When does a fasting-associated clock shift become durable?
For longitudinal epigenetic responses to long-term fasting, the key comparison is not only baseline versus the end of fasting, but also repeated sampling after refeeding and metabolic stabilization. Does any apparent age shift persist beyond acute changes in cell composition, hydration, inflammation, and substrate use—and does its magnitude exceed each participant’s pre-intervention variability? The consequential result would be a durable within-person change that predicts later function or morbidity, rather than a reversible fasting-state signature.
