THURSDAY, Dec. 15, 2011 (HealthDay News) -- In what might serve as a hopeful sign for all children in the United States, a new study finds that obesity rates among New York City's school children have dropped slightly in the past five years, particularly among the youngest.
Although the absolute decline in the obesity rate is only 1.2 percent, it's still the largest drop seen yet in any major U.S. city, the researchers noted, and many of the programs that New York City health and education officials implemented to combat rising childhood obesity rates are being tried in other parts of the country.
"This is really good news, but there are still one in five children in grades K-8 who are obese, which is still a huge number of children," said study author Magdalena Berger, a city research scientist in the New York City Department of Health and Mental Hygiene. "We are on the right track, but we still have a very long way to go."
Obesity among children has been increasing since the 1970s, Berger said. "In the last decade, nationally, we have seen a leveling off of obesity, but this is the first well-documented decline in obesity among children that we have seen."
The drop in obesity is statistically significant, because of the large number of children in New York City's public schools, Berger said. "Whether or not it's actually meaningful is another question," she added.
"I think it's meaningful in the sense that it's not going up, and that's good news, it's not staying stable, and that's good news," Berger said. "I would characterize this as a slow sustained drop over five years; it's not a dramatic drop."
Although the reasons for the decline in obesity among these school children isn't clear, Berger speculated that policies implemented by the New York City departments of health and education, along with more public awareness of the problem, may have played a role.
Study co-author Cathy Nonas, director of Physical Activity and Nutrition Programs in New York City's Department of Health and Mental Hygiene, said several changes in city schools probably contributed to the drop in obesity rates.
"There are significant changes in school food," she said. "There is no whole milk in the schools anymore, it's only 1 percent and the chocolate milk is skim and low sugar," she said. "That saved 4.5 billion calories, just by making that change."
In addition, food served in schools has reduced fat and no trans fats and reduced salt, and the level of fiber has been increased, Nonas said. Drinks and snack foods sold in schools are also healthier, she said. Similar policies were also instituted in early child-care centers, she added.
Also, the city has trained K-5 teachers on how to increase physical activity in the classroom, Nonas said.
"It's a layering effect" that all contributed to reducing obesity rates, Nonas believes. These and similar policies are being implemented throughout the country, she noted.
The report was published in the Dec. 16 issue of the U.S. Centers for Diseases Control and Prevention's Morbidity and Mortality Weekly Report.
For the study, Berger's team used data on the more than 900,000 children in kindergarten to eighth grade in New York City public schools. The city's school system collects fitness data on these students every year, Berger said.
The researchers found the obesity for these children, aged 5 through 14, dropped from 21.9 percent in 2006-07 to 20.7 percent in 2010-11, a little more than a 1 percent decline among kids overall.
The biggest drop was among children aged 5 to 6, from 20.2 percent in 2006-07 to 18.2 percent in 2010-11, they noted.
These declines in obesity were seen in all race and ethnic groups, the researchers added.
Obesity expert Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine, said that "this report, showing a decline in obesity among New York City school children over the past five years is, to be sure, a glass half full. But I wouldn't get carried away with the celebrations just yet."
The absolute decline in the overall obesity rate is roughly 1 percent in five years, he noted. "At that rate of progress, it would take a century to fully reverse the damage done over the past several decades. The rate of obesity is still over 20 percent, and the gains are uneven."
This is a window to a very small part of a nationwide obesity problem, Katz added. "The resources of New York City may be sufficient to produce some good news, but that is not generalizable. We have a long way to go, and will need to build diligently on these modest gains to get there," he said.
"Obesity is still a major health issue in children," Dr. Achiau Ludomirsky, chief of pediatric cardiology at NYU Langone Medical Center, New York City, added in a statement. "We can definitely see that the decline in obesity among [New York City] school children is the result of early intervention for better diet, opportunity for physical fitness and the education of students and parents. It is a three-tier effect."
What kids eat and learn away from school is also key. "We can't reduce obesity levels without working closely with the families of students to help them offer better diet options at home and limit a child's time in front of the television, computers and video games," Ludomirsky said.
"But we still have a long way to go," he stressed. "If we don't address the childhood obesity epidemic more proactively right now, it will become a major health issue for the next generation of Americans."
For more on childhood obesity, visit the U.S. National Library of Medicine.