According to the first nationwide study on the effects of banning junk food sales at schools, recently published in the journal Pediatrics, there is a correlation between such bans and declining weight gain in children, Good Education reports.
Researchers studied data from 6,300 students in 40 states, measuring each student's weight and height in 2004, upon entering middle school, and again in 2007. They also looked at which children lived in states with anti-junk food laws. Children that lived in states with strong laws banning junk food sales at school gained less weight between fifth and eighth grades than those living in states with weak or nonexistent junk food laws. Furthermore, overweight and obese children were more likely to reach a healthy weight by eighth grade if they lived in anti-junk food states.
According to Good, the differences were not terribly dramatic. They also did not discuss how or if such laws affected younger children or older teens or whether there were other variables that may have been in play. Some states, for example, have much higher obesity rates than others. Since obesity tends to be higher in lower income communities, the results of the study might have been skewed or influenced by the poverty differential between states.