One of the study’s authors, Dr Charlotte Hardman, from the Nutrition and Behaviour Unit in the University's School of Experimental Psychology, told FoodNavigator.com: "Children who are familiar with a particular snack food expect it to be more filling than one they are unfamiliar with. Similarly, they tend to select a bigger portion size of a snack food with which they are unfamiliar.
“So, 'fullness expectations' are important determinants of meal-size selection. Foods that are believed to be more filling are selected in smaller portions."
The research revealed that children who were infrequent consumers relied on food’s physical appearance, such as volume, in forming their judgments about fullness. That strategy that lead them to select larger portion sizes of foods with which they were unfamiliar.
The finding suggests that familiarity with snack foods helps children to learn about fullness.
"Presenting children with a wide variety of different snack food products may make it difficult to predict their fullness,” said Hardman. “Our study suggests that if parents choose to give snack foods to their children, they may wish to stick to the same products.
“Giving children a wide range of different snack foods means that they never have sufficient opportunity to become familiar with them. So, they can’t learn how full they expect to feel after eating them and that can encourage the selection of larger portion sizes.”
Also, higher consumption of snacks which included large amounts of calories, exacerbated the negative health impact of over eating.
The research confirms previous research with adults, which showed that beliefs and expectations about how filling foods will be influence the selection of portion sizes.
The study focused on 70 children between the ages of 11 to 12. A computer exercise was used to measure the fullness that they expected after eating different snack foods. The children also recorded how often they ate the snack foods.
Further research should focus on how to use this information to make interventions designed to encourage healthy eating patterns. “It would be interesting to define products that are perceived as being more filling,” said Hardman.
“Also, there’s some evidence that labelling can influence people’s perception of the level of fullness associated with food products. Understanding more about this could lead to helpful interventions.”
Meanwhile, obesity-related illness is estimated to cost the UK National Health Service alone £9bn a year.
Source: American Journal of Clinical Nutrition, published online ahead of print.
Title: Children’s familiarity with snack foods changes expectations about fullness.
Authors: C Hardman, K McCrickerd and J Brunstrom