Placebo Effects on Hunger and Food Craving: The Role of Body Image and Gender

Eating beyond the required calorie intake is a characteristic in various health complications, such as obesity or binge eating disorder. This is often ascribed to our hedonic brain system, which causes us to eat for pleasure rather than hunger. The placebo effect is defined by symptom improvement in response to an inactive treatment due to expectations on its effectiveness, and has been shown to successfully alter the physiology and psychology of humans. The current project aims to investigate whether a sham vagus nerve stimulation, accompanied with placebo suggestions, can reduce hunger and food craving in normal-weight participants. Additionally, the potentially moderating effects of body image and gender are explored. In total, 66 volunteers (M = 21.3 years old, 74% female) were invited to the laboratory and allocated to either placebo or control group. All participants received a 2-minute sham stimulation, however, only the placebo group were told the intervention is expected to...Show moreEating beyond the required calorie intake is a characteristic in various health complications, such as obesity or binge eating disorder. This is often ascribed to our hedonic brain system, which causes us to eat for pleasure rather than hunger. The placebo effect is defined by symptom improvement in response to an inactive treatment due to expectations on its effectiveness, and has been shown to successfully alter the physiology and psychology of humans. The current project aims to investigate whether a sham vagus nerve stimulation, accompanied with placebo suggestions, can reduce hunger and food craving in normal-weight participants. Additionally, the potentially moderating effects of body image and gender are explored. In total, 66 volunteers (M = 21.3 years old, 74% female) were invited to the laboratory and allocated to either placebo or control group. All participants received a 2-minute sham stimulation, however, only the placebo group were told the intervention is expected to have hunger-reducing effects. A placebo score for hunger and food craving was calculated based on the difference between pre- and post-stimulation ratings. The t-test revealed that the placebo suggestions significantly decreased food craving (d = 0.69, p = .008), but not hunger (d = 0.40, p = .111). The moderation analysis showed a significant interaction effect between body image and group allocation on food craving; a more negative body image resulted in a smaller decrease in food craving for the placebo group (f2 = 0.25, 95% CI [0.24, 2.35], p = .017). The placebo effect on hunger was not shown to be moderated by body image (p = .370). Gender had no moderating effect on either relationship (p = .534; p = .726). The study reveals that food craving can be more affected by the placebo induction than hunger. Body dissatisfaction seems to alter the individual’s perception of food craving and moderates the relationship between the placebo effect and food craving. In conclusion, food craving needs to be prioritized in future interventions for health adversities related to overeating. The buffering effects of body image need to be considered as a potential risk factor in early developing stages of eating pathology.Show less

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Placebo Effects on Hunger and Food Craving: The Role of Body Image and Gender