8. Peter Attia: “I Definitely Lost a Lot of IQ Points That Day”

Summary

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Podcast Summary: People I (Mostly) Admire — Episode 8

Guest: Peter Attia
Host: Steven Levitt
Date: February 21, 2026

Overview

This episode features Steven Levitt in a candid, wide-ranging conversation with Dr. Peter Attia, a physician, endurance athlete, longevity expert, and podcaster. Attia shares his unconventional life journey—boxing, medicine, management consulting, and the obsessive self-experimentation that defines his approach to health and longevity. The discussion dives deep into Attia’s views on nutrition, fasting, exercise, personal change, and even COVID policy, all delivered with his trademark rigor and intensity.

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Key Topics and Discussion Points

1. Peter Attia’s Unconventional Path and Self-Experimentation

• Early ambitions: Attia describes his teenage obsession with becoming a professional boxer, detailing a relentless training schedule that started at 5 a.m. and included multiple workouts a day ([03:52]).
  • “I missed that routine once in four years.” — Peter Attia ([04:52])
• Academic rigor: His approach to academics mirrored his athletic discipline, driven by insecurity and fear of not being "good enough" ([06:37]).
  • “That work ethic came from this belief that … if anybody knew how bad I was at this, it would be embarrassing.” — Peter Attia ([06:54])
• Medical career and departure: After medical school and a surgical residency at Johns Hopkins, Attia left medicine—citing frustrations with unmeritocratic systems and resistance to quantitative innovation—eventually joining McKinsey ([07:45]).
  • “It wasn’t one thing … it was about 10 things.” — Peter Attia ([07:45])

2. Reflection and Major Life Transitions

• Navigating change: Attia credits hitting low points (“local minima”) in life as important catalysts for change, emphasizing luck and supportive relationships ([10:28]).
  • "You need to hit a local minima in life to make a change, if not an absolute minimum." — Peter Attia ([10:34])
• Letting go and evolving values: He shares that he now accomplishes less, but it’s a trade-off for a more meaningful and sustainable life ([10:47]).

3. Obsessions with Nutrition, Sleep, and Self-Improvement

• Motivation for change: The birth of Attia's daughter and a cardiovascular scare prompted his deep dive into nutrition and longevity ([11:50]).
  • “Whatever genes killed everyone before you are coming for you if you don’t do something about it.” — Peter Attia ([12:17])
• The challenge with nutrition: He notes the lack of nutrition education in medical school and the confusion in public dietary guidelines ([11:50]).

4. Rapid-Fire Health Topics and Attia’s Current Stances

Nicotine

• Cognitive and metabolic effects: Attia describes non-smoking uses of nicotine (e.g., Nicorette gum) for mental sharpness and fat metabolism, lamenting its association with cigarettes ([13:29]).
  • “I think nicotine is a remarkable molecule, and it’s unfortunate that … it was typically packaged with … cigarettes.” — Peter Attia ([14:27])
• Levitt’s self-experimentation: Levitt recounts unsuccessfully using Nicorette to stay alert in academic seminars ([14:42]).

Sleep

• Transformational appreciation: Attia admits to neglecting sleep for years in residency, later realizing its critical role in metabolic health and longevity ([15:55]).
  • “... my testosterone was, you know, slightly higher than that of a prepubescent girl. Everything was metabolically broken.” — Peter Attia ([16:19])
• Fasting, Naps, and Productivity: Attia discusses emerging evidence on restorative napping and the complex science of sleep cycles ([18:19]).

Sugar

• Continued skepticism: Attia remains highly critical of added sugars (especially fructose and high-fructose corn syrup), noting their profound evolutionary mismatch and metabolic harms ([20:48]).
  • “... eating a diet that’s high in fructose … wreaks all sorts of metabolic destruction.” — Peter Attia ([22:19])
  • Memorable moment: When ordering at a restaurant, he once told a waitress, “I die,” when asked about his “allergy” to sugar ([22:50]).

Ketosis and Fasting

• Evolutionary advantage & modern utility: Ketosis is explained as a metabolic adaptation for brain energy; Attia discusses his periodic fasting routines and clarifies the difference between nutritional and starvation ketosis ([23:39]).
  • “I did at one point … spend three years in uninterrupted nutritional ketosis.” — Peter Attia ([25:27])
  • “These days … I fast frequently. So either three days a month or seven days a quarter.” — Peter Attia ([25:52])
• Benefits: Fasting triggers autophagy, reduces risk for chronic diseases, and potentially extends quality life-years ([26:09]).
• The unknowns: We lack precise data on the optimal “dose” of fasting for maximum health benefits—a potentially solvable research challenge ([27:09]).

