Pudgy toddlers face a good chance of becoming overweight 12-year-olds, according to government research that shoots down the notion that kids just naturally outgrow early chubbiness.

Children who were overweight at age 2 or later during their preschool years faced a five times higher risk of being overweight at age 12 than youngsters who were not overweight early on, the study found. Sixty percent of the children who were overweight at any time during the preschool period were overweight at age 12.

Children were considered overweight if their body-mass index was in the 85th percentile or higher for their gender and age. That means they were heavier than at least 85 percent of children their same age and sex.

“These results suggest that any time a child reaches the 85th percentile for BMI may be an appropriate time for intervention,” the researchers wrote.

“These findings underscore the need to maintain a healthy weight beginning in early childhood. Contrary to popular belief, young children who are overweight or obese typically won’t lose the extra weight simply as a result of getting older,” said Dr. Duane Alexander, director of the National Institute of Child Health and Human Development, which funded the study.

The researchers also found that 40 percent of children whose BMIs were between the 50th and 84th percentiles by age 3 – or in the normal to high-normal range – were overweight at age 12. By contrast, no children with a body-mass index below the 50th percentile throughout elementary school had become overweight by age 12.

“It is clear that the longer a child remained in the lower range of normal BMI, the less likelihood there was that the child would become overweight by early adolescence,” the researchers said.

The study was prepared for release Tuesday in September’s issue of Pediatrics.

It involved 1,042 U.S. children born in 1991, “basically right during the time when the obesity epidemic was hitting” the nation, said lead author Dr. Philip Nader, a pediatrician and professor emeritus at the University of California at San Diego.

Participants’ height and weight were measured seven times from ages 2 to 12. Previous studies have shown that a child’s weight during adolescence is a good predictor of weight in adulthood, Nader said.

Similar to recent national estimates, by the study’s end about one-third of the children were overweight, about three times higher than the percentage a generation earlier, Nader said.

Critics say body-mass index, a height-to-weight ratio, isn’t always an accurate gauge of excess fat, particularly in growing children. But Nader said high BMIs are a “generally accepted surrogate measure for being overweight.” And in young children, a high BMI is more likely to reflect excess fat than excess muscle, he said.

While the study shows that chubby toddlers risk becoming chubby adolescents, “it’s not hopeless news,” Nader said. Instead, the results should prompt “a call to action” for parents, schools and community planners to provide young children with healthy food and safe places to walk and play, he said.

Dr. Matt Longjohn, executive director of the Consortium to Lower Obesity in Chicago Children, said the study “tells us that early prevention is best.”

His group promotes anti-obesity efforts with schools but also helps develop programs for younger children through churches, parks and other community organizations.

“The teachable moments for kids and parents are very often in these younger years,” Longjohn said.