By Barbara Mantel, NBC News contributor
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.
“The best way to deal with many health problems, as with obesity, is prevention,” said Frieden. “That’s why we are so encouraged to see these decreases, even though they are small, in this age group.”
“But the prevalence is still high, and so there is still a lot of work to be done,” CDC epidemiologist and lead author Ashleigh May told NBC News.
In contrast, between 2003 and 2008, just nine states showed a significant decline in obesity among low-income preschoolers, 11 had no change, and 24 had a significant increase.
“We are starting to see some progress in reducing the prevalence of obesity among children,” says CDC epidemiologist and lead author Ashleigh May. “But the prevalence is still high, and so there is still a lot of work to be done."
There was wide variation in obesity rates across states in 2011. Hawaii’s 9.2 percent obesity rate for this group of young children was the lowest. California’s 16.8 percent was the highest.
New Jersey, which showed improvement, still has a relatively high rate of obesity among low-income preschoolers of 16.6 percent. In comparison, Colorado, though losing some ground, has a relatively low obesity rate of 10 percent.
“Each state has different populations and different initiatives,” says May, making it difficult to generalize why some states have higher obesity rates than others.
For example, health officials in Michigan -- where 13.2 percent of low-income preschoolers were obese in 2011 compared to 13.9 percent in 2008 -- credit the slight improvement, in part, to a national intervention called the Nutrition and Physical Activity Self-Assessment for Child Care (NAP SACC). Since 2009, the program has reached nearly 100 child care centers serving low-income families in Michigan and more than 7,000 preschoolers in the state.
“Child care centers are an ideal place to work on obesity prevention efforts,” says Lonias Gilmore, a public health consultant with the Michigan Department of Community Health. These young children “receive most of their nutrition and opportunities for physical activity in these settings.”
The program has led to increased physical activity, a reduction in salty and sweet snacks, and greater availability of water and lower fat milk at centers. Michigan officials hope to expand the program state-wide.
Nationally, 1 in 8 preschoolers, regardless of income, are obese, according to government statistics. That breaks down to 1 in 5 black preschoolers, one in 6 Hispanic preschoolers, and 1 in 11 non-Hispanic white preschoolers.
To bring those rates down, the CDC recommends that doctors routinely measure children’s body mass index and counsel parents about physical activity and nutrition. Parents are advised to serve nutritious foods, make water easily available and limit TV time. And the agency calls on state and local governments to help local schools open gyms, playgrounds and sports fields during non-school hours, to provide access to free drinking water in parks, child care centers and schools, and to make it easier for families to buy healthy, affordable foods.
“Every community can work to make the healthy choice the easy choice so that our nation’s children grow up and thrive,” according to Frieden in an online video.
NBC News Channel producer Erin Sykes contributed to this report