Longevity

• Estimated gains: Attia believes optimal health behaviors could extend life by 5-15 years, especially improving the quality of the last decades ([28:16]).
  • “But what’s more important … is what’s the quality of those last 20 years?” — Peter Attia ([28:35])
• Philosophy on mortality: Attia would decline immortality, emphasizing the emptiness of outliving everyone you love ([30:02]).
  • “… there is, to me, no upside in outliving everyone that matters to you. And so I think death is a very important part of the carbon cycle.” — Peter Attia ([30:17])

5. Critique of COVID Policy and Preparedness

• Disappointment with public health response: Attia faults the U.S. for not running quick, meaningful experiments during COVID, missing chances for crucial knowledge ([30:47]).
  • “Why weren't we immediately engaging in a whole bunch of experiments that would very rapidly get us answers …?” — Peter Attia ([31:06])
• Systemic inertia: Both he and Levitt criticize the US medical and research systems for risk aversion and lack of proactive, incremental learning ([31:22]; [35:09]).
• The importance of future planning: Attia is involved in privately funded long-term immunity studies; he advocates for philanthropy to de-risk ambitious research before government backs it ([34:19]).

6. Reflections on Life, Change, and Parenting

• Advice to young people:
  • Reflect on your drives and insecurities.
  • Don't let sunk costs trap you into stale careers—change is good ([36:56]).
  • “Life isn’t really about necessarily being the master of something.” — Peter Attia ([37:32])
• On quitting: Both agree that flexibility and the willingness to let go are undervalued virtues ([38:05]).
  • “Rigidity of thinking is generally a bad thing.” — Peter Attia ([38:05])
• Parenting philosophy:
  • Attia shares doubts about preparing his children for an uncertain future but emphasizes critical thinking, open-mindedness, and exposure to uncomfortable ideas ([38:54]).
  • Memorable story: Substituting Mystery Science Theater 3000 with a Noam Chomsky documentary to inspire analytical thinking in his daughter ([39:50]).
  • “You should be in the habit of listening to people talk about stuff that you don’t agree with.” — Peter Attia ([40:18])

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Notable Quotes & Moments

• On insecurity as a driver:
  “I think the whole boxing thing came from an insecurity. And that work ethic came from this belief that … I’m not good enough.” — Peter Attia ([06:54])

• On concussions and boxing:
  “I definitely had one horrible concussion … I’ve definitely lost a lot of IQ points on that day.” — Peter Attia ([05:27])

• On change and minima:
  “You need to hit a local minima in life to make a change, if not an absolute minimum.” — Peter Attia ([10:34])

• On nicotine’s misunderstood benefits:
  “I think nicotine is a remarkable molecule, and it’s unfortunate it was … packaged with cigarettes.” — Peter Attia ([14:27])

• On sleep deprivation:
  “When I finished residency, if you looked at a blood panel of mine, you would never imagine that I was a 33 year old.” — Peter Attia ([16:11])

• On sugar:
  “There’s something about that fructose molecule that is really problematic … eating a diet that’s high in fructose … wreaks all sorts of metabolic destruction.” — Peter Attia ([22:11])

• On mortality:
  “There is, to me, no upside in outliving everyone that matters to you. And so I think death is a very important part of the carbon cycle.” — Peter Attia ([30:17])

• On public health and COVID:
  “Why weren't we immediately engaging in a whole bunch of experiments that would very rapidly get us answers to questions that would enable us to decide what to do?” — Peter Attia ([31:06])

• On thinking and parenting:
  “You should be in the habit of listening to people talk about stuff that you don’t agree with. … By listening to this guy talk about subjects … he’s sharpening my point of view and sometimes changing my point of view.” — Peter Attia ([40:18])

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Timestamps for Key Segments

• Boxing and adolescence: 03:52–06:25
• Academic drive and insecurities: 06:37–07:39
• Leaving medicine for McKinsey: 07:45–09:27
• On major life change and minima: 10:15–11:43
• Nutrition and longevity journey: 11:43–12:41
• Nicotine’s pros and pitfalls: 13:29–14:42
• Sleep science and personal experiments: 15:43–17:59
• Napping, productivity, and modern research: 18:19–20:09
• Sugar and metabolic disease: 20:43–23:39
• Ketosis, fasting routines, and benefits: 23:39–27:53
• Added years and quality of life: 28:16–30:02
• Musings on immortality and loss: 30:02–30:30
• COVID policy critique: 30:30–34:34
• Research funding and innovation barriers: 34:34–36:56
• Advice on change and quitting: 36:56–38:43
• Parenting and raising thinkers: 38:54–41:31

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Tone and Style

• Open, humble, deeply introspective: Attia frankly acknowledges both his strengths and foibles.
• Intellectually curious and non-dogmatic: Both host and guest admire the willingness to change one’s mind.
• Humor and vivid anecdotes: The interview is peppered with self-deprecating humor and memorable stories.

