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.