Podcast Summary: The Tim Ferriss Show #825

Guest: Dr. Dominic D’Agostino
Host: Tim Ferriss
Date: September 3, 2025
Topic: All Things Ketones – Brain Protection, Cognition, Sardine Fasting, Diet Rules, Metformin, Melatonin, and More

Episode Overview

Tim Ferriss sits down with Dr. Dominic D’Agostino, a renowned researcher and professor in molecular pharmacology and physiology, to dive into cutting-edge research and personal experimentation on ketogenic diets, exogenous ketones, metabolic therapies for brain function, cancer, and much more. This conversation covers practical applications, latest science, personal routines, supplement protocols, equipment recommendations, and “sardine fasting.” The episode delivers actionable insights for listeners aiming to optimize brain health, longevity, and metabolic performance.

Key Discussion Points & Insights

1. Ketones: What They Are & Why They Matter

• Types of Exogenous Ketones: Ketone salts vs. esters; BHB (beta-hydroxybutyrate) as the primary measurable ketone (00:40).
• Stacking Strategy: Combining BHB with MCT oil raises circulating ketone levels more effectively and sustains elevations (01:45).
  • "Exogenous BHB plus MCT increases BHB higher than either one taken alone. MCT sustains the elevation by slowing absorption." — Tim, summarizing Dom (01:50)
• Beyond Fuel: Ketones act not just as an energy source but as signaling molecules/hormones, influencing antioxidant and cellular defense pathways (02:40).
• Anti-inflammatory Effects: Ketones directly inhibit the inflammasome, which is implicated in chronic, age-related diseases—independent of their role as a fuel (04:00).
• Cancer & Neurology: Research and anecdotal evidence suggest therapeutic applications of ketogenic strategies in Alzheimer’s disease and certain cancers (02:50–05:50).

2. Safety, Risks, and Best Practices around Ketone Supplements

• Liver Toxicity & Chronic Use: 1,3-butanediol–based ketone esters—frequently sold as supplements—may have liver toxicity when used long-term above 100mL/day. Cycling off and moderation are key (05:20).
• Transitioning Away From 1,3-Butanediol: More supplement companies are pivoting due to these safety concerns (07:20).

3. Practical Ketone Applications

• Soluble Fiber & Natural Ketosis: Certain fibers (e.g., artichokes) ferment into butyrate—an endogenous ketone; cows are naturally ketotic (08:00).
• Ketones & Hyperbaric Oxygen Therapy (HBOT): Taking exogenous ketones before HBOT can mitigate oxygen toxicity and enhance recovery (08:20).

4. Sardine Fasting & Diet Rules

• Sardine Fasting Origin: Dr. Fred Hatfield (aka Dr. Squat) used a “sardine fast”—one can of sardines per day for a week each month—to extend his life following a metastatic prostate cancer diagnosis (25:09–28:03).
• Rationale: Provides nutrition, omega-3s to prevent cachexia, and triggers similar physiological effects (caloric restriction, autophagy) as water fasting without muscle loss (31:55).
• Dom’s Usage: Sardine fasting seen as superior or at least equivalent to water fasting for most benefits, without dangers of cachexia (31:55–33:08).

5. Fasting, Ketogenic Diet, Exogenous Ketones—What’s Different?

• Fasting: Drives autophagy and “cellular cleanup.” Dom deploys it situationally, not routinely. He avoids full water fasts to prevent muscle loss (29:55–31:53).
• Ketogenic Diet vs. Exogenous Ketones: Diet triggers endogenous ketone production and full metabolic adaptations, whereas exogenous ketones provide acute effects but do not drive full metabolic remodeling (23:12–24:27).

6. Practical Tools: Measuring and Tracking

• Keto Mojo vs. Precision Xtra: Keto Mojo recommended for at-home ketone/glucose monitoring; good accuracy, helpful GKI (Glucose Ketone Index) calculation (22:03).
• Importance of GKI: Target ranges of 1–4 (optimal: 1–2) suggest beneficial ketosis; typical Americans have much higher GKI (40:38–42:44).

7. Diet Implementation, Personal Routines, and Troubleshooting

• Dom’s Eating Pattern: About 3 meals daily; breakfast: eggs and mackerel; lunch/dinner: beef, chicken, or fish, plus lots of broccoli or wild berries (64:11–67:36).
• Tips for Easier Adaptation:
  • Fasted low intensity cardio (morning walks)
  • Stay hydrated; prioritize electrolytes
  • Supplement with MCT oil and low-dose exogenous ketones (69:20–71:14)
• MCT Usage: Both liquid and powder forms; powder easier for travel (73:31)
• Wild Blueberries/Local Food: Wild blueberries are better than large farmed blueberries; available at many supermarkets (44:48–45:20).