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Conclusion

This episode delivers an honest, engaging window into the restless mind of Peter Attia. From boxing rings to surgical suites, consulting firms to podcast studios, Attia’s journey exemplifies radical change built on relentless questioning and personal experiment. For listeners, the episode offers practical health advice, nuanced critiques of science and policy, and deeply human reflections on change, meaning, and raising resilient kids.

Transcript

[Peter Attia]

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[Peter Attia]

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[Peter Attia]

If I'm proudest of anything I've done in my life, it's that every time I've made a change that has looked really stupid, I've always been able to think that, you know, it's okay because I'm going to be 60 one day. I might as well be 60 doing what it is I love at the time I'm 60 as opposed to what I should be doing because I trained for it. For all these other times

[Steven Levitt]

if I were really sick. Peter Attia is who I'd want for my doctor. I've known Peter for 10 years. He's one of the most intelligent, curious, compassionate people I've ever met, but I have to say he's also completely totally insane.

[Peter Attia]

Welcome to People I Mostly admire with Steve Levitt.

[Steven Levitt]

The set of things he's done to his body over time in the spirit of self experimentation are mind blowing. I rarely have a conversation with Peter in which he doesn't introduce me to something I've never thought about before. He is willing to entertain any hypothesis and I will say he's one of the few people who, when he tells me to do something, I just do. Is such a pleasure to be talking today with my good friend Peter Attia, physician, endurance athlete, longevity expert, podcaster, and honestly one of the least predictable and most intelligent people I've ever met. So I want to start with a story. I don't know if you remember the first time we met, but we were at dinner and it must have been just after your birthday because you were glowing and you said, oh my God, I got the best birthday present ever for my wife. And just to jog your memory, I. She'd given you some kind of equipment that allowed you to prick your finger and do blood tests. You remember what I'm talking about?

[Peter Attia]

Yes. It was a lactate meter that she got me to be able to prick my finger while riding my bike and swimming or running or whatever.

[Steven Levitt]

So the goal was that you wanted immediate feedback on what was going on inside your body as you did these extreme workouts that you are prone to do.

[Peter Attia]

Yeah, yeah.

[Steven Levitt]

And I asked you, well, how do you know when it's time to stop working out? He said, either when I lose consciousness or when I piss or crap myself. That's when I decide I've worked out hard enough.

[Peter Attia]

I've come a long way since then, Steve. I don't do such silly things anymore. Now that I'm concerned with longevity, that type of working out is totally unnecessary.

[Steven Levitt]

All right, so let's talk about your very unusual background. So you went to Stanford and got your medical degree there, and the. Then you did your residency at Johns Hopkins. You went to McKinsey. But you started out wanting to be a professional boxer, right? Yeah. So tell me about when you were 14 and you wanted to be a professional boxer. What did your day look like?

[Peter Attia]

It was hard, actually. It started very early. I would be up at five o' clock every morning. I would run between five and 13 miles each morning. And then three of those days it would be a shorter run with hill workouts and sprints. And then I would go to the gym and. And do an hour workout. Before that was mostly rowing machine and skipping. And then at lunch, we would go to the University of Toronto. I grew up in Toronto, so we'd go to University of Toronto's weight room and do our really heavy lifting. And then after school, I would get home and then do another 90 minutes of work on the heavy bag, speed bag, double end bag in my basement, coupled with more sort of anaerobic training. And then in the evening would be going to the gym for sparring. And then I would come home and I had a ritual that I would do 400 pushups every single night in sets of, like, 50s, and then go to bed and repeat. And I missed that routine once in four years.

[Steven Levitt]

That's intense. Were you a good fighter? Were you a good boxer?

[Peter Attia]

I mean, I was a pretty good fighter at the time, but we have a heavy bag in our garage now, and I am so humbled by how bad I am now. It gives me a greater respect For a sport that I once did that I didn't even have at the time yet. You know, you sometimes need that distance from something. I'm sure anyone who did something at a high level, whether it be playing the piano or doing anything once, they're so far past their prime, they look back and go, you know, I don't think I appreciated what it took to get there.

[Steven Levitt]

And did you actually do a lot of fights? Did you get hit a lot in the head?

