Unhealthy, but not healthy, positional nudge during Ramadan affects the caloric content of meal choice among Indonesians with high BMI

We tested for an asymmetric effect of food positional nudge biased towards the unhealthy for individuals with different BMI and fasted states. Data from 141 Indonesian participants were analysed. Participants completed the single-person Fake Food buffet twice, which offered healthy (e.g., roasted chicken) and unhealthy (e.g., fried chicken) options. Ramadan fasting was incorporated as a natural experimental condition by having participants complete the buffet during non-Ramadan and Ramadan periods. In addition, participants were randomly assigned to one of three positional nudge experimental conditions: control, healthy, and unhealthy. Control positional nudge had a balanced 2-to-2 healthy-unhealthy food placement in the buffet. In contrast, the healthy positional nudge had a starting 3-to-1 ratio, biased towards healthier food options, placed at the start of the buffet. The unhealthy positional nudge had a 3-to-1 starting ratio, biased towards more unhealthy options. The main results revealed an asymmetric effect that is biased towards an unhealthy positional nudge for fasted participants with high BMI. This bias was not reversed with a healthy positional nudge. The present findings raise questions about whether healthy positional nudges alone are sufficient in contexts involving high hunger and individuals with higher BMI, although further research with larger samples and more precise designs is needed before drawing policy conclusions.