In 1966, the Child Nutrition Act shifted control of the school lunch program from a number of government agencies to one, the USDA. In the decades since then, childhood weight gain has become a major concern of health experts, as the percentage of children who are overweight has been increasing. According to the Centers for Disease Control and Prevention (CDC), for instance, the percentage of overweight children between the ages of six and 11 in 2003-04 was more than double that of the late 1970s. As the number of overweight and obese students increased, the focus of school nutrition shifted from its original concern—making sure that students had enough to eat—to its more recent preoccupation with preventing weight gain. In 1994, President Bill Clinton (1993-2001) signed the Child Nutrition Reauthorization Bill, which required schools to set limits on the fat content of school lunches. According to a 2001 USDA report, lunches became significantly healthier in the years after the law passed. However, the report also found that, besides lunches, less-healthy competitive foods were available in many schools, and that those options sometimes provided an incentive for students to skip school lunch altogether. Competitive foods have presented an obstacle to the USDA's regulation of food in schools. In 1983, a federal court overturned a USDA regulation that had prohibited the sale of junk food in schools from the beginning of the school day until the end of the last meal period. The court ruled that the USDA could ban junk food in cafeterias only during mealtimes. The USDA does place some restrictions on competitive foods, requiring them to contain at least 5 percent of the recommended daily allowance of a number of specific nutrients, including protein and certain vitamins. But those restrictions have drawn criticism for not limiting foods with ingredients that can be unhealthy, such as sugar, fat, and salt, or those exceeding a certain number of calories. As a result, schools cannot sell chewing gum or breath mints, for instance, because they do not contain the required nutrients, but can sell candy bars and french fries, because they do—even though they also contain large amounts of sugar and fat, respectively. Studies have shown a positive correlation between school meal programs and increased food security. Among low-income children, the marginal food insecurity rate of those with access to the School Breakfast Program is lower than that of those children without access to the program. This increase in food security has not been shown to have significant long-term health benefits, but it does have a positive impact on education. Subsidized lunches appear to encourage children to attend school, and to free up food at home for other family members to consume.