Acute fasting modulates autonomic nervous system function and ambulatory cardiac interoception.
Level 3 - non-randomized controlled study
Two within-subjects experimental and ecological momentary assessment studies with no explicit randomization described
PubMed 38331345 · doi:10.1016/j.biopsycho.2024.108760
What was done
Two within-subjects studies evaluated the physiological and perceptual effects of acute fasting. Study 1 (N = 36) measured laboratory autonomic nervous system changes after a 16-hour fast. Study 2 (N = 40) utilized an ambulatory ecological momentary assessment design comparing three consecutive days of intermittent fasting (16-hour fast with an 8-hour eating window) against three consecutive days of normal 24-hour eating to measure cardiac interoceptive accuracy and subjective interoceptive sensibility in daily life.
What was found
Study 1 demonstrated an increase in heart rate variability—specifically the root mean square of successive differences (RMSSD)—along with a more vascular than myocardial response following the 16-hour fast. Study 2 showed a tendency toward higher interoceptive accuracy and sensibility during the fasting condition compared to normal eating, which was especially pronounced in participants exhibiting lower RMSSD. The abstract reports no numeric values, effect sizes, or p-values.
Why it matters
This study provides evidence that short-term intermittent fasting may acutely enhance conscious perception of internal cardiovascular signals via changes in autonomic regulation.
Limits
Both study samples were small (N = 36 and N = 40), and the abstract provides no exact quantitative metrics, confidence intervals, or statistical test values. Participant demographics, health status, counterbalancing, and randomization details are not specified, and the main interoceptive findings were characterized only as a tendency.
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