Tougher laws regarding nutrition in schools have been implemented across the country. But are they working?

A new study says yes.

The study found that students who attend schools with tougher laws governing school food, such as prohibiting use of trans fats and getting rid of soda machines, are losing weight. The study, which looked at 6,300 students in 40 states, found that children overweight or obese in fifth grade were more likely to reach a healthy weight in the eighth grade if attending schools with strong nutrition laws.

Children in the study also gained less weight from fifth through eighth grades if they lived in states with strong, consistent laws versus no laws governing snacks available in schools.

In states with weaker laws, the percentage of overweight and obese children remained unchanged between those same grades.

In the study, laws were considered strong if they included specific nutrition requirements, such as limits on sugar and fats. Laws were rated weak if the requirements were vague and merely urged sales of "healthy" food without specifics.

The study took gender, race, income and school location into account.

The authors of the study, which was released online Monday in the journal Pediatrics, concluded that nutrition laws must be implemented across all grades in order to be effective.

Nutrition in school remains a hot-button issue, with some states resisting the notion of a "nanny-state," while many experts point at the rise of obesity in children as an indicator that the status quo cannot continue.