Serve your preschoolers supersized food portions and you'll likely wind up with supersized kids.

A new study shows that, unlike some calorie-conscious adults, children don't eat less at dinner if they eat a big lunch and are more likely to eat whatever portion size is put on their plate.

Researchers say those findings suggest that parents and caregivers may bear a greater responsibility for controlling children's weight and preventing childhood obesity that some realize.

"We found that the more food children are served, the more they eat, regardless of what they've eaten previously in the day, including how big their breakfast was," says researcher David Levitsky, professor of nutritional sciences at Cornell University, in a news release. "We also found that the more snacks children are offered, the greater their total daily food and calorie intake."

Read WebMD's "Portion Sizes Eventually Add Up"

Portion Size Matters to Kids' Weight

In the study, which appears in the June issue of Appetite, researchers monitored how much 16 preschool children, aged 4-6, ate for about a week in day care centers and had their parents keep food diaries of what they ate at home in the evenings and on weekends.

The results showed that how much food was served to the children had the biggest impact on how much they ate in a meal or snack, regardless of the calorie or fat content of that meal or other meals eaten within the previous 24 hours.

The study also showed that children who were offered snacks between meals did not eat less at subsequent meals.

Researchers say these findings conflict with earlier studies that suggested that children may be better than adults at regulating their food intake. But they say those studies were done under laboratory conditions and may not represent how children eat under real-life conditions.

"We found that portion size is, by far, the most important factor in predicting how much a child will eat," says Levitsky. "These findings suggest that both the onus of controlling children's weight -- both in causing overweight in children as well as in its prevention -- must rest squarely in the hands of parents and other caregivers."

Read WebMD's "Slimming Foods for Summer"

By Jennifer Warner, Reviewed by Brunilda Nazario, MD

SOURCES: Mrdjenovic, G. Appetite, June 2005; vol 44: pp 273-282. News release, Cornell University.