[Peter Attia]

I did. Of course. This is now a very hot topic today. We care about this. I definitely had one horrible concussion. How many other concussions I had, I don't know. But there was a brutal concussion I had and a guy who was one weight class above me, and quite frankly, at that point, a better fighter. I mean, he just landed a right cross on the side of my head that at the time, I didn't think anything of. We finished the round, but something inside said, you don't feel right. So I said, hey, Mike, I gotta call it a day, man. And when I went down to cool down by hitting the speed bag, which is that tiny little round bag that basically has no weight or impact, just the impact of hitting, that hurt my head so much that I was like, I gotta stop, you know, I ended up having a CT scan a couple days later. It showed I had cerebral contusions. I basically had the worst headache of my life. For the next three months. I could barely turn my head. So, yeah, I've definitely lost a lot of IQ points on that day.

[Steven Levitt]

Well, it sounds like you ended up making the right career choice. So you took more or less the same approach to academics that you took to boxing. Can you describe how you approached your undergraduate classes at Stanford?

[Peter Attia]

Well, my undergrad was actually in Canada, which is where I did math and engineering. My med school was at Stanford. But I think there was a very similar insecurity. Right. So I think the whole boxing thing came from an insecurity. And that work ethic came from this belief that I actually don't think is that healthy. It comes from this place of, I'm not good enough. If anybody knew how bad I was at this, it would be embarrassing. I'll give you one example. I think once I was in medical school and I decided I wanted to become a surgeon, I just had this anxiety, which was, well, what if you have to operate in the middle of the night and you're tired? So one of the things I started doing in my last year of medical school was every Thursday night I would stay up Pull an all nighter, stand at my desk, not allow myself to pee, and practice suturing on my desk in this model that I made that was supposed to resemble like a human heart. And, you know, it was very uncomfortable, but it was like, you got to do it, man. You got to do it.

[Steven Levitt]

And did that pay off when you went to surgery?

[Peter Attia]

I don't know if that exercise did, but yes, I think a lot of the training that I did did pay off, actually.

[Steven Levitt]

And so why did you end up leaving surgery to go to McKinsey of all places?

[Peter Attia]

So there were a lot of things that were really upsetting me at the time. Residency didn't seem very merit based. That sort of irked me. Also, I had a big fight with one of the physicians at Hopkins who's super respected and amazingly prominent. And to this day, we still respect each other greatly. But I tried to build a mathematical model to address a problem in the ICU that was typically done by putting your finger in the air and, you know, sort of looking at which way the wind blows. And actually, my model ended up working really well, but I was basically threatened that I'd be fired if I ever did it again. So it wasn't one thing, Steve. It wasn't. It was about 10 things. And so when I decided to leave, my first thought was actually go to business school, because I really missed doing quantitative problem solving. And it was at that point that I learned about this company called McKinsey that was kind of like business school that you got paid for. And that seemed like a better option given that I was already sitting on $200,000 worth of debt. So that's how I ended up at McKinsey. You're listening to people I mostly admire with Steven, Steve Levitt and his conversation with physician and scientist Peter Attia. They'll return after this short break. With Venmo Stash. A taco on one hand and ordering a ride in the other means you're stacking cash back. With Venmo Stash, get up to 5% cash back when you pick a bundle of your favorite brands. Earn more cash when you do more with Stash. Venmo Stash terms, exclusions apply. Max $100 cash back per month. See terms At Venmo Me Stashterms, we know you'll always find ways to look out for the people you love.

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[Peter Attia]

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[Peter Attia]

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[Steven Levitt]

I can't think of many people who have reflected on their life as effectively as you have, especially successful people, and been able to rewrite it. Do you recognize that in yourself?

[Peter Attia]

Well, I think it's too soon to say that. I am absolutely in the process of rewriting it, and that is my intention. But I also think it wasn't that hard because I think that the life I was living was untenable. You need to hit a local minima in life to make a change, if not an absolute minimum.

[Steven Levitt]

And.

[Peter Attia]

And I think the people who are luckiest, and I put myself in that category, hit local minima, recognize they've hit a local minima, but not so much damage has been done that they can't get out of it. So I don't know that I really deserve any credit. It's a bit of luck, and it's having really good people around me who are really patient, who have been able to help nurture me back to a new way of thinking about life that is unrecognizable compared to the easy ethos that was 10 years ago. But it also comes with letting go of a bunch of stuff, too, right? It comes with just accepting the fact that I do not accomplish as much today as I used to, and there's no getting around that. And there's days when that really hurts. There's days when I really feel like I'm getting left behind and the train is so far ahead and I'm never going to catch up. But we just have to know what we're doing it for and what matters.

[Steven Levitt]

And then you became obsessed with nutrition, right? When I first met you, that was your obsession, was nutrition.

