Health officials say they have the first evidence of a national decline in childhood obesity.
A government report released Tuesday found at least slight declines in obesity rates for low-income preschoolers in 18 states. Rates went up in three states.
The report is based on the heights and weights of children in a federal food program.
Previous research suggested national childhood obesity rates were flat, though some cities have reported improvements. Nationwide, about 12 percent of boys and girls are obese.
The report didn't answer why some states improved while most others held steady. Experts credit policies that promote breast-feeding and healthier eating.
Overweight or obese preschoolers are five times more likely than other children to be heavy adults.