peter attia stem-talk

Dr. Peter Attia: Health, Longevity, Finding the Optimal Diet, mTOR, Fasting Glucose, and HA1c – The Diet Doctor Podcast

Check out The Diet Doctor Episode Page & Show Notes

Key Takeaways

  • Just as risk is associated with action, risk is also associated with inaction
  • In life and medicine, strategy > tactics
  • What you eat is important, but so is when you eat and how you cycle your nutrient exposure
  • “I think that the most important thing to consider as a macro-principle of longevity is that the longer you can preserve muscle mass, the better” – Peter Attia
  • mTOR is best activated intermittently (AKA you don’t want it constantly stimulated or always deactivated)
    • How? – Time-restricting your eating and incorporating periodic longer fasts into your routine, followed by periods of feeding
  • Don’t read too much into your fasting blood glucose or HA1c levels – they’re largely unreliable 

Books Mentioned


Peter Attia’s Career Path

  • Studying mathematics & aerospace engineering as an undergrad –>
  • Medical school –>
  • Surgical residency –>
  • Cancer residency –>
  • Cancer surgery fellowship –>
  • Working for McKinsey as a corporate risk consultant —
  • Longevity doctor (and podcast host)

As a longevity doctor, how does Peter think about doing the right thing, without immediate feedback to the outcome?

  • “Everything we do is based on probability; there’s no such thing as absolutes” – Peter Attia
  • You always have to ask yourself:
    • What is the risk of doing X when you can’t ever be certain it will produce the desired outcome?
    • AND – What is the risk of NOT doing X?
      • ^^Most people forget about this one
  • When it comes down to it: “We’re all very lousy at understanding probabilities and risk” – Peter Attia
  • How Peter treats his patients: 
    • 1) Define the objective
    • 2) Develop the strategy (AKA the scaffolding over which you lay the tactics)
    • 3) Bring forth the tactics
    • Peter adds: “Most people in life and medicine miss this middle bucket. They have their objective – to live longer or live better – and they develop the tactics: how to eat, how to exercise, what drugs to take, whether or not to take metformin, etc. … They get mixed up in all these tactical questions.”
      • “I have no interest in these discussions until we’ve established a strategy. I think the strategy for longevity is the single most important pillar for understanding how to practice longevity.”

Peter’s Health Journey

  • Despite being in insanely good health nowadays, Peter used to be pre-diabetic and insulin resistant (check out this old picture of him)
    • (And it’s not like he wasn’t exercising, he was working out a TON)
  • In residency, Peter went vegan for 6 months as an experiment
    • “Many assume people like me wouldn’t find pleasure on a vegan diet. I enjoyed it tremendously. I never met a carb I didn’t like.” – Peter Attia
    • At the end of the 6 months, Peter’s weight had stayed constant and not many blood biomarkers had changed
  • Still suffering weight issues (on top of exercising 28+ hours a week, while working 75-80 hours/week) Peter decided to change things up
    • He first tried removing sugar from his diet (sucrose and high-fructose corn syrup, not sugar from natural foods). Here’s what happened:
      • He experienced a massive drop in his triglyceride levels
      • He lost 10 lbs.
    • The above turned into a long journey, and after several more dietary reductions, in May of 2011 Peter decided to try a ketogenic diet
      • This was right before The Art and Science of Low-Carbohydrate Living came out
      • Peter struggled at first, mainly because of much he was working out
        • “And then something just happened at about the 10-week mark, and I just hit my groove… I don’t understand what it took to switch, but when the switch flipped, I just felt infinitely better.” – Peter Attia
      • Nowadays, Peter advises his patients who have trouble adapting to a ketogenic diet to first try entering ketosis through a short (~3-day) water-only fast
        • This seems to be just enough of a kick to fully deplete the glycogen reserves and upregulate ketogenic enzymes (which allow for the mobilization of fatty acids)
        • “Some of these patients are walking around with a fasting insulin north of 20. It’s REALLY hard to take that person and get them into ketosis [without first fasting].” – Peter Attia

Ditching the Ketogenic Diet

  • Peter spent ~3 years in strict nutritional ketosis
    • During this time, he was logging his ketone levels 2-3x a day
      • Peter says his sweet spot was a morning ketone level of ~1.5 mmol (he averaged 1.73 mmol over the 3 years)
      • You can measure your ketone levels with a Precision Xtra: Use these lancets these test strips
  • “One day decided I was itching for more vegetables… You can eat lots of vegetables on a ketogenic diet, but not at the level that I eat.” – Peter Attia
    • “I just got tired of being pretty restrictive over what I ate”

Will a ketogenic diet allow you to live longer?

  • “I have no earthly clue if someone will be healthier or live longer on a ketogenic diet” – Peter Attia
  • Stop thinking about nutrition and food as diet vs. diet. Instead, think of things on a biochemistry level:
    • All of the food we eat is a combination of carbon, hydrogen, oxygen, nitrogen, sulfur, and a variety of cofactors
    • Food is organic matter that, once metabolized, results in the activation of a bunch of signaling cascades, enzymes, and a variety of hormone pathways
  • To add: “What you eat is part of nutrition, but so is when you eat and when you don’t eat, and how you cycle that nutrient exposure” – Peter Attia
    • One of the key ideas around longevity: Some cyclical exposure to nutrients appears necessary for longevity (AKA temporary periods of calorie restriction or fasting)
    • You can either restrict what you eat (with something like a ketogenic diet) or when you eat (with time-restricted eating)

The Ketogenic Diet & Type 2 Diabetes

  • “It seems a surprisingly high number of patients with type 2 diabetes respond very favorably to a ketogenic diet” – Peter Attia

mTOR | How does Peter thinks about getting adequate protein without overstimulating nutrient sensors?