[Peter Attia]

Well, I think there's something kind of biologically interesting that happens in people when they have a kid, which is they sort of realize their own mortality, in a way. And when my daughter was born, I ended up getting a type of medical test that had a finding that no one in their mid-30s should have. And it's a finding that basically predicts, you know, early onset of cardiovascular disease, which shouldn't have been a surprise to me, because the List of men in my family who have died of cardiovascular disease is pretty long. So this just reinforced in me that you're not immortal. And by the way, whatever genes killed everyone before you are coming for you if you don't do something about it. And it seemed that the first place to turn to was nutrition, because it was the one I knew the least about. We certainly didn't learn anything about it in med school. It's also the one that seemed the most conflicted.

[Steven Levitt]

I will say that you've taught me a lot. And I've never told you this before. You're one of the few people on the planet whose opinion I trust so completely that when you tell me to do something, no matter how absurd it sounds, I do it. And that's really about the highest praise I can offer anyone.

[Peter Attia]

I know.

[Steven Levitt]

You know, we talk once every six months or four months, and you'll tell me your latest thing, and I religiously do whatever you tell me to do. And then we talk six months later. That's a distant memory for you. You've decided that was a terrible idea. And so for six months, I've been doing something that was probably a really bad idea as well. But I love that about you, that you're willing to change your mind. So, in the spirit of you changing your mind, I'd love to just toss out a couple topics and you tell me what your current thinking on those. So how about nicotine? What's good about nicotine?

[Peter Attia]

Well, I mean, I think it definitely has some cognitive sharpening capacities. I think most people do get a bit of a cognitive jolt from it. It also has a significant effect in terms of oxidation. So nicotine leads to the upregulation of an enzyme I won't bother to name that is beneficial to how the muscles can utilize fat for energy and how the fat cells refrain from just taking more fat in as storage. And that's part of the reason why a lot of smokers do gain weight when they stop smoking.

[Steven Levitt]

Yeah. So you gave me some Nicorette gum, and I've never really smoked, so I've never really experienced nicotine. And I felt great. Maybe it was partly the placebo effect of all your happy stories about it.

[Peter Attia]

Now that I remember, I took out a piece of Nicorette gum, and I started chewing it, and you were like, what's that? And I was like, oh, I chew nicorette gum. And you asked me if I was a smoker. I said, no, no, no. But I love the benefits of nicotine, so I don't really chew it that much anymore just out of sheer laziness. But I still stand by the benefits of nicotine. I think nicotine is a remarkable molecule, and it's unfortunate that, you know, it was typically packaged with an otherwise horrible set of molecules in cigarettes. And I think most people do find a lot of benefit from it.

[Steven Levitt]

One of the things that really bothers me about myself is that I can fall asleep anywhere, anytime, and I do that in academic seminars, and it's incredibly embarrassing. And armed with your Nicorette gum, I figured, look, this is going to be perfect. Every time I go to an academic seminar, I'm going to bring two pieces of Nicorette gum. I'm actually gonna, like, tuck them underneath my lip like chewing tobacco and let it just ease out and keep me going. And despite the fact that outside of the setting of a seminar, Nicorette had an incredible positive effect on me. I would literally fall asleep in two minutes in a seminar, despite the fact that I had the nicotine. So I abandoned that one on my own.

[Peter Attia]

I think you might be confusing a bit of its benefit with that of caffeine, and they have totally different mechanisms. So there's this molecule called adenosine. And the more adenosine you accumulate, the more you fatigue and caffe blocks that, you know, Steve, we should have you take the Epworth Sleep Survey. It's one of the three vetted sleep surveys that really can give us insight into your sleep, and we might have to take a closer look at your sleep habits.

[Steven Levitt]

Oh, God. Well, you know, I have six kids, and I haven't had a good night's sleep in 18 years. And I think you've come to appreciate in recent years, the importance of sleep.

[Peter Attia]

Yeah, that's another example of something that I think prior to 2012, I was very much of the mindset that I'll sleep when I'm dead. And residency certainly reinforced that. So I was probably averaging 28 hours of sleep a week when I was in residency, and it sucked. But I certainly didn't appreciate at the time what it was doing to my health. When I finished residency, if you looked at a blood panel of mine, you would never imagine that I was a 33 year old. I mean, my testosterone was, you know, slightly higher than that of a prepubescent girl. Everything was metabolically broken. And I now realize in retrospect, that was almost assuredly primarily being contributed by the lack of sleep. And so many years later, as I began to actually understand the benefits of sleep, it stands alone as One of what I think of as, you know, one of the four or five pillars of longevity.

