PurposeSelf-efficacy has often been found to play a significant role in healthy dietary behaviours. However, self-efficacy interventions most often consist of intensive interventions. The authors aim to provide more insight into the effect of brief self-efficacy interventions on healthy dietary behaviours.Design/methodology/approachIn the present article, two randomized controlled trials are described. In study 1, a brief self-efficacy intervention with multiple self-efficacy techniques integrated on a flyer is tested, and in study 2, an online brief self-efficacy intervention with a single self-efficacy technique is tested.FindingsThe results show that a brief self-efficacy intervention can directly increase vegetable intake and indirectly improve compliance to a diet plan to eat healthier.Originality/valueThese findings suggest that self-efficacy interventions do not always have to be intensive to change dietary behaviours and that brief self-efficacy interventions can also lead to more healthy dietary behaviours.