(CBS/AP) Childhood obesity rates are falling in New York City, according to a new government study. The CDC's study of public schoolchildren in kindergarten through eighth grade found obesity rates fell from 21.9 to 20.7 percent overall between the 2006-2007 and 2010-2011 school years.
The 1.2 percentage drop was the biggest recorded decline in childhood obesity in a large U.S. city, the CDC said. That means there are about 6,500 fewer obese children in the public schools, according to city officials.
For the study, published in the Dec. 15 issue of the CDC journal Morbidity and Mortality Weekly Report, researchers analyzed body mass index (BMI) data collected by NYC physical education teachers, which were reported to the city's Department of Health. The researchers found that while obesity rates declined for children in all groups, black and Hispanic children lagged. The largest decrease - from 20 percent to 18 percent - was in children ages 5 to 6.
City Health Commissioner Thomas Farley said the report validates public health policies developed under Mayor Michael Bloomberg's administration, aimed at combating the decades-long rise in obesity rates among children.
"This comes after decades of relentless increases," Farley told the New York Times. "What's impressive is the fact that it's falling at all."
He said, however, more needs to be done to reduce rates among low-income and black and Hispanic children. "Unfortunately, the benefits of this were not in the children who needed it the most," Fairley said.
No other city has extensively monitored student weight for the past five years, but Farley said that in recent talks with other cities it appeared that only parts of California were reporting similar - albeit smaller - declines. "Many of them didn't have data," he said.
What did New York City schools do to fight obesity?
City officials implemented changes from 2003 to 2009 that might have contributed to the decline, the report said. Those include regulations to improve nutrition, increased physical activity time, and changes to cafeteria food that included swapping whole milk with 1 percent and skim milk in 2005. School nurses also were trained to identify kids with weight problems and to educate the community, the report said.
But the report's authors said they couldn't definitively prove a cause-and-effect relationship between the fitness intervention and the obesity decline.
Dr. Achiau Ludomirsky, chief of pediatric cardiology at New York University Langone Medical Center, called the report's findings significant.
"It looks like something is working," he said, adding that the combination of public health policies, involvement of nurses and education were likely contributed to the decline. "I think it's pretty encouraging, and we need to put more resources into that."
Is the success in NYC schools a sign of things to come for the rest of the country?
"The resources of New York City may be sufficient to produce some good news, but that is not generalizable," Dr. David L. Katz, obesity researcher and director of the Prevention Research Center at Yale University, told HealthDay. "We have a long way to go, and will need to build diligently on these modest gains to get there."
Said Katz, "I wouldn't get carried away with the celebrations just yet."