Expectation shapes hunger and craving: placebo effects of verbal suggestion on food-related experiences

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Abstract Background Placebo effects—beneficial outcomes driven by expectations rather than active treatment—are well documented in domains such as pain, mental health, and fatigue. However, their impact on food metabolism and food-related behaviors remains underexplored. Purpose This study investigated whether verbal suggestions about a sham vagus nerve stimulation could alter hunger, food craving, food desirability, and food choice in healthy volunteers. Methods In a randomized, single-blind, between-subjects design (preregistered on Open Science Framework), 126 participants (101 women) were assigned to 1 of 3 groups: a hunger-increasing placebo group, a hunger-decreasing placebo group, or a control group. The hunger-decreasing group was told the stimulation would reduce hunger; the hunger-increasing group was told it would increase hunger; the control group received neutral information. Self-reported hunger and craving were assessed at 4 time points, alongside food desirability ratings and choices between natural and ultra-processed food options. Results The hunger-decreasing group reported reduced overall craving compared to the control group and less hunger compared to the hunger-increasing group after food-related tasks. The hunger-increasing group showed increased hunger but no increase in overall craving. No effects were observed on food desirability or choice. The effect of the suggestions on hunger and craving was not mediated by expectations. Conclusions These findings provide novel evidence that expectations shaped by verbal suggestion can influence food-related experiences, with potential implications for interventions targeting eating habits, eating disorders, and obesity prevention.

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