A mixed methods exploration of the psychological effects of short term fasting in healthy individuals

Aim: The current study aims to expand on the existing fasting literature in relation to anorexia nervosa. It provides an in-depth account of the psychological experience of fasting in healthy individuals as a way to disentangle the effects of starvation from the overall phenomenology of anorexia nervosa. Method: The study was mixed method in approach, employing a Small-N multiple single case design, alongside qualitative interviews. 14 healthy females fasted for 20 hours. During the fast EMA measures were completed at two hourly time points and participants answered semi-structured interviews about their experiences following completion of the fast. Results: Results showed each individual’s experience of fasting to be unique, however a number of common factors were identified. Several participants described a positive emotional experience and an increase in negative emotion on recommencement of eating, suggesting the reinforcing value of emotion. In addition, the role of intrusive thoughts, and subsequent behavioural and cognitive strategies employed to manage these, were described by many participants. Conclusions: Findings suggest that a number of psychological mechanisms are employed by healthy individuals in order to cope with the experience of fasting which impact on cognitive flexibility. This indicates that some of the cognitive inflexibility and emotional experience of individuals with anorexia nervosa is related to starvation. In addition, once these strategies have been developed it might be harder for some individuals to recommence eating for reasons including increased weak central coherence, being ‘stuck in set’ and the reinforcing value of positive emotions. This has considerable implications in terms of unintentional food restriction and for the treatment of anorexia nervosa