A report this week from the Institute of Medicine made the front pages of many newspapers and was reported extensively on television. Based on its examination of numerous studies of possible links between TV watching and weight gain, the report attributed a significant part of the increasing obesity among teenagers and young children to television advertising of foods and drinks with high sugar and fat content. It recommended that companies work with scientists and others to reformulate their products and ads. Some persons at the Institute of Medicine went further and raised the prospect of possible Congressional regulation of TV ads oriented toward children, even though, as we will see, the evidence provided by the report is weak and not persuasive.
Before examining this evidence, obesity of children should be placed in perspective. Obesity has increased for most of the past twenty -five years among all groups and at all ages, including the elderly. Presumably, advertising of goods like Big Macs and Coke Cola has less influence over the consumption of adults, particularly that of older men and women. Moreover, obesity has grown in all developed countries, even those with much sharper controls over advertising.
Obesity in the United States and elsewhere started increasing particularly rapidly in the early 1980's. Studies by economists, especially those by Richard Posner and Tomas Philipson, Jesse Shapiro, David Cutler, and Edward Glaeser, and Fernando Wilson sifted through many factors that might be responsible for this accelerated trend toward greater obesity. The two most important factors highlighted by these studies is the lower effective price of fat due to the development of efficient fast food outlets that save on time, and for teenagers a more sedentary use of leisure time due to the growth in time spent with computers, browsing the internet, and playing video games.
There is no doubt that McDonald's and other companies tend to increase their revenues when they raise advertising budgets-otherwise, companies would not be spending as much on advertising. But most of the increase in sales to a company when it advertises more tends to come at the expense of sales by competitors. So if Wendy's raises its advertising, sales by McDonalds and other competitors would tend to fall. To the extent that advertising mainly redistributes customers among competitors, the elimination of advertising of fast foods or sugary beverages through regulation would have relatively little effect on the overall demand for these products.
As far as I could tell from examining the complex report by the Institute of Medicine, it did not include any studies (presumably because none are available) that directly looks at the effects of advertising by fast food and beverage companies on the overall consumption of these goods by teenagers and younger children. Instead, virtually all the studies available to them examine the effects on children's weight of greater or lesser exposure to television.
The problem with such studies, even in the very few that are carefully designed, is that they cannot separate the effect on weight of greater exposure to advertising through watching more television from the effect on the propensity to gain weight from other activities correlated with watching TV, such as more sedentary behavior, or eating popcorn and other snacks while watching. The authors of the report recognize this serious shortcoming in a section on "Recommendations for Future Research", where they say "Even within the domain of television, most of the research that relates television viewing to diet and to diet-related health does not distinguish exposure to food and beverage advertising from exposure to television in general. This lack of relevant research severely constrains the findings that can be drawn about the influence of food and beverage marketing on the diet and diet-related health of American children and youth".
A PhD study in progress by Fernando Wilson at the University of Chicago suggests that this qualification is crucial. He shows that the big increase since 1980 in children's use of time was not toward greater television viewing, for this remained rather constant during the past 25 years-and maybe has declined slightly. What increased by a lot was time spent with computers and videos games at the expense of lesser time spent at sports and other more active activities. Since advertising on computers and video games has been far less important than advertising on television, it is hard to see how the growth in obesity during the past 25 years could be explained at all by advertising toward children, unless TV advertising became much more effective than it had been.
Advertisements clearly influence the demand for different goods, but they also are sensitive to the desires of consumers, including the influence of parents over what is consumed by their children. At the same time that consumers have been gaining a lot of weight, they have become more conscious about eating oats and other high fiber foods, about the vitamins added to different cereals, about the sugar content of foods and beverages, and eating other healthy foods. A study a few years ago by Pauline Ippolito and colleagues at the Federal Trade Commission found that when some parents began to want healthier cereals for their children, companies were quick to respond with new and healthier cereal brands. As soon as they were allowed to do so, they also began to advertise the healthy advantages of oat cereals and other products with high fiber content or with many vitamin supplements.
If children nowadays are heavier because they are less physically active than they used to be, or because their parents find fast food cheap and convenient, it is difficult to see how advertising by food and beverage companies are to blame. And despite the hype the study received, the Institute of Medicine's report on obesity and advertising did not present any convincing evidence that television advertising oriented toward children has been responsible for the increase in children's obesity during the past quarter century.