A new study by University of North Carolina School of Medicine pediatrics researchers finds a surprising difference in the eating habits of overweight children between ages 9 and 17 years compared to those younger than 9.

Younger children who are overweight or obese consume more calories per day than their healthy weight peers. But among older overweight children the pattern is reversed: They actually consume fewer calories per day than their healthy weight peers.

How to explain such a seemingly counterintuitive finding?

“Children who are overweight tend to remain overweight,” said Asheley Cockrell Skinner, PhD, assistant professor of pediatrics at UNC and lead author of the study published online Sept. 10, 2012 by the journal Pediatrics.

“So, for many children, obesity may begin by eating more in early childhood. Then as they get older, they continue to be obese without eating any more than their healthy weight peers,” Skinner said. “One reason this makes sense is because we know overweight children are less active than healthy weight kids. Additionally, this is in line with other research that obesity is not a simple matter of overweight people eating more — the body is complex in how it reacts to amount of food eaten and amount of activity.”