Neural activity in self-related brain regions in response to tailored nutritional messages predicts dietary change

Overweight and obesity have become international public health problems, so there is an urgent need to implement effective interventions that prevent these concerning health issues. Designing personalized (tailored) dietary communications has become one of the most effective tools in reducing unhealthy eating behavior, when compared with one-size-fits-all messages (untailored). However, more research is required to gain a complete understanding of the underlying mechanisms by which tailored nutritional messages elicit reductions in unhealthy dietary behavior. To the best of our knowledge, our study may be the first to use neuroimaging, namely functional magnetic resonance imaging (fMRI), aiming to evaluate the neural basis of tailored and untailored nutritional messages and assess how these neural responses predict unhealthy food intake reduction after a month receiving tailored nutritional messages. To that goal, 30 participants were scanned while reading tailored and untailored nutritional messages. Subsequently, for a month, they received tailored interventions encouraging healthy food intake. The neural findings reveal that when compared to untailored communications, tailored messages elicit brain networks associated with self-relevance, such as the precuneus, the middle temporal gyrus, the hippocampus, the inferior orbitofrontal cortex (OBC), the dorsomedial prefrontal cortex (dMPFC), and the angular gyrus. Interestingly, among these self-related brain areas, the dMPFC, OFC, angular gyrus, and hippocampus forecast reductions in unhealthy food intake after a one-month tailored intervention for the cessation of unhealthy eating. These results may offer implications for clinicians, practitioners, and/or policymakers who should implement substantial efforts in creating individualized campaigns focused on their target's perceived needs, goals, and drivers in relation to eating healthy to reduce overweight issues. This research therefore constitutes a step forward in showing a direct association between the neural responses to tailored nutritional messages and changes in real-life healthy eating behavior.

Under pressure: Nudging increases healthy food choice in a virtual reality supermarket, irrespective of system 1 reasoning

Previous research has shown that nudging can effectively support people's healthy food choices. Yet, to date knowledge about the psychological premises of nudging is limited, highlighting the need for closer scrutiny to determine how and when nudging is most effective. In the current study, we assessed whether the presumed effect of nudging on healthy food choice is enhanced under time pressure, a condition probing alleged system 1 reasoning. Food choice was studied in a realistic virtual reality supermarket where healthier alternatives were nudged by making them more salient. We additionally explored possible differences in decision-making experiences related to nudging or time pressure. The study took place at a science festival where visitors could decide to participate in a study. Participants (n = 99) had to purchase four products, each from a different product category that was provided on a shopping list. In the nudging condition, one healthier option within each product category was nudged by making it more salient. While a main effect of nudging was found, showing in increased healthy food choices, this effect was not further qualified by time pressure, suggesting that the effectiveness of nudging is not enhanced under system 1 conditions. Relatedly, people who were and who were not aware of the nudges showed similar effects of nudging on healthy food choice. Furthermore, no differences in decision-making experiences showed, suggesting that people have similar experiences regarding impulsive and reflective decision-making irrespective of whether they are being nudged or put under time pressure. All in all, our findings are in line with recent viewpoints on the premises of nudges, suggesting that alleged system 1 conditions are not a prerequisite for nudging to be effective.

The effects of nudging and pricing on healthy food purchasing behavior in a virtual supermarket setting: a randomized experiment

BACKGROUND

Evidence on what strategies - or combination of strategies - are most effective and equitable in promoting healthier diets is needed. This study examined the efficacy of nudging and pricing strategies on increasing healthy food purchases and the potential differential effect by socio-economic position (SEP) among Dutch adults in a virtual supermarket.

METHODS

A randomized study design was conducted within a virtual supermarket (SN VirtuMart). Participants were exposed to five within-subject study conditions (control, nudging, pricing, price salience and price salience with nudging) and randomized to one of three between-subject study arms (a 25% price increase on unhealthy products, a 25% discount on healthy products, or a 25% price increase and discount). In total, 455 participants of low and high SEP (using either education or income as proxy) were randomized to conduct their weekly shopping in a virtual supermarket for five consecutive weeks. The primary outcome included the percentage of healthy purchases. Data were analyzed using linear mixed models.

RESULTS

In total, 346 (76%) adults completed all five shops within the SN VirtuMart. Median age was 32.5, 49.2% had high education and 32.8% had high income. Out of the 12 conditions, four conditions were statistically significantly different from the control condition. Nudging and non-salient pricing strategies alone did not statistically significantly increase healthy food purchases, whereas a combination of salient price increases and discounts led to an increase in the percentage of healthy food purchases (B 4.5, 95%CI 2.6; 6.4). Combining salient pricing and nudging strategies led to increases in the percentage of healthy products in all three pricing arms, with largest effects found in the combined price increase and discount arm (B = 4.0, 95%CI = 2.0; 6.0). Effects were not modified by SEP.

CONCLUSIONS

Combining health-related price increases and discounts and combining these salient pricing strategies with nudges in a supermarket setting seems to stimulate healthy food purchases for both low and high SEP populations. However, further research in real-world settings is needed.

TRIAL REGISTRATION

This randomized trial ( NTR7293 ) was registered in the Dutch trial registry ( www.trialregister.nl ).