Obesity rates among preschoolers from lower-income families declined in Massachusetts and 17 other states from 2008 to 2011, according to a government report released Tuesday that showed that efforts to keep children’s weight in check are starting to take hold across the country.
While the decreases in most states were slight, a decline in this group gives health officials reason for optimism because obesity has soared faster over the past two decades among children from poorer families than those from more affluent communities.
One in eight preschoolers in the United States is obese. Among low-income children it is one in seven.
“Although obesity remains epidemic, the tide has begun to turn for some kids,” said Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention, which released the report. “While the changes are small, for the first time in a generation they are going in the right direction.”
In Massachusetts, obesity rates among low-income preschoolers fell less than one-half a percentage point, from 16.7 percent of preschoolers to 16.4 percent. Florida, New Jersey, and three other states as well as the US Virgin Islands had at least a 1 percent drop in their obesity rates, while 20 states saw no decline. Three states — Colorado, Pennsylvania, and Tennessee — had an increase.
The report examined height and weight data from 11.6 million low-income children who were 2 to 4 years old and participated in federally funded nutrition programs. They came from 40 states, the District of Columbia, Puerto Rico, and the US Virgin Islands.
Researchers last analyzed the data in 2009, when only nine states had obesity declines and 24 had increases.
“This is really broad. Until now it’s been a patchwork,” Heidi Blanck, a CDC researcher who is an author of the report, said of the recent declines. “We really think this is how we’re going to curb the epidemic, by getting really young children.”
Preschoolers who are overweight or obese are five times more likely to be overweight or obese as adults, creating a higher risk of heart disease, stroke, diabetes, and cancer.
The reasons for the declines are unclear. Blanck offered several theories. Children consume fewer calories from sugary beverages than in 1999, she said. And more women are breastfeeding, which often leads to healthier weight gain for young children.
The CDC also cited state programs that encourage kids to be more active and eat more nutritious foods with fewer calories.
Researchers at the Harvard Pilgrim Health Care Institute documented a declining obesity trend among Massachusetts preschoolers last year from all income levels.
They found that the percentage of obese girls under age 6 dropped from 9 percent to slightly more than 6 percent from 2004 to 2008; the percentage of obese boys under age 6 fell from nearly 11 percent to just under 9 percent.
The study last year also found that those on Medicaid — which serves lower-income people — had much higher obesity rates and a much smaller decline in these rates, less than 1 percent, over the period.
Other recent data collected by the state have shown giant disparities in childhood obesity prevalence in different Massachusetts communities.