[Steven Levitt]

When I was younger and I worked very hard, I just thought, look, if I could sleep less, I would have time to do things I wanted. And so I read the literature and I embarked on the sleep experiment. And at the time, what they said, I don't know if they still say it, was that if you just limit yourself to something like three hours of sleep, you get used to it and your body adjusts to it. And then the key was what they said, if you ever sleep longer than three hours, you ever do one full night of sleep, your body resets completely and you've lost it. So I embarked on a sleep experiment that went on for maybe three months where I did not sleep more than three hours a night and I had all the time in the world. The problem was it was the winter I lived in Boston and I would get so tired that I would go to bed at 8 o' clock at night and then I'd wake up at 11. So my hours from 11 at night until like 5 in the morning in a cold apartment. And in the end it was true that I was like no more tired than I was in general, but I completely lost my will to live. It was really an interesting thing to watch. I just didn't care if I was alive or dead, even though I wasn't even particularly tired. But I just decided death would be welcome. And that's when I stopped my experiment.

[Peter Attia]

Was this in grad school?

[Steven Levitt]

No, it was when I worked in consulting after college and before graduate. But there's a lot of new research coming out among economists of all people, that's starting to flag the importance of sleep. And in particular, I don't know if you've looked at naps at all, but there's some new research that suggests that in terms of afternoon productivity and naps have an incredible impact.

[Peter Attia]

This is actually something that's really interesting. No, the short answer is I'm still trying to make sense of this as well. So let's say you're someone who's only going to get five and a half hours of sleep at night, which for virtually everyone is still suboptimal. Then a 90 minute nap in the middle of the day is restorative and additive to what you get at night, but it needs to be that long nap because that's about the length of time it takes to go through the phases of sleep. If you take a 20 minute afternoon nap, you're not going to get into what's called delta wave sleep, so you're probably just in what are called theta waves. And I actually do find this topic interesting. I don't know that it's a substitute for the nighttime sleep though, so it might be like another totally new way to tap benefit above and beyond the nighttime sleep. Dear McDonald's, your breakfast menu fire tens across the board.

[Steven Levitt]

I could be happy with anything even

[Peter Attia]

though I order the same thing every time. Thanks for not judging me. I'll try something new next time.

[Steven Levitt]

Maybe everybody eats. Get our big breakfast with hotcakes for

[Peter Attia]

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[Peter Attia]

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[Steven Levitt]

So tell me, what are your current feelings towards sugar?

[Peter Attia]

Actually, this is probably one that has changed less than most in the past decade. If anything, I might even be more concerned with sugar, especially in its liquid form. So I think when you say sugar, what you mean is added sugar. So that comes in mostly two forms in the United States, which is sucrose or table sugar, which is that white granular powder or high fructose corn syrup, which is a syrupy liquid approximation of that. So the former is one molecule of something called glucose and one of fructose bound together. The latter is just a liquid mixture of them in a slightly different ratio that favors fructose, which makes it a little sweeter. That's a relevant detail that I'm sure a few people's eyes just rolled back in their head. Why is he telling us this? What's important about that is the Fructose molecule. There's something about that fructose molecule that is really problematic. Now, in very low doses, which is what you would get if you were eating a piece of fruit, there was no problem in eating fructose, but eating the quantities we do now, a mutation that we acquired many years ago starts to work against us. And this mutation actually is what saved our species, because if we didn't have the ability to go to a cold place like Europe and get fat in the fall by eating all of the fructose rich berries, we wouldn't have survived the winters. So again, evolution won. We won. But of course, we live in an environment where natural selection doesn't have the time to make modifications. And so now eating a diet that's high in fructose, again, especially liquid fructose, wreaks all sort of metabolic destruction. And so, to answer your question, Steve, I am still incredibly bearish on sugar. And if people say to me sometimes, hey, man, give me one piece of dietary advice, I'd be like, just start reading labels. If it says it's got sugar in it, eat a different version. If you want bread, eat the bread that has no sugar. If you want pasta sauce, find one that has no sugar. Or better yet, just cut up your own tomatoes and make your own.

[Steven Levitt]

This reminds me of when we had dinner a long time ago and the waitress came up to us and asked if we had any allergies. And you said, well, I'm allergic to sugar. And like, with a great deal of curiosity, she said, what happened to you when you eat sugar? And you looked at her completely deadpan, you. And you say, I die.

[Peter Attia]

What an obnoxious idiot I was. I mean, sometimes I hear stories like that and I just. I'm so embarrassed. The poor, poor waitress.

[Steven Levitt]

So my wife is very upset that I like white bread.

[Peter Attia]

I am, too.

[Steven Levitt]

Is that essentially just sugar?

[Peter Attia]

With white bread, there's another problem, which is, you know, you might get 5 or 6 grams of sugar in it. It's also that it has no fiber left in it as well. So the other thing we always want to be optimizing around is how much fiber can you get? And white bread is generally depleted of anything of value.

