Children’s portion-size effect for sugar-sweetened beverages and water in two field experiments: Moderating effects of liking and family socioeconomic status

Abstract

This is a pre-print of a paper that is currently under review. Background: Childhood overweight and obesity are urgent health problems, especially among children from families with lower socioeconomic status. In the present study, we examined the contribution of large portions of sugar-sweetened beverages (SSBs) to excess calorie intake among children. While children have been shown to consume more food from large compared to small portions, this so-called ‘portion-size effect’ has not been systematically examined for beverages. Here, it was tested whether children consume more from larger compared to smaller portions of SSBs and water, and whether this portion-size effect is moderated by liking of the drink and family socioeconomic status. Methods: Two large-scale field experiments were conducted in which children (N = 364; 6-17 years) were offered a small (170 ml) or a large (275 ml) portion of a SSB or water to consume while they were completing a questionnaire. Liking of the drink and family socioeconomic status were also assessed. Results: Children showed a strong portion-size effect, consuming 55-56 ml more SSB and 37 ml more water from the larger portion. The portion-size effect was larger among children who liked the SSB or water. While the portion-size effect for the SSB was not moderated by family socioeconomic status, the “healthy” portion-size effect for water was stronger among children from families with higher socioeconomic status. Conclusions: Reducing the portion size of SSBs available to children could play a key role in curbing excess calorie intake. In the absence of other interventions, however, simply providing large portions of water may benefit especially the intake of children from more privileged backgrounds.