¹University College Cork, APC Microbiome Ireland, Cork, Ireland

Background: Obesity is associated with both anxiety and depression, often leading to maladaptive emotional eating behaviours that cause and maintain obesity, such as stress-eating. While the causes behind problematic eating behaviours are poorly understood, it is vital to target these behaviours in order to help patients develop and maintain healthy eating patterns and to treat obesity sustainably. Interestingly, obesity, stress and mental health share several common features, including metabolism, inflammation and endocrine signalling. Firmly at this intersection sits the gut microbiome, known to greatly influence both metabolic and mental health, including stress. As such, microbiota-target interventions may be a viable treatment option for emotional and stress-induced eating behaviours and, by extension, obesity.

Aims & Objectives: The present study aimed to unravel the role of the microbiome in stress-induced eating behaviour and to validate microbiota-targeted intervention approach to treat stress-eating.

Method: Stress-eating was induced in male mice through social defeat stress twice for two days. This was followed by two sessions of access to high-fat high-sugar (HFHS) diet for two hours over two days to measure binge-like palatable food intake. To investigate the impact of the microbiome, the stress-eating experiment was then repeated in mice with a depleted microbiome through an antibiotic cocktail (ABX) in the drinking water. Lastly, faecal matter from stressed or control mice was transplanted (FMT) to non-stressed mice and HFHS diet intake was measured in the same manner.

Results: Two days of social defeat stress successfully increased HFHS diet intake by 43% compared to control, while no difference was seen in normal food intake. Although ABX-treated mice in general ate more HFHS diet than untreated mice, there was no difference between stressed or control mice. Further, the FMT could effectively replicate the stress-induced eating, where mice transplanted with faecal matter from stressed animals ate 45% more than those that received faecal matter from control mice.

Discussion & Conclusions: In the present study binge-like intake of HFHS food was induced by the means of a short social defeat stress to model stress-eating. Interestingly, ABX-treated mice did not show any effect of stress on food intake and the stress-induced eating could be almost perfectly replicated by FMT alone. Taken together, these results suggest that the gut microbiome is both essential and sufficient to mediate stress-induced eating behaviour.
The knowledge that the gut microbiome is of such importance for stress-eating behaviour identifies microbiota-targeted interventions as a viable target to treat emotional eating behaviours with the potential to help treat obesity in a sustainable manner.