The association of impulsivity with effects of the ChooseWell 365 workplace nudge intervention on diet and weight.

Impulsivity is associated with unhealthy food choices. Nudge interventions in the food environment may be particularly helpful for individuals with high impulsivity. To examine if trait, choice, and action impulsivity were associated with the effectiveness of a workplace-based nudge intervention to improve diet and weight. This was a planned secondary analysis of 487 participants of ChooseWell 365, a randomized controlled trial that tested a 12-month nudge intervention to improve cafeteria purchases among hospital employees. Trait impulsivity was measured with the Barratt Impulsiveness Scale. Choice and action impulsivity were assessed with delay discounting and response inhibition tasks, respectively. Tertiles were generated for each measure. Multivariable regression models examined the association of impulsivity with cafeteria purchases [Healthy Purchasing Score (HPS)] over 12 months, dietary intake [Healthy Eating Index-2015 (HEI) score], and body mass index (BMI) measured at 12 months. Interaction terms tested differences in intervention effect by level of impulsivity. Participants with higher trait (p = .02) and choice (p < .001) impulsivity had lower baseline HPS than those with lower impulsivity. Employees of all impulsivity levels increased healthy eating, but higher trait impulsivity was associated with smaller increase in HPS over 12 months (p = .03). In the highest action impulsivity tertile, 12-month BMI increased less for intervention vs. control participants (0.3 vs. 0.5 kg/m2; p-interaction = .04). There were no interaction effects for trait or choice impulsivity. A workplace nudge intervention improved food choices among employees of all impulsivity levels and attenuated weight gain in those with higher action impulsivity.