Maximizing the prophylactic impact of a salubrious diet: A higher-order habit intervention: In P. Lally (Chair), What makes an effective habit-based intervention? [Symposium].

Background: Healthy eating helps prevent chronic illness, yet only 28% of adults eat the recommended amount vegetables. This project aimed to advance the science of maintenance of dietary behaviours by evaluating whether a higher-order habit-intervention for purchasing vegetables increases access within the home-environment. Methods: Participants were 204 adults who ate fewer than three servings of vegetables per day and reported being responsible for most of their own grocery shopping. Participants were randomized into a control or intervention group and received a goal-setting intervention to purchase a variety of vegetables to consume with dinner and an educational video on how to prepare vegetables alongside recipe recommendations. The intervention group also received action- and coping-planning and mental imagery interventions. Participants reported on their vegetable-buying habit, self-efficacy, and purchases immediately post-intervention, weekly over four weeks, and at a three-month follow-up. It was hypothesized that the intervention group would increase more strongly over time on these constructs in comparison with control. Findings: Using repeated-measures ANOVAs, it was found that both groups increased on habit (F = 18.71; p < .001), self-efficacy (F = 4.82; p = .001) and decreased on vegetable purchases (F = 6.81; p < .001) over the course of the study. These changes did not differ between groups (ps > .05). Discussion: A one-off habit intervention did not improve vegetable-buying habits or behaviour more than an education and goal-setting intervention. Thus, when given adequate resources, individuals may be motivated to perform a behaviour and more easily form habits on their own.