There have been a few signs recently that obesity might not develop into the spectacular public-health crisis it seemed destined to become. It might just remain a huge public-health crisis.

The Centers for Disease Control and Prevention (CDC) reported this month that the obesity rate dropped among younger, poor children in 19 states and territories between 2008 and 2011. The rate remained the same in 19 other states and in the District and Puerto Rico. Only three states saw increases. (Not enough data were collected in 10 states.)

Public-health advocates have worried for years that the United States was entering an age of obesity, with the American waistline inexorably expanding and, with it, the prevalence of diabetes, heart conditions, joint trouble, even cancer. Now it seems the country may be reaching a plateau, even among at-risk children.

Last year, health economists estimated that keeping the national obesity rate where it is would avoid $550 billion in extra health spending over the next two decades. But the country must do better than simply stand still.

Medical costs related to adult obesity already cost the nation about $150 billion a year, not to mention loads of unquantifiable suffering. One in eight young children remains obese, and the numbers are worse among African-Americans and Hispanics. Very often, the weight stays on.

The CDC could not pinpoint a trend or a policy that made the difference over the past few years; that will take a lot more research. But Laurence Grummer-Strawn, chief of the nutrition branch in the CDC’s Division of Nutrition, Physical Activity and Obesity said that the agency could offer its “best guess.”

The federal Women, Infant and Children (WIC) program, which offers food vouchers to poor families, changed the way it distributes its benefits to encourage the buying of fresh fruit rather than sugary fruit juice and of low-fat milk rather than whole milk. The CDC also points out that more mothers are breast-feeding, which might help, and that public education and outreach have ticked up.