  • First, some background:
    • mTOR stands for mechanistic target of rapamycin
    • mTOR is activated most potently by the amino acid leucine 
    • When mTOR activity is turned down, through fasting or by supplementing with rapamycin, the body is more likely to undergo autophagy
    • What’s autophagy?
      • Autophagy is the self-eating process where a cell breaks down its own damaged components and remakes them – this is essentially the cell rejuvenating itself
  • “I think that the most important thing to consider as a macro-principle of longevity is that the longer you can preserve muscle mass, the better” – Peter Attia
    • Certainly, at some point, too much muscle mass can be counterproductive to longevity (i.e., if you’re a bodybuilder who weighs 340 lbs.)
    • In the last decade of a person’s life, muscle loss accelerates and becomes quite problematic – this causes a very high number of deaths to result from accidental falls
    • “What’s the best way to avoid muscle loss? Maintain muscle as long as possible, starting in your youth.” – Peter Attia
  • Having mTOR always in a low (deactivated) state isn’t optimal
    • If you’re constantly protein malnourished or calorically restricted, you’ll always have a low level of mTOR activity 
      • Therefore: “Constant caloric restriction, in the long run, probably is a wash or may even be harmful” – Peter Attia
      • Constant mTOR deactivation is definitely protective of things like cancer, but definitely not for maintaining muscle mass
    • This being said, you definitely don’t want mTOR constantly stimulated either
  • What can be done?
    • You need a cyclical approach: incorporate time-restricted eating and periodic longer fasts into your routine, followed by periods of feeding
      • This will result in intermittent mTOR activation

Peter’s Thoughts on the Carnivore Diet

  • It definitely works for some people, particularly those with autoimmune issues
    • “But one has to be careful because the cheerleaders are the ones you’re hearing the most. You don’t get to see what the graveyard looks like for all the people who tried a carnivore diet and didn’t have favorable results.” – Peter Attia
  • “On first principles, a lifetime of following a carnivore diet strikes me as not particularly healthy” – Peter Attia

Fasting Glucose and HA1c | Why Neither Are Reliable Biomarkers

  • For background: HA1c is a marker for your long-term average blood glucose level
  • Peter wears a Dexcom G6 continuous glucose monitor (CGM)
  • “Ever since I’ve been wearing a CGM, my interest in HA1c, as an absolute number, and fasting glucose has gone from marginal to negative. I think those are categorically two of the dumbest things we measure, and worse yet, make treatment decisions based on.” – Peter Attia
    • Why?
      • Peter is a beta-thalassemia carrier (he has one copy of the gene)
      • As a result, he has 50% more red blood cells than an average person (but they’re much smaller)
      • As a secondary result, Peter’s glucose is never as high as his HA1c indicates
      • Peter explains why:
        • “There’s an underlying principle that goes into HA1c, which is the life of the red blood cell. When a person has a red blood cell that sticks around longer than the prediction based on the algorithm, the measured HA1c leads to an imputed value of glucose that’s much higher than is true.”
          • AKA HA1c overestimates average glucose
        • The reverse is also true: If someone has red blood cells that tend not to stick around as long as they should, their HA1C will measure lower than what their imputed level of glucose is
          • AKA HA1c underestimates average glucose
  • In terms of fasting glucose:
    • It’s mostly meaningless because of the impact cortisol has on it
      • Peter has noticed that when he’s stressed or hasn’t been sleeping well (thus, his cortisol levels are high) his fasting glucose levels are raised
      • Why is this the case? – Cortisol increases hepatic glucose output (HGO)

Peter’s Current Fasting, Diet, & Exercise Routine

  • CAVEAT: “No one should be doing what I’m doing unless they can demonstrate that they’re similar to me in some way in terms of where they are, what they want, and what their appetite for risk is” – Peter Attia
  • Peter’s Routine:
    • Every quarter, he does a 7-day water-only fast (AKA shutting off mTOR) sandwiched by a week of following a ketogenic diet on each end 
    • He time-restricts his eating when he’s not fasting or following a ketogenic diet
      • On Mondays, Wednesdays, and Fridays (when he lifts weights) his eating window is ~10 hours
      • On Tuesdays, Thursdays, Saturday, and Sunday (when he does cardio work) his eating window is ~4-6 hours

Fasting’s Effect on Fitness

  • Peter has noticed that during his water-only fasts his leg speed seems to drop (he can’t keep up a high RPM on his Peleton)
    • Even walking feels difficult to him
    • “Conversely, being in the weight room, I seem to experience no deficiency in strength … But I need much longer to recover between sets.” – Peter Attia 

Additional Notes

  • “I absolutely consider the 1-hour postprandial (post-meal) insulin to be one of the most important numbers I can get from a patient” – Peter Attia
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Notes By MMiller

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