Two pilot interventions were conducted which examined the influence of peer-led nudging on social media as a way of influencing self-reported ideal portions of high energy-dense snacks and sugar-sweetened beverages. In both interventions the peers posted images of 'their' snacks and beverages, which constituted the recommended portion, onto an Instagram account. The peers also posted images relating to portion sizes, calories and other information related to health but not specifically portion size. It was hypothesised that viewing images of peers' snacks would influence the participants to reduce their own snack and beverage ideal portion sizes.~Intervention 1 lasted for 2 weeks and recruited young adults and used a within-subjects design. Intervention 2 lasted for 4 weeks and recruited adolescents and used a between-subjects design. In intervention 2, participants were randomly assigned to either the intervention or the control condition. This protocol focusses on intervention 2.~In both interventions, participants in the intervention condition were added to an Instagram account and were required to visit Instagram daily and to like all posts. All participants (intervention and control) completed a survey at baseline and at the end of the intervention, and completed quizzes at the end of each week.
The 2 interventions aimed to examine whether peer-led nudging on social media may be a way of influencing young adults and adolescents to reduce their self-reported ideal portion sizes of high energy-dense snacks and sugar-sweetened beverages.