Children between 2 and 5 are a small fraction of the population, only about 6 percent, according to the 2010 census. But the impact of new findings by the Centers for Disease Control and Prevention, regarding the health of that age cohort, is very big indeed.

To the surprise and delight of CDC researchers, the obesity rate for kids in the 2-to-5 age group declined by a whopping 43 percent over the last decade, from 14 percent to about 8 percent.

That has massive implications not only for the future health of those 15 million or so kids who are at appropriate weights for their ages, but for future prospects for the nation to better deal with its runaway health care costs.

Abundant research shows that children who are overweight or obese at ages 3 to 5 are five times as likely as their peers with normal weights to be overweight or obese as adults. Given the vast roster of disease associated with obesity, the trend to healthier kids eventually will translate into billions of dollars saved through better health.

A combination of factors appears to be behind the startling improvement.

Researchers said children now consume far fewer calories from sugar-laden beverages than they did in 1999, and that a higher percentage of babies are breast-feeding, contributing to a healthier range of weight gain when they are very young.

Another possible factor is that 10,000 day-care centers nationwide have signed on to a federal initiative to promote healthy eating, ensuring that whatever nutritional gains the kids make at home aren't lost to convenience during the day.

The news is highly encouraging but preliminary. It's crucial to maintain the momentum through insistence on good nutrition in publicly funded food programs and, especially, in school lunch and breakfast programs - along with the elimination of high-sugar drinks from public school campuses.