Extended Fasting
Episodes covering extended fasting — protocols, research, and expert discussions.
Prolonged water fasts lasting 24-72+ hours to trigger deep autophagy, metabolic reset, stem cell regeneration, and potential longevity benefits beyond what time-restricted eating provides
Extended fasting (24-72+ hours) goes beyond daily time-restricted eating to trigger deeper cellular processes. The science is compelling: autophagy (cellular cleanup) ramps up significantly after 24 hours, ketosis deepens, and at 72+ hours, studies suggest stem cell regeneration begins. Valter Longo's research on fasting-mimicking diets has brought mainstream credibility to periodic extended fasts.
A 24-48 hour water fast 1-4 times per month is reasonably safe for healthy adults and can provide meaningful metabolic and cellular benefits. Fasts beyond 72 hours require more caution and ideally medical supervision. Start with shorter fasts and work up gradually. The discomfort is front-loaded - most find days 2-3 easier than day 1.
Science & Mechanisms
Mechanisms:
- Autophagy - Cellular recycling process that degrades damaged proteins and organelles
- Ketosis - Shift from glucose to fat/ketone metabolism
- Stem cell regeneration - Longo's research shows immune system regeneration at 72+ hours
- Insulin sensitization - Extended fasting resets insulin signaling
- mTOR inhibition - Nutrient-sensing pathway downregulation promotes longevity
- AMPK activation - Cellular energy sensor that triggers beneficial adaptations
- Growth hormone surge - HGH increases to preserve muscle during fasting
Key concepts:
- Autophagy begins around 16-24 hours and deepens with duration
- Full ketosis typically achieved by 24-48 hours
- Stem cell activation observed around 72 hours in animal models
- Refeeding phase is critical - triggers regeneration and rebuilding
- "Fasting-mimicking diet" (FMD) can provide some benefits with easier compliance
Evidence base:
- Valter Longo's USC research: FMD cycles reduce cancer risk markers, IGF-1, inflammation
- Buchinger Wilhelmi clinic data: Thousands of supervised fasts showing safety and efficacy
- Animal studies: Consistent lifespan extension with periodic fasting
- Human RCTs: Limited but growing, showing metabolic improvements
- 2019 Cell Metabolism study: 10-day fast improved cardiovascular markers
Limitations:
- Most robust data from animal studies - human research still limited
- Long-term effects of repeated extended fasts unclear
- Individual variation in response is significant
- Refeeding syndrome risk with very long fasts
- May not be suitable for all populations
Episodes
Gary Brecka joins The Ultimate Human with Gary Brecka to discuss how to start water fasting today: benefits, types and who should avoid it. Key topics include protocols and timi...
Dr. Dominic D'Agostino is a tenured associate professor at USF and researcher at the Institute for Human and Machine Cognition. This updated conversation covers the latest on ke...
Rhonda Patrick answers questions about fasting, covering different fasting protocols, their benefits, and how to implement them safely and effectively.
True autophagy requires about 5 days of water fasting to cut IGF-1 by 50%, but fasting-mimicking compounds like resveratrol and spermidine can trigger similar pathways. Exercisi...
Dave Asprey joins The Human Upgrade to discuss what if you stop eating for 72 hours? : 1375. Key topics include nutritional strategies based on current research; performance opt...
Dave Asprey sits down with Christian Drapeau, a neuroscientist and stem cell researcher from McGill University, to explore why stem cell decline is a core driver of aging, fatig...
Sean McCormick delivers a solo episode announcing his "Dry Fast With Friends" program, drawing on his personal experience completing a five-day dry fast. He describes how he fir...
Metabolic switching from glucose to ketones kicks in after roughly 10 hours of fasting, triggering protective cellular pathways. Fasting increases BDNF production to support bra...
Gary Brecka sits down with Kelly Slater, the 11-time world surfing champion who dominated professional surfing from age 20 into his 50s. The conversation explores the biohacking...
Anthony William, known as the Medical Medium, dedicates this radio show archive episode to examining different types of fasting including water fasting, intermittent fasting, ju...
Evolutionary biologists Bret Weinstein and Heather Heying reveal that they completed a seven-day dry fast, consuming no food or water for an entire week. They recorded their pre...
Dr. Nadia Pateguana discusses the benefits and potential side effects of fasting, with a focus on intermittent fasting. She addresses the ongoing debate about fasting's effects ...
Dave Asprey speaks with Dr. Theodore Achacoso, founding pioneer of Health Optimization Medicine, and Boomer Anderson, CEO of Troscriptions, about aging as a cellular and metabol...
A detailed hour-by-hour breakdown of what happens in your body during an extended 100-hour fast. Dr. Jockers explains the metabolic shifts, autophagy activation, and physiologic...