[Steven Levitt]

So can you talk about ketosis a little bit and what that means, and tell us about the longest period of time you ever spent in ketosis.

[Peter Attia]

So ketosis is arguably one of the most important, if not the most important, metabolic adaptation that allowed our species to survive. Because our brains are so dependent on glucose. Glucose is such an important molecule for Energy that if we were to go more than about a day and a half without eating, we would begin rapidly destroying our muscle mass in an effort to produce enough glucose to satisfy our brain, which would further impair our ability to forage for food. So we evolved this way to instead break down fat, which even under the leanest times, you still had days, if not months worth of energy from, because fat is so energy dense. And we could turn that fat into a molecule called a ketone. And that ketone was a substitute fuel for glucose and for fat. So the brain could use it as a glucose substitute, and it would offset 50 to 60% of its glucose requirement. But the muscles could use it, the heart could use it, most organs could use it, and it's a wonderful fuel. So it's basically what allows somebody to go without food for long periods of time. Yesterday I just finished a three day fast. So I went three days and just had water. And by the end of that fast, I have very high levels of these things called ketones in my blood and my glucose level is very low. So that's called starvation ketosis. And more recently, and that is to say, you know, in the last hundred years or so, people figured out that you could basically trick your body into doing that by restricting carbohydrates. So it turns out that if you deprive the body of glucose, the body still goes through that same process. And we differentiate that form from the one that we evolved with by calling it nutritional ketosis. So you have this starvation ketosis, nutritional ketosis. I think they often get confounded. Now to your question. I did at one point in my life, circa 2011-2014, spend three years in uninterrupted nutritional ketosis. And these days I spend virtually no time in nutritional ketosis. But I do spend quite a bit of time in starvation ketosis because I fast frequently. So either three days a month or seven days a quarter is typically my fasting routine.

[Steven Levitt]

And so why, what's so good about being in ketosis? What does it do for you metabolically?

[Peter Attia]

Well, I think the benefits of fasting are legion. You know, fasting turns on a process called autophagy. Autophagy is, as its name sort of implies, auto is self phagy is eating. So it's when these cells eat themselves. So it becomes a way for us to recycle our dead or defective cells. So if you have defective cells, you don't want those guys going around rep making cancer cells and things like that. So autophagy is a very important process for preventing cancer. Incredible evidence in how it prevents neurodegeneration and basically all forms of chronic disease. It also impairs senescent cells, or more likely impairs the secreting factors that are made by senescent cells. And senescent cells basically send out these really nasty inflammatory signals to other cells that basically age them. So there are lots of benefits to fasting.

[Steven Levitt]

And how much fasting does a person have to do to start getting those benefits? How often, how long?

[Peter Attia]

No, I mean, look, Steve, that is a million dollar question. That's actually a billion dollar question. Because what you're basically saying is what's the dose? If we're going to take Tylenol, we know the dose right below this, it has no benefit above this, it's toxic. Why don't we know the dose of fasting? And the short answer is it's never been deemed interesting enough to do the studies, which is great news to me because I'm 100% convinced this is a knowable set of answers. But someone just has to do the research. So I think it's a problem that's sub $100 million. And you might say, well, gosh, that's a lot of money. But in the scope of things, that's a trivial sum of money. If we could actually know that this much fasting could extend not just life, but improve quality of life that much.

[Steven Levitt]

So you've devoted much of the last 10 years to understanding longevity better and the things that are under control of people in their behaviors. But roughly how many years are we talking about of extended life, of maybe increased good years of life? Would you guess that somebody who really puts their mind to it can buy through good behavior?

[Peter Attia]

I think without a step function change in our technology and our understanding of science, it probably depends on how bad they are to begin with. So for example, if the argument is that the people who are most disadvantaged genetically will have the greatest benefit from change, the number I talk about with patients is probably five to seven years. There are papers that have talked about and theorized that there's probably a 15 year extension. That is plausible if everything is done right. But what's more important, I think, Steve, is what's the quality of those last 20 years? Because for most people, the last 20 years, especially the last 10 years, are not great, both physically and cognitively. And so if you can say, yeah, you'll live five to seven years longer, call it 10 years longer, but at 85, you're functioning like a fit 65 year old. That's actually a much more important win for almost everyone.

[Steven Levitt]

Yeah, for sure. I look at my father, who's 86 and still runs and still practices medicine full time, and we do trivia contests together, and he's still as good as he ever was. Makes me hopeful that I got some of those genes and I'm gonna have a shot at some of that, too.

