A study published in the CDC journal Preventing Chronic Disease shows that high-school students in the city averaged 1.38 servings of sugar-sweetened beverage per day in 2006. That was down from 1.71 servings a day in 2004, when the ban -- which blocks schools from selling the beverages on campus -- went into effect.

The reduced consumption of the high-calorie drinks translates into about 45 fewer calories a day. Previous studies have shown that the average teenager consumes about 300 calories a day from sugar-sweetened beverages.

"This study shows that a very simple policy change can have a big impact on student behavior," lead author Dr. Angie Cradock, a senior research scientist at the Harvard School of Public Health, said in a written statement released by the Robert Wood Johnson Foundation, which funded the study. "It also shows that when students couldn't get these unhealthy beverages in school, they didn't necessarily buy them elsewhere."

The CDC has been a champion of limiting kids' access to sodas, pointing out that rates of childhood obesity have tripled in recent years as children's consumption of sugar-sweetened beverages has been rising.

If the Boston ban is an example of nanny state policies, "Let's hear a round of applause for the nanny state," Dr. Marion Nestle, professor of nutrition, food studies, and public health at New York University, told CBS News in an email. "Do I think soft drinks should be banned from schools? You bet. Nobody is stopping parents from giving their kids sodas at home, advisable as that might be."

From the August 31, 2011, Prepared Foods' Daily News.