Obesity among young children fell to 8.1 percent in 2011 to 2012, from 14 percent in 2003-2004, a the study published today in the Journal of the American Medical Association found. The results, by researchers at the Atlanta-based Centers for Disease Control and Prevention, expands on information initially reported by the federal agency in October.

About 78 million adults are obese, or about one-third of the population, according to the CDC. While rates for teenagers and adults have largely remained the same over the last decade, according to the report, the progress seen among the very young offers hope for the future, said Risa Lavizzo-Mourey, head of the Robert Wood Johnson Foundation.

"Progress among the youngest children is especially important because we know that preventing obesity at an early age helps young people maintain a healthy weight into adulthood," said Lavizzo-Mourey, whose nonprofit group has pledged $500 million to reduce childhood obesity in the U.S.