Back in 2013, the U.S. Department of Agriculture released the Smart Snacks in School standards, which aimed to reduce fat and sugar in students’ diets by encouraging schools to provide healthier snacking choices like whole grains, low-fat dairy, fruits, vegetables and leaner protein. The standards were put in place after research indicated that schools which offered foods and beverages containing solid fats and added sugars were helping to add “empty calories” to youngsters’ diets. Consuming empty calories can increase overall energy intake, leading to overweight and other health conditions.

The Smart Snacks guidelines applied to foods sold to students in a vending machine, a school store or any other venue. Practically, this meant offering water instead of soda, for example, and fruit cups instead of candy bars.

To determine the effectiveness of these guidelines, a survey of 1,959 students, ages 6–18, in 310 schools was conducted using 24-hour dietary recall information. Among the 528 students who ate snacks at school, 420 lived in a state with a law requiring schools to follow the guidelines. Writing in JAMA, the authors reported that students living in a state with a law that mandated school compliance with the Smart Snacks guidelines consumed 25.7% of their total daily energy intake (508.7 average kilocalories) from solid fats and added sugars. That percentage was 28.4% (562.5 average kcal) among students in a state without the law. Although the difference seems small, the researchers suggested the results indicated an improvement in diet quality among students who bought food at Smart Snacks schools.