You know those unpopular laws regulating junk food and sugary drink sales in schools? The ones your children wouldn’t stop complaining about? Well it turns out they may actually be effective in slowing the rate of childhood obesity, according to a national study released Monday.

The study, published in the journal Pediatrics, analyzed data from 6,300 students in 40 states who participated in the Early Childhood Longitudinal Study. The heights and weights of fifth graders entering middle school were measured in spring 2004, at the start of the study, and again in 2007, during the spring of their eighth grade year.

Databases of state laws on school nutrition during this period were also assessed, but the study did not identify the states due to a data license restriction to protect student confidentiality.

The laws regulate food and beverages available for purchase in public school vending machines, cafeterias, and stores (known as “competitive foods” because they compete with meal programs), beyond breakfast and lunch times. The Healthy Hunger-Free Kids Act of 2010 tasked the U.S. Department of Agriculture (USDA) with updating the standards for these “competitive foods” to align them with federal dietary guidelines, but the USDA has not yet accomplished this.

Laws that outlined specific, required nutrition standards such as limits on salt, sugar, or fat content were identified as “strong.” By contrast, “weak” laws were those that used terminology such as “recommended” or “healthy foods” but lacked specific guidelines. At the time of the study, 27 of the 40 states studied had no laws relating to middle-school students, 7 had weak laws and 6 had strong laws.

Results showed that children who lived in states with strong laws regulating school snacks gained less weight from fifth to eighth grade when compared to those living in states with no laws regulating school snacks. For example, students in strong law states who were five feet tall and weighed 100 lbs. gained about 2.2 fewer pounds over the three year period.

“Strong-law” states were also correlated with weight loss, with overweight and obese fifth graders more likely to reach a healthy weight by eighth grade. Nearly 39 percent of fifth-graders in “strong-law” states were overweight when the study began, but the number declined to about 34 percent by eighth grade. Obese fifth-graders also made up about 21 percent of students, but this figure declined to about 18 percent in eighth grade.

In states with no relevant laws, about 37 percent of fifth-graders were overweight and 21 percent were obese, and those numbers remained nearly the same over the three-year period.

Lead study author Daniel Taber, a researcher at the University of Illinois in Chicago stated, “This study definitely suggests that states can have an impact on student health when they enact effective school health policies.”

The Bottom Line

While the study does not draw the dramatic conclusions some may have hoped for, the results do raise hope that removing junk food from schools will elicit positive change. With nearly a quarter of all elementary school students and about 20 percent of adolescents classified as obese, it’s undeniable that positive change is necessary.

“Nanny-state” concerns and politics aside, the truth of the matter is that obesity is a real and growing epidemic that affects our youth and follows them far into adulthood. A step in the right direction is to change the environment from obesogenic to health-promoting.

While limiting access to unhealthy foods is a means to an end, it is crucial that we teach our children how to make healthful and wise decisions when they are on their own and have access to an excess of junk foods. Increasing fruit and vegetable intake is especially crucial for this age group.

Teen Diets Severely Lacking in Fruits and Vegetables

Setting guidelines at school and making it a less obesogenic environment is still a good start. Because long-term eating habits develop during our formative years, not having access to junk food and sugary drinks limits exposure and forces adolescents to seek out more healthful alternatives, cultivating good habits instead of bad.