While obesity rates among low-income preschoolers in 19 states recently fell, Illinois’ rates didn’t budge.

This was one of the findings of an analysis by the Centers for Disease Control and Prevention released late Tuesday, which was greeted with mixed feelings by local public health experts.

“I think it’s a little disappointing that we haven’t seen more change in Illinois” said Elissa Bassler CEO of the Illinois Public Health Institute, which works to combat obesity in the state. “But it was encouraging to see that many of the factors that seem to be driving the [declines] are the multi-stakeholder approaches that we have been supporting in the state.”

The analysis examined obesity rates among 2 to 4 year olds whose families participate in the Women Infants and Children public assistance program. Between 2008 and 2011 rates of obesity in the children decreased in 19 states including California, Washington, Minnesota, Iowa, Kansas, New Mexico, Mississippi, New York and Florida. In 21 other states, including Illinois, Wisconsin, Indiana and Arizona, rates remained statistically unchanged. And in three states—Colorado, Tennessee and Pennsylvania—obesity rates rose.

On a national level the news was met with cautious hope that this could mark the beginning of a sea change against the childhood obesity that tripled over the last three decades.

“For the first time we are seeing a large number of states showing a decline after years of increases,” said Ashleigh May an epidemiologist at the CDC and the lead author on the study. “So this seems to indicate that we may be seeing a real changing of the tide.”

Dr. Adam Becker, who serves at the executive director of the Consortium to Lower Obesity in Chicago Children (CLOCC) shares May’s optimism for but wishes Illinois had fared better.

“For the  nation it’s great news that we are seeing these downturns for the lowest income kids where you have significant obesity prevalence,” he said. “But for Illinois it’s a mixed bag. We would have liked to see Illinois on the list of states where the numbers are going down. Still, for years you have seen this meteoric rise in childhood obesity rates  and so this would suggest that we may be nearing the end, plateauing or entering a real downturn. “

While this CDC examination of select preschoolers showed no improvements for Illinois, Becker notes that CLOCC’s analysis of obesity data for Chicago Public Schools and local Catholic schools between 2003 and 2008 indicated declining rates among kindergarteners. The figures show rates dropping from 24 percent in 2003 to 22 percent in 2008. A recent Chicago Department of Public Health analysis looking at CPS numbers only indicated a further drop among kindergarteners to 20 percent in 2011.

An analysis using the same somewhat imperfect mix of CLOCC and CDPH data would, however, also indicate that obesity among CPS sixth graders may be rising— from 28 percent in 2008 to 29.2 percent in 2011. Hispanic male sixth graders suffered the highest levels at 39.8 percent.

Additionally, CLOCC data indicates that obesity rates among Chicago students check in at about 1.5 to 2 times the national average for children of similar ages.

Why are Chicago kids so much heavier than most of their counterparts across the nation? That’s a question Becker has been chewing on for several years.

“I wish I knew the answer,” he said.

“We have done a couple of things to try to tease that out. We’ve looked at food deserts,  crime and environments that lead to a lack of physical activity. But other urban centers like New York and LA have those same issues and their obesity numbers are not as high as ours.  Others say it’s because of our climate which makes it hard to be out and active for about half of the year, but New York is pretty cold too.  Others have suggested that because Illinois is just north of the Southern Gulf States [with high obesity rates] that it’s a product of that direct migration. But pinning this down is very hard,” Becker said.

“It’s a perplexing issue and I wish that we could pinpoint exactly what it is so that we could do that one thing or that collection of things but even the CDC says it is not sure what exactly what factors drive this change.”

So the public health community is moving forward with a multiple approaches, many of which mirror practices in states that showed obesity declines in the latest study.

Among them, Becker notes, are new licensing requirements (already enacted in Chicago) for state child-care facilities that would limit access to sugar sweetened beverages, increase physical activity and reduce exposure to food marketing through screen time. 

He says provisions for the new guidelines are still in the hands of a joint committee of the Illinois General Assembly and are expected to come out “any Friday now.”

While May is pleased with the declining obesity rates in so many states, she warns that they don’t mean it’s time to break open a Twinkie and call it a day.

“The national prevalence for childhood obesity is still much too high,” she says, “We are not out of the woods yet and there is still a lot of work to be done.”

Still, she says, that Illinoisans shouldn’t fret too much over their static rates. 

“ I would say that no change is a good thing—at least you’re not increasing,” she says, “Obesity did not become a public health crisis overnight and so we are not going to be able to reverse it overnight. It’s going to take multiple years and multiple changes on multiple levels to change things for good.”

So will Illinois make the list of states that sees a decline next year?

“I’m feeling optimistic,” says Becker of CLOCC, “so let’s say ‘yes’.”

Monica Eng is a producer for WBEZ. Follow her @MonicaEng