies. They can’t, however, because these studies actually concur with the body of evidence. There is little empirical support for the idea that reduced physical activity or increased television and computer time are responsible for childhood “obesity.”

Multiple reviews of the evidence have found no credible grounds for the belief that sedentary habits and inactivity cause the development of “obesity,” that increasing physical activity prevents or reverses weight gain, or that what a child weighs enables us to know anything about his/her activity level or fitness. Varying activity levels are also seen at all varieties of weights. (Extreme examples do not make a truism.) Some of that research was reviewed in a recent post on Digital Age Fears.

Despite all of the opinionating about an “obesogenic environment” causing an epidemic of “obesity” in children, the actual evidence doesn’t support such beliefs and judgements. For example, a review of the data on changes in children’s lives was done by Dr. Roland Sturm, Ph.D. in a 2005 CDC study. He found that active transport, as in walking or biking for transportation or to-and-from school, is not a major source of activity for young people and that there has been little change over the past several decades. In fact, since 1977, children are bicycling nearly three times more and their walking trips have increased from 12% to just over 13%.

Percentage of U.S. high school students who exercised or participated in physical activities that made them sweat and breathe hard for at least 20 minutes on three or more of past seven days. Data from the Youth Risk Behavioral Surveillance System, Centers for Disease Control and Prevention

Dr. Strum also said: “For adolescents, there was no clear trend in physical education during the past decade. For younger children, time spent in organized sports and outdoor activities increased by 73 minutes per week between 1981 and 1997.”

Percentage of U.S. high school students who attended physical education class one or more days during an average school week. Data from the Youth Risk Behavioral Surveillance System, Centers for Disease Control and Prevention

As part of healthy school programs to curb childhood obesity, calls are growing louder for increasing school PE, along with claims that children today aren’t getting enough physical activity in PE class and that schools are “failing our kids.” But these beliefs disregard the fact that for decades the average gym class time devoted to moderate-vigorous physical activity haven’t met national health objectives. A study in a 1993 issue of the American Journal of Public Health, for instance, found that children were aerobically active in the average gym class for a mere 8.5% of class time...about 3.5 minutes. There is nothing new here. Structured exercise has never been a notable source of energy expenditure for children and no program targeting increased activity for children has been able to demonstrate effectiveness in reducing obesity.

None of this is surprising given the fact that the natural diversity in children’s sizes is not determined by calories consumed or burned. In one of the largest and most comprehensive reviews of the research on childhood obesity, the American Heart Association’s 1996 Science and Professionals Scientific Statement, Understanding Obesity in Youth, stated that the association between sedentary activities (such as watching television) or lower resting metabolic rates and “obesity” have not been consistently demonstrated.

This expert review found no differences between fat and lean children in energy expenditure. They pointed out that in studies suggesting that energy expenditure is lower in fat children, energy expenditure was actually similar to slender when indexed to lean body mass. “Obese persons may be socially stigmatized by their leaner peers; this may lead to less participation in athletic activities but may not translate into dramatic differences in daily energy expenditure,” they stated. Observations that fat children are less inclined to participate in organized sports does not mean that it is the cause for their fatness.

The political momentum to address “the alarming rise” of childhood obesity is unlikely to stop and examine the evidence or its own prejudices. Even every cartoon character and favorite child icon has been employed to address “the crisis” and tell kids they need to exercise. Similarly, children’s programming is filled with examples of fat children being mocked and labeled as unhealthy.

As the Federal Communications Commission gets ready to hold the first meeting of its “Media and Childhood Obesity” task force next week, for example, the agenda has already been set: Get fat kids off the couch and more physically active.

At the heart of 'couch potato-ism' is a moral judgement, that today's children are more likely to choose to watch TV than be physically active because they are, by nature, weak willed and lazy. Yes, children today are surrounded by an array of new and exciting forms of technology, but they have not, as a group, become morally degenerate overnight....we need to be cautious about where we lay blame rather than pointing the finger at easy scapegoats. — Michael Gard, senior lecturer of physical education at Charles Sturt University-Bathurst, Australia

© 2007 Sandy Szwarc

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