No kidding, McDonald's Happy Meal fans in the San Francisco area might have to look elsewhere if they want movie tie-in trinkets, along with their fries and burgers.

On November 3, San Francisco's Board of Supervisors gave preliminary approval for a ban on unhealthy restaurant meals that include toys as enticement for children to consume their products—the so-called "Happy Meal ban," named after the popular McDonald's menu item. The ban dictates that a restaurant cannot provide an incentive item (a trading card, game or other prize) for a menu item that has more than 200 calories or for a meal that tops 600 calories. The law would also prohibit menu items from being sold as children's meals if they contain excessive fat or sodium as well as require that the fare includes at least a half cup of fruit and at least a three-quarter cup of vegetables (pdf).

The ban's proponents see it as a modest victory in efforts to curb childhood obesity, citing the 2007 California Health Interview Survey that found 15 percent of 12-to-17-year-olds in the greater Bay Area to be overweight or obese (8 percent of children under age 12 were found to be overweight for their age). Opponents for the most part see the measure as government interference in parenting. Mayor Gavin Newsom indicated a desire to veto the ban, although the board is expected to formally approve the measure in a final reading November 9 and has enough votes to override a mayoral veto.

San Francisco's actions coincide with a Harvard University study published this week in the journal PLoS Computational Biology, which modeled obesity as a kind of infection, spreading in part because of social contact. It found that the number of obese Americans will not plateau until it reaches 42 percent of adults (the rate has been about 34 percent for the past five years). In a bit of good news–bad news the researchers claim that whereas the U.S. may not reach the 42 percent obesity rate for another 40 years, their projection is a best-case scenario—it could be higher.

Scientific American
interviewed Marion Nestle, a New York University professor of nutrition, food studies and public health, about the significance of such legislative efforts to improve children's eating habits, and the likelihood that they will help keep kids from becoming overweight.

[An edited transcript of the interview follows.]

Based on your study of food sociology, will San Francisco's proposed ban on Happy Meal–type offerings have a big impact on efforts to keep children from becoming overweight?
Let's be clear. Toys in happy meals are about marketing, not health. There is only one reason why they are there: to get kids to pester their parents for the meals. The toys are not about the food—they are about the marketing. With that said, one meal is not going to affect obesity rates. But cooling down the marketing environment might make life a lot easier for parents who want to feed their kids more healthfully.

What is the most significant reason for the rise in children who are overweight or obese?
I can't point to one reason in isolation from the others. Obesity rates started to go up in the early 1980s. What happened then? Farm policies that encouraged greater food production, Wall Street pressures on corporations to grow every quarter, economic downturns that make people work longer hours, societal changes that keep kids indoors rather than outside playing on their own. Food companies responded by putting foods everywhere, encouraging snacking, serving larger portions, making it normal for kids to drink sodas all day long. The list goes on.

If I had to choose one, I'd say it's the rise in caloric availability from 3,200 per capita per day in the early 1980s to the present 3,900 per day today—roughly twice the population's need. Food companies have to sell products in a hugely competitive environment. On top of that, they must demonstrate growth to Wall Street every quarter.

New York City has tried a few different approaches in recent years to discourage unhealthy eating, including a move by the Bloomberg administration to have chain restaurants display calorie information on their menus. The mayor also wants to have soda excluded as an item that can be purchased using food stamps. Is there any evidence that such measures are working (or would work) as intended?
Calorie labeling is soon going national—it's signed into the health reform act—so we will be able to conduct that experiment on a much larger scale quite soon. Preliminary studies do not show much difference in calorie intake, but I don't think the studies are asking the right questions. I know plenty of people who go into calorie shock when they look at a cookie and discover that it contains 670 calories. Some people will change their choices in response to such information, others will not. The studies need to probe such differences.

What I like about calorie labeling is its educational potential. People do not understand calories very well. Labeling will be accompanied by a statement about a 2,000-calorie standard. Eventually, it can encourage people to get a feel for the amount of food that balances their daily needs.

The word "epidemic" is often used when talking about obesity, whether for children or adults. Epidemic, however, implies that there is a contagion involved. Is this a proper characterization of obesity, or does thinking of it in terms of an infectious disease contribute to the problem?
I think plenty of sociologists  would consider obesity "contagious" in the sense that eating habits are exquisitely sensitive to peer pressure and the social context, most of which encourages people to eat more than they might do otherwise.

What is the most effective relationship between government and its citizens when dealing with healthy eating?
I see the government's role as giving the best possible advice—direct, unambiguous, based on available science and free of food industry influence—about the role of diet in health. The government's role should be to make it easier for people to eat more healthfully. The government currently supports the existing food system in multiple ways that promote overeating in general and of less healthful foods in particular.

What kind of changes should the U.S. make, then?
If policies were restructured to link agriculture to public health, fruits and vegetables would be cheaper and more readily available, for example. And the government could put restrictions on food marketing to children to help create a food environment that promotes more healthful eating. As citizens we can vote with our forks for the kind of food system we want, but we also need to exercise our democratic rights and encourage better federal policies.