Objective: To determine whether children's food consumption is increased by the size of the group of children in which they are eating.
Design: Crossover study.
Setting: University based preschool.
Participants: 54 children, aged 2.5-6.5 years.
Interventions: Each child ate a standardised snack in a group of three children, and in a group of nine children.
Main outcome measures: Amount each individual child consumed, in grams.
Results: Amount eaten and snack duration were correlated (r = 0.71). The association between group size and amount eaten differed in the short (<11.4 min) versus the long (> or =11.4 min) snacks (p = 0.02 for the interaction between group size and snack duration). During short snacks, there was no effect of group size on amount eaten (16.7 (SD 11) g eaten in small groups vs 15.1 (6.6) g eaten in large groups, p = 0.42). During long snacks, large group size increased the amount eaten (34.5 (16) vs 26.5 (13.8), p = 0.02). The group size effect was partially explained by a shorter latency to begin eating, a faster eating rate and reduced social interaction in larger groups.
Conclusions: Children consumed 30% more food when eating in a group of nine children than when eating in a group of three children during longer snacks. Social facilitation of food consumption operates in preschool-aged children. The group size effect merits consideration in creating eating behaviour interventions.