Why do some kids stop eating when they’re full while others keep going? New research from Penn State suggests the answer may differ between boys and girls.
In a study of 64 children ages 4 to 6, boys ate less at a meal if they had already had a snack of fruit beforehand. Girls, however, ate the same amount of food whether or not they had eaten fruit.
“Boys in this study adjusted the total number of calories they consumed during the meal to accommodate their snack intake,” said Kathleen Keller, professor of nutritional sciences at Penn State and senior author. “That boys adjusted for their snack is a good thing — it suggests that they are able to listen to their bodies. Girls, on the other hand, may have been eating based on other social or environmental cues around them, regardless of their hunger.”
The researchers tested different forms of fruit, apple slices, applesauce or juice, but found the form didn’t change results. Both boys and girls consumed roughly the same amount of the pre-meal snack, but only boys cut back later during the meal.
The reasons for the difference weren’t measured directly, but Keller said cultural and developmental factors likely play a role. She noted that girls are often socialized earlier to pay attention to external messages about food, while boys may continue relying on internal hunger signals for longer.
“There is evidence showing that all babies — boys and girls — are able to regulate how much they eat,” Keller said. “They eat when they are hungry and stop when they are full. But as they age, humans lose this natural ability as they learn to read social cues for how much they should eat.”
The findings matter for parents, Keller added. Encouraging kids to focus on their own hunger and fullness, rather than always eating on schedule or in response to portion size and packaging, may help preserve those natural cues.
“For as long as possible, parents should encourage children to focus on how they feel internally,” Keller said. “It is important for kids to understand when they are eating for hunger and when they aren’t. All of us snack occasionally when we aren’t hungry, but when we do this repeatedly without checking in with our bodies, it can become problematic.”
This study, which was published in Appetite, was funded by the Social Science Research Institute at Penn State, with additional support from the National Center for Advancing Translational Sciences. Salary support for Dr. Kathleen Keller came from a USDA Hatch Grant.