Children and young teens who are not overweight but in the higher range of normal weight are much more likely than lean kids to become obese adults, U.S. researchers reported on Thursday.

The study of mostly white children from the Boston area suggests that “normal” weights may in fact be tilting a youngster toward obesity, the researchers reported in the journal Obesity Research.

“We have known that kids who are overweight or obese have a higher risk for being overweight or obese as adults,” said study leader Alison Field, an assistant professor of pediatrics at Harvard Medical School and Children’s Hospital Boston.

“But in this paper, we show that even children in the high normal weight range have an elevated risk of becoming overweight or obese as adults.”

Field’s team looked at 314 children from East Boston who were 8 to 15 years old when their weight, height, and blood pressure were first recorded. They were examined again 8-12 years later.

More than 48 percent of the boys and 23 percent of the girls became overweight or obese between their first childhood visit and the young adult follow-up.

The Centers for Disease Control and Prevention uses body mass index - a measure of height versus weight - to determine normal weight. It classifies children with a BMI between the national 85th and 95th percentiles for age and gender as at-risk for being overweight, and those with a BMI greater than the 95th percentile are classified as overweight.

Children between the 50th and 74th percentile for weight were five times more likely to become overweight, the researchers found.

Girls with a BMI between the 75th and 84th percentile were up to 20 times more likely to become overweight young adults.

Boys between the 75th and 85th percentile of BMI as children were four times more likely to have high blood pressure as young adults.

“These findings underscore that even children who are in the high normal weight range may have adverse outcomes later in life, and our challenge may be even greater than we thought,” said Matthew Gillman, who also worked on the study.

An estimated 15 percent of U.S. children and 65 percent of adults are overweight or obese.