Negative emotions hijack food choices in bulimia
People with bulimia nervosa respond differently to negative feelings than people without an eating disorder. That difference shows up in how quickly and strongly taste drives food selection. A new study maps the decision-making process at the moment it breaks down.
Bulimia nervosa is an eating disorder characterised by cycles of binge eating alternating with restriction. What exactly triggers the shift from control to loss of control was unclear. The researchers had 25 women with bulimia and 21 healthy women complete two sessions: one with a neutral mood and one following a negative mood induction. Participants then chose between food options while a computational model tracked their decision-making process.
The model, a time-varying diffusion decision model, measured how quickly and how strongly taste was weighted relative to healthiness in each choice. In a negative mood, both groups weighted taste sooner, but the effect was stronger in women with bulimia. Moreover, a stronger bias in the lab was associated with more frequent subjective binge episodes three months later. The study, published in eLife, is based on a small sample and laboratory observations; the findings are preliminary.
Ageing and eating behaviour: an indirect link
Bulimia connects to ageing indirectly. Chronic binge eating is associated with metabolic dysregulation, inflammation and elevated oxidative stress. These processes accelerate biological ageing. From a longevity perspective, understanding why emotions so strongly influence eating behaviour matters: those who understand this mechanism can develop more targeted interventions.
The mechanism behind loss of control
The study provides the first quantitative picture of the decision-making process itself. It is not only about what someone chooses, but about when and how strongly taste information enters the choice process. In women with bulimia, taste did so earlier and more compellingly under negative mood. In a neutral mood, they actually applied a more restrictive pattern. That explains the fluctuations in eating behaviour that define the disorder.
Whether similar mechanisms contribute to unhealthy eating in people without an eating disorder over the longer term is a question this research opens but does not yet answer.
Search terms to explore further: diffusion decision model food choice | affect-induced eating behaviour bulimia | emotion regulation binge eating