Yesterday an Institute of Medicine committee released a report on food marketing and children that called for congressional acton "if voluntary efforts by industry fail to successfully shift the emphasis of television advertising during children's programming away from high-calorie, low-nutrient products to healthier fare." According to The New York Times, the IOM report "links TV ads and childhood obesity." According to The Washington Post, it says "TV ads entice kids to overeat." (An earlier Post headline said the report "charges junk food advertising leads to increased obesity in kids.") Yet according to the report, "the current evidence is not sufficient to arrive at any finding about a causal relationship from television advertising to adiposity."
The committee did find "strong evidence" that TV ads influence the "food and beverage preferences," "purchase requests," and "short-term consumption" of children between the ages of 2 and 11. I have no doubt that TV ads have an impact on the products kids request; if they didn't, what would be the point? But the important question for those concerned about weight trends among children is whether advertising has increased their overall calorie consumption. The problem for those who believe it has is that neither "high-calorie, low-nutrient products" nor ads for them are new. Indeed, as George Mason University law professor Todd Zywicki (formerly head of the Federal Trade Commission's Office of Policy Planning) argues, there is reason to believe kids see fewer of these ads nowadays than they did when they were thinner. It is therefore hard to see how advertising can account for the dramatic increase during the last couple of decades in the share of children and teenagers who are overweight.
The issue of causation is also complicated by what the IOM committee calls "mediators"–factors "through which causal influence passes." The particular mediators I have in mind are known as "parents." If TV ads magically and instantaneously deposited fat in children's guts (and if the ads were unavoidable), there would be a strong argument for the sort of legal restrictions the report suggests. But the ads work mainly by stimulating kids to ask for certain products, and parents always have the power to say no. Not only that, but they have a great deal of control over whether and to what extent their kids are exposed to the ads in the first place (especially when their kids are at their most impressionable). The argument for censorship, then, comes down to rescuing children from their parents' laxness.