Researchers found that super-sizing preschoolers' entrees generally led the children to take bigger bites and consume more calories. But when kids were allowed to serve themselves, they naturally selected more age-appropriate portions.

"Given the alarming and growing problem of child obesity, the capacity of large portions to encourage overeating among young children is concerning," study author Dr. Jennifer Orlet Fisher told Reuters Health.

"The results of the study imply that minimizing children's exposure to excessive portions may prevent overeating," said Fisher, of the U.S. Department of Agriculture (news - web sites)'s Children's Nutrition Research Center at Baylor College of Medicine in Houston.

One recent study found that meal portion sizes in the home and restaurants have jumped since the late 1970s in the U.S.

In the current study, Fisher and her team studied 30 preschool-aged children.

During two series of lunches the children were served either an age-appropriate portion of a macaroni-and-cheese entrée or a portion twice as large.

The researchers found that, overall, the children ate about 25 percent more of the entrée when they were served a larger portion than when they were served an age-appropriate amount.

Children took bigger bites when presented with the bigger entrée and did not compensate by eating significantly less of the other foods served with it, Fisher and her colleagues report. The children's overall calorie intake at lunch was 15 percent higher when served the large entrée.

In addition, the children's bite size increased along with increasing body mass index, a measure of a person's weight in relation to their height.

In another part of the study the children were allowed to serve themselves from bowls containing individual servings of the larger portion sizes. They were told to eat as little or as much as they wanted.

This time, the children did not overeat, the researchers found. They instead chose smaller portions and ate less than when they were served the larger portion size.

In light of the findings, Fisher suggested that children be served or encouraged to select "small 'first portions' with additional helpings if (they) are still hungry."

"Also avoid the temptation of 'super-sizing"' when eating out, she added. "Such deals appear not to represent a good value for health."

SOURCE: American Journal of Clinical Nutrition (news - web sites) 2003;77:1164-1170.