Effects of Day-On-Day-Off Fasting on Telomere Length

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Authors: Ali Clapp
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Abstract

The topic of aging has been studied in scientific literature for a long time.According to research, telomeres, the repetitive nucleotide sequence at the ends of chromosomes, naturally shorten with age, exposing the genetic material contained within the chromosome to damage and leading to impaired tissue regeneration.This damage leads to a variety of negative consequences, such as cellular and tissue dysfunction.Additionally, research indicates that shorter telomeres increase the risk for many of the diseases associated with aging, such as cancer, cardiovascular disease, Type 2 diabetes, and dementia.Ideally, researchers want to identify behavioral changes that will increase telomere length (TL).Some studies have demonstrated that fasting may lengthen telomeres in addition to lowering pro-inflammatory cytokines, and increasing high-density lipoprotein (HDL -good cholesterol) levels.Given the link between fasting and these positive physiological changes, and the wide variation in fasting types and durations, research is needed to determine which fasting types and durations might increase TL.Research indicates that intermittent fasting (IF) in particular has been associated with positive effects on heart health, blood pressure, and weight loss.This study investigated a 68-year-old man using a crossover design in which he served as both the control and test subject over 140 days.During the 70-day control phase of the study, he ate his normal diet with no IF.During the 70-day test phase, he ate during a 12-hour period (a day on), followed by a 36-hour fast (a night, a day off, and another night).He repeated this two-day IF cycle 35 times.Blood was drawn and tested before the control phase, between the two phases, and following the test phase using the 6-Panel Flow Cytometry and Fluorescence in Situ Hybridization (Flow-FISH) TL test.1 Contrary to the study's hypothesis that prolonged fasting without other behavior interventions would lengthen telomeres, the results showed that during the test phase, the subject's TL declined across all six blood-cell types tested.However, during the control phase, the subject's telomeres lengthened in three of six blood-cell types tested, declined in two, and remained unchanged in one.Overall findings of this study suggest that a day-on-day-off IF over 70 days did not increase telomere length and resulted in a decline in TL, which contradicts the study's hypothesis.

Fields of Study & Subjects

Dietary Effects on Health Telomeres Telomerase and Senescence Genetics Aging and Longevity in Model Organisms

Publication details

Publication date
11 January 2026
Document type
Preprint