8. Supplements & Medications Discussed

• Go-To Supplements:
  • Creatine monohydrate (for cognitive & physical health, 10–20g/day for Alzheimer’s, if tolerated)
  • Vitamin D (check labs; aim for 60–80ng/mL)
  • Melatonin (neuroprotective, no clear evidence for human endocrine disruption; 5–10mg, sometimes even 20–30mg)
  • Omega-3s (sardines preferred, or high-quality supplement like Nordic Naturals)
  • Exogenous ketones (emerging data for use in cognition, brain health)
  • GABA/magnesium/low-dose diphenhydramine for fasting-related sleep issues (55:37)
• Metformin: Used as an adjunct in some cases (especially for glucose regulation and cancer), but Dom reports “mild liver toxicity, lactic acidosis, sun sensitivity” as side effects (88:27–89:46).
• Berberine: Natural alternative to metformin; Dom experiences headaches with prolonged use (91:44–93:46).
• GLP-1 Drugs (e.g., tirzepatide): Game changing for glucose regulation and possibly neuroprotection (92:44–94:02).

9. Neurodegeneration & Metabolic Psychiatry

• Alzheimer’s and Beta-Hydroxybutyrate:
  • Deficient glucose metabolism central to Alzheimer’s (“type 3 diabetes”)
  • Ketones can rescue impaired brain energy metabolism
  • Inflammation, infections (e.g., HSV, Epstein-Barr) may be root causes/scaling factors for dementia (16:13–20:28).
• Metabolic Psychiatry: Emerging research on ketogenic metabolic therapies for bipolar disorder, depression, ADHD, and anxiety (79:18–81:39).
  • App Recommendation: Metsci (metpsy.com)—a coaching and tracking app for metabolic psychiatry (81:32).
• Mood Impact: Ketosis can reduce anxiety up to a point (1–2 mmol/L optimal for calm/focus); above that, anxiety may increase (86:03).
  • “There seemed to be a sweet spot, maybe 1 to 2, I wouldn’t go above 3… That seems a level that safely does not produce metabolic acidosis.” — Dom (86:04)

10. Hyperbaric Oxygen Therapy (HBOT)

• Therapeutic Role: Used for cognitive impairment post-TBI and in adjunct with cancer treatments (107:02–109:41).
• Research Ongoing: Large-scale studies in veterans (USF, Moffitt Center); ketone therapy may enhance HBOT benefits and safety (108:45).

Notable Quotes & Memorable Moments

• On Ketones as More Than Fuel:
  “Ketones can be thought of as hormones in a sense, or at least signaling molecules.” — Tim Ferriss (02:40)

• Sardine Fasting for Cancer:
  “Fred [Hatfield] would do like one or two cans of sardines, maybe one per day for a week. …He went into rapid remission and the doctors didn’t really know… Fred ended up passing away maybe eight years later of something completely unrelated to his cancer.” — Dom D’Agostino (25:09–26:15)

• On Melatonin:
  “I’ve been using melatonin probably when I started using creatine in 1993… There was no evidence in human [of endocrine suppression]… I measured that. I also confirmed that 5 mg of melatonin… the next day in the morning, my melatonin is off the charts.” — Dom D’Agostino (56:04–57:53)

• On Adapting to Keto:
  “Low intensity cardio, hydrate, get in electrolytes, and also elevate ketones as much as possible… with MCT if you can tolerate it.” — Dom D’Agostino (70:36)

• On Measuring Ketones:
  “Keto Mojo… consistently gives us numbers that are more in line with our biological assays that we run in the lab.” — Dom D’Agostino (22:03)

Important Timestamps

• 00:40 — Introduction to different forms of ketone supplements
• 01:45 — Stacking ketones with MCT for synergistic effect
• 08:00 — Fiber (artichokes), fermentation, and ketosis in cows
• 22:03 — Ketone/glucose tracking devices: Abbott Precision Xtra vs. Keto Mojo
• 25:09 — Dr. Fred Hatfield and the origins of sardine fasting
• 31:55 — Omega-3s in sardine fasting prevent cachexia
• 44:48 — Importance of fiber, wild berries, broccoli in Dom’s diet
• 55:37 — Dom’s sleep stack for fasting: GABA, melatonin, low-dose diphenhydramine
• 62:00–68:00 — Dom’s daily meal structure and rationale
• 69:20 — Tips for transitioning into ketogenic state
• 79:18–81:39 — Metabolic psychiatry as an emerging discipline
• 107:02–109:41 — Overview of major HBOT study in trauma and potential for synergy with ketones

Additional Resources/Links (mentioned by guest/host)

• Ketonutrition.org — Dom’s informational website
• Metabolic Health Initiative/Summit — Medical education platform
• Audacious Nutrition Keto Start — Exogenous ketone supplement used in research
• Metpsy.com — Metabolic psychiatry lifestyle and treatment app
• Metsci, Metabolic Mind — Education and research organizations
• Levels — CGM and metabolic tracking (levelshealth.com)
• Keto Mojo — Affordable at-home glucose/ketone meter

Conclusion

This episode is dense with actionable details, nuanced biochemical explanations, and pragmatic experimentation—all delivered in a lively, accessible style. Dr. D’Agostino and Tim Ferriss cover advanced metabolic therapies for brain health, practical steps for optimizing ketosis, supplements, diet composition, new tech and devices, and potential therapeutic applications ranging from Alzheimer’s to cancer and psychiatric disease. The recommended “stack” protocols, discussion of sardine fasting, warnings on certain supplements, and the focus on measurement/lab tracking provide listeners with a comprehensive toolkit for implementing their own experiments in metabolic health.

This summary provides a comprehensive map of the episode’s most valuable insights, quotes, and takeaways, suitable for newcomers and seasoned biohackers alike.