Encouraging vegetable intake as a snack among children: the influence of portion and unit size

OBJECTIVE: People eat more unhealthy foods when served more (portion size effect) and when the food is served in larger units (unit size effect). The present study aimed to examine whether these effects can be used for the good: to increase vegetable consumption among children. DESIGN: A 2×2 between-subjects experiment was conducted at two schools. Pupils were presented in class with cucumber that varied both in unit size (one piece v. pre-sliced) and portion size (one-third v. two-thirds of a cucumber). Children ate ad libitum during the morning break and filled in a survey. SETTING: Primary schools in the centre of the Netherlands. SUBJECTS: Primary-school pupils (n 255) aged 8-13 years. RESULTS: Children ate 54 % more cucumber when served a large compared with a smaller portion (difference of 49 g; P