First lady Michelle Obama and Food Network chef Rachel Ray discuss lunches with students from the Eastside and Northside Elementary Schools during a "Let's Move!" program at the Clinton, Miss., schools Wednesday, Feb. 27, 2013. The pair visited with the children and conducted a cooking contest between the schools' chefs. (AP Photo/Rogelio V. Solis)

The fight against childhood obesity is beginning to show results, say government researchers.

After rising for decades and then stabilizing somewhat in the mid-2000s, the obesity rate among low-income preschoolers declined by small but statistically significant amounts in 19 states and U.S. territories between 2008 and 2011, according to a report from the Centers for Disease Control and Prevention released Tuesday.

“We are excited because we have seen so much work going on in the past several years at the local, state, and national level, and we believe these changes are beginning to make a difference,” co-author Heidi Michels Blanck told NBC News.

The government initiatives include First Lady Michele Obama’s Let’s Move campaign to reduce childhood obesity; improvements in the nutritional content of the food provided by the federal government’s Supplemental Nutrition Program for Women, Infants and Children (WIC); and growth in the number of U.S. hospitals enrolled in the World Health Organization’s Baby Friendly Hospital Initiative, which encourages new moms to breastfeed.

“We know that breastfeeding leads to healthy weight in the first year,” said Blanck, chief of the CDC’s obesity prevention and control branch.

Still, there is no proof that specific government interventions have led to the declines in obesity noted in today’s report, acknowledged CDC director Dr. Tom Frieden in a media conference call.

Government researchers analyzed measured height and weight for 11.6 million preschoolers aged 2 to 4 years who participate in federally funded nutrition programs. States and territories report that data to the Pediatric Nutrition Surveillance System. The researchers included data from 40 states, the District of Columbia, the U.S. Virgin Islands and Puerto Rico and excluded others that did not report data consistently or changed their methods of collection and reporting.

Children with a body mass index in the 95th percentile or greater for their age and sex were categorized as obese.

Obese preschoolers are more likely than normal-weight children to be obese adolescents and are five times as likely to be obese as adults, according to the CDC. Obesity is associated with high cholesterol, high blood sugar, asthma, and mental health problems.

“It is important for us to look at this age group in that demographic,” says Dr. Lindy Christine Fenlason, director of Vanderbilt University’s Pediatric Weight Management Clinic. “With financial barriers, you run into limited access to healthy foods, limited places for safe physical activity” and sometimes limited educational resources about good nutrition, says Fenlason.

Six of the 19 states and territories showing progress — Florida, Georgia, Missouri, New Jersey, South Dakota and the U.S. Virgin Islands — had at least a one percentage point decrease in the obesity rates. Twenty-one states had no significant change, while three states — Colorado, Pennsylvania, and Tennessee — saw an increase.

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