Overnight fasting affects avoidance learning and relief

ABSTRACT

Objectives: prolonged fasting influences threat and reward processing, two fundamental systems underpinning adaptive behaviors. In animals, overnight fasting sensitizes the mesolimbic-dopaminergic activity governing avoidance, reward, and fearextinction learning. Despite evidence that overnight fasting may also affect reward and fear learning in humans, effects on human avoidance learning have not been studied yet. Here, we examined the effects of 16 h-overnight fasting on instrumental avoidance and relief from threat omission.

Methods: to this end, 50 healthy women were randomly assigned to a Fasting (N = 25) or a Re-feeding group (N = 25) and performed an Avoidance-Relief Task.

Results: we found that fasting decreases unnecessary avoidance during signaled safety; this effect was mediated via a reduction in relief pleasantness during signaled absence of threat. A fasting-induced reduction in relief was also found during fear extinction learning.

Discussion: we conclude that fasting optimizes avoidance and safety learning. Future studies should test whether these effects also hold for anxious individuals.

KEYWORDS:

• Fasting
• avoidance
• extinction
• reward
• relief
• anxiety

Acknowledgments

BV, LVO and SP developed the concepts of the study and study design; SP and LN performed the collection of the data; SP performed the data analysis and interpretation under the supervision of BV and LVO; SP drafted the manuscript under the supervision of BV, TB, and LVO. All the authors provided revisions, conceptual and statistical feedback, and approved the final version of the manuscript for submission.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Original data are stored and secured within the KU Leuven facilities given ethical reasons. Processed anonymous data are available on the Open Science Framework (OSF), https://osf.io/b3rgd.

Additional information

Funding

This work was supported by a KU Leuven [grant number STG-18-00299], KU Leuven Internal Funds (Special Research Fund, BOF), Consolidator Grant 648176 of the European Research Council, ERC, Horizon 2020.

Notes on contributors

Silvia Papalini

Silvia Papalini is a PostDoc researcher. She investigates the interaction between the hunger, reward, and fear brain system, in healthy as well as in the clinical population.

Laura Neefs

Laura Neefs is a master student in clinical psychology who participated to the conduction of the present study. She successfully completed her thesis on fasting.

Tom Beckers

Tom Beckers is a professor in psychology. His research concerns fundamental processes of learning and memory in children and adults and in rodents, using behavioural, neurobiological, and computational techniques.

Lukas Van Oudenhove

Lukas Van Oudenhove is an associated professor and psychiatrist. He studies the interactions between the gastrointestinal tract, including the microbiota, and the brain in humans using functional brain imaging techniques.

Bram Vervliet

Bram Vervliet is a professor in psychology. His research aims to connect associative learning theory, clinical psychology and translational neuroscience for the advancement of psychotherapies.