David Sinclair skips breakfast, eats once or twice a day, and has publicly discussed his fasting approach for years. His Lifespan podcast episode on fasting went viral in 2026. Here's what the actual science says about fasting and aging.
David Sinclair's Lifespan podcast episode on fasting gained tens of thousands of views in its first week of release. The reason is straightforward: Sinclair is a Harvard genetics professor who has been publishing longevity research for 20 years, and fasting is one of the few interventions with reproducible lifespan data across multiple species. When Sinclair discusses it, he's drawing on a specific mechanistic framework that goes well beyond the typical weight-loss framing.
Here is what the science actually says about fasting and aging, why Sinclair's framework is compelling, and what a practical fasting protocol looks like for longevity specifically.
Sinclair's information theory of aging holds that aging is fundamentally a loss of epigenetic information — the cellular "software" that tells genes when to turn on and off. Fasting is, in his framework, one of the most powerful tools for restoring this information by activating the longevity-associated pathways that evolution created for times of scarcity.
The key nutrient-sensing pathways are:
mTOR (mechanistic target of rapamycin): When amino acids and energy are abundant, mTOR promotes cell growth, protein synthesis, and proliferation. When nutrients are restricted, mTOR is suppressed. Lower mTOR activity during fasting triggers autophagy — the cellular cleanup process that breaks down and recycles damaged proteins and organelles. Autophagy is increasingly understood as a core anti-aging mechanism.