Rooted in routine: Fostering higher order vegetable-shopping habits using a randomised simple planning intervention.

A healthy diet is a protective factor against a host of negative health outcomes. To maintain such a diet necessitates the consumption of at least 240 g of vegetables per day. However, most of the population fails to meet this threshold. Utilising a randomised controlled trial, the present study tested the effectiveness of a one-off higher order habit intervention aimed at shopping for a variety of vegetables and the mechanisms that may support such habit development. Specifically, participants (N = 198; 54.5% female; 20 to 74 years of age) were allocated to the intervention or control group to explore (1) how effective an action- and coping-planning intervention is at targeting the formation of vegetable-shopping higher order habits and (2) whether healthy-eater identity, intrinsic motivation and self-efficacy were mechanisms of action. Follow-up measures of habit, the mechanisms of action and behaviour were taken post-intervention, weekly for 4 weeks and at 3- and 6-month follow-ups. The intervention led to stronger higher order habit formation after 6 months and that it was particularly effective for those with low baseline higher order habits for vegetable shopping. These findings demonstrate that a simple, one-off, intervention can lead to long-lasting change in higher order habits within the nutrition domain.