Acute fasting modulates autonomic nervous system function and ambulatory cardiac interoception.

Area of Science:

• Psychophysiology
• Autonomic Nervous System Research
• Nutritional Neuroscience

Background:

• Intermittent fasting (IF) is linked to various health benefits.
• Fasting may alter psychophysiological functioning, potentially improving interoception.
• Interoception is the perception of internal bodily signals.

Purpose of the Study:

• To investigate if IF alters autonomic nervous system (ANS) activity.
• To determine if IF enhances interoceptive accuracy and sensibility in daily life.
• To explore the relationship between ANS changes and interoceptive improvements during IF.

Main Methods:

• Two within-subjects studies were conducted.
• Study 1: Assessed ANS changes (heart rate variability, RMSSD) after a 16-hour fast.
• Study 2: Used ecological momentary assessment to measure interoceptive accuracy and sensibility during IF and normal eating periods.

Main Results:

• A 16-hour fast increased heart rate variability (RMSSD), indicating a shift towards vascular over myocardial response.
• A tendency towards higher interoceptive accuracy and sensibility was observed during intermittent fasting.
• This effect was more pronounced in individuals with lower RMSSD.

Conclusions:

• Short-term intermittent fasting appears to improve attention to internal bodily cues.
• Alterations in autonomic nervous system function during fasting may underlie enhanced interoception.
• Findings suggest IF could be a tool for improving interoceptive awareness.