The problem is that the marketing deals often promote consumption of foods that are a nutritionist's nightmare. Pennsylvania school food-service directors, for example, reported in June that their cafeterias' best sellers were, in rank order: pizza, hamburgers and sandwiches; cookies, crackers, cakes and pastries; French fries; potato chips and cheese puffs; and sodas and sugary sports drinks.
Since, according to the institute's study, 40 percent of children's daily food intake occurs while they're at school, schools are implicated in a worrisome trend: Obesity has doubled among teens and tripled for children ages 6 to 11 since the 1970s, according to the Institute of Medicine's study, Preventing Childhood Obesity, released Sept. 30.
That's no surprise to Diana Frey, a junior at Montgomery-Blair High in Silver Spring, Md. "A lot of kids don't even have time for breakfast," then eat a bad lunch at school, she said.
But Montgomery-Blair is in a bind, principal Phillip Gainous said. It signed an exclusive marketing deal with Pepsi in 1997, which pays the school $55,000 a year. The contract comes up for renewal soon, and the Montgomery County school system recently issued guidelines aimed at improving nutrition. Out went the soft drinks in Montgomery-Blair's vending machines. In came fruit juices, chocolate milk and water. Pepsi's vending-machine revenue has plummeted, according to Gainous. Pepsi might not renew the deal.
"The money is absolutely vital to the operation of the school," said Gainous, who has used it to buy computers and subsidize fees for SAT, achievement and Advanced Placement tests for low-income students.
"How are my kids from poorer areas supposed to compete with affluent kids without this money? If I push them to take these tests to get into college," he said, "I have to be prepared to pay for them."
Other schools have switched with better results. North Community High School in Minneapolis found that it made $4,000 a year more selling water in its vending machines than it did selling soft drinks.
The biggest experiment is under way in California, where coalitions of parents, students and pro-nutrition groups won a statewide ban on soft drinks in elementary and middle schools, which went into effect in July.
"We know that children learn from what we tell them, but we need to remember they also learn from what we sell them," said Harold Goldstein, executive director for the ban's leading promoter, the California Center for Public Health Advocacy.
Soft-drink companies maintain that banning products is not an effective strategy for curbing obesity.
"We need to teach people how to make their own choices, and you don't teach people things just by restricting them," said Kathleen Dezio, a spokeswoman for the American Beverage Association in Washington.
Contact reporter Camille Ricketts at 202-383-6020 or firstname.lastname@example.org.