A study by San Francisco State University has stated that for preventing childhood obesity banning sugary beverages and junk foods at schools was necessary.

Study's first author Emma Sanchez-Vaznaugh, assistant professor of health education at SF State, said, "This is one of the very first comprehensive investigations that examined whether childhood obesity trends changed after new statewide policies were enacted in California."

Governor Shwarzenegger had signed SB 677, SB 965 and SB 12 into law between 2003 and 2005. A complete set of statewide policies that supported sodas and other highly sweetened beverages to be banned in all of California's public schools.

As a part of California's annual Physical Fitnessgram testing, Sanchez-Vaznaugh and colleagues used a data of eight years of body mass index (BMI) of students from fifth and seventh grades.

According to the data overweight students in all groups were increasing before the policies took effect.

This number came down significantly after the policies took shape.

Sanchez-Vaznaugh added, "Although policymakers cannot directly influence student behaviour, our study shows that governmental policies can help define the environment in which children learn to make food choices and thus shape the food behaviours."