[Peter Attia]

Exactly. And look, if you had to choose between someone having your dad's life and he dropped dead tomorrow, let's say he had a heart attack on a run tomorrow, I'd still take that over. The person who lives to be 100 but spent 20 years in a state of decline.

[Steven Levitt]

Ye. Absolutely. The only sad part is my dad said a few days ago, yep, the last person I grew up with and I was friends with, they died. I'm the only one left of anyone I knew when I was young who's still alive and functioning, which, you know, is obviously the only curse that comes with longevity.

[Peter Attia]

But that's such an interesting point. And I remember once I was being interviewed and someone asked me, you know, if you could be granted sort of immortality or something, would you take it? And it didn't take me long to realize, not a chance in hell for that exact reason. I mean, there is, to me, no upside in outliving everyone that matters to you. And so I think death is a very important part of the carbon cycle.

[Steven Levitt]

I'd love to talk with you about COVID because I've been myself a little bit shocked at how ineffective our public policy has been on Covid. And maybe I would also say how ineffective our medical system has been more generally with COVID I mean, if I'm

[Peter Attia]

going to be critical, it's not what we did in the first moment. It's our inability to get smarter as we went along. Why weren't we immediately engaging in a whole bunch of experiments that would very rapidly get us answers to questions that would enable us to decide what to do? For example, why weren't we doing the contact tracing studies in subways and on airplanes and actually figuring out, you know, what is a safe distance to be apart, what type of a mask really matters, what type of a person is going to be safe in what type of an environment to go back to work?

[Steven Levitt]

That's been my reaction exactly, is the answers to every one of the questions you just posed is completely and totally knowable. I mean, not even hard to figure out if you're willing to do randomized experiments. But what was it? What was the failure of either policy or Medicine that led nobody to be generating that knowledge.

[Peter Attia]

So a big part of our clumsy response to this, I think, is that it couldn't be centrally coordinated, and therefore it was just disjointed. Now, it was painful to watch, right? You know, it's easy to be an armchair quarterback, but it's still hard for me to realize why we didn't make a greater effort to ramp up testing quicker. It's complicated because, you know, there are lots of reagents that go into that type of testing, and we don't control the origin of each of those reagents. To me, the more important question, Steve, than the one I spend more time thinking about is, what do you do next time around? If you pay any attention to history? We will have another pandemic that will involve yet another virus. Now, whether it's another SARS coronavirus or an influenza virus or another virus, I don't know. But the probability, Steve, that you or I make it the rest of our lives without another pandemic, I think must be viewed as exceedingly small. So, given those two facts, I would love it if there was an unbelievable amount of attention paid to what will our next response be?

[Steven Levitt]

Yeah, I mean, you've listed a bunch of things that we would want to know the answers to that we don't know the answers to. But my hunch is you'd know better than me is that for things like influenza, we actually don't even know the answer, even though we've had a hundred years to be thinking about that. And that, to me, is where I get shocked at what I'd call the failure of medicine in this dimension to provide us with the answers. That if we had known a lot more about other kinds of infectious diseases, we probably could have been a lot smarter.

[Peter Attia]

Yeah, I mean, most of these viruses are actually benign enough, and there's actually literature that's been done where you can inoculate healthy volunteers. I mean, this is not an unethical thing to do. We're not talking about inoculating someone with hepatitis or hiv. You know, you can really imagine the matrix of studies that needs to be done which says, okay, what does transmission look like inside versus outside, airplane versus subway? This mask versus that mask. Six feet versus two feet. And if you could now paint the boundary conditions of that universe with actual data, the next time a virus comes up, we would at least have boundary conditions to say, oh, this virus looks most like this virus. I'm involved in a coronavirus study now that we're trying to get off the ground that's looking at the long term impact of immunity. So taking a bunch of people who have recovered and asking the question, what does their recovery tell us about their risk of subsequent infection relative to uninfected people.

[Steven Levitt]

This is not a cheap study, I imagine.

[Peter Attia]

No. And just to be clear, I'm just the guy who kind of started it and who raises the money, and I'm the provocateur who helps de risk these things, but I'm not the person that's actually going to do these studies.

[Steven Levitt]

And it sounds like you're doing it all with private money, no government funds at all, is that right?

[Peter Attia]

Correct. It's a very expensive study for one year, but that can be carried by a group of philanthropists who can act quickly and take huge risk and then probably have NIH pick up the tab to really finish it. Because this is a multi year experiment and I think it's the perfect model, which is let the government come in when it's been de risked because there are risks to doing this study. The biggest risk, by the way, is probably mass vaccination. Mass vaccination would interfere with this a lot.

[Steven Levitt]

But when you say risk, you're talking about risk of wasting the money.

[Peter Attia]

Yeah, yeah. But you have to remember, I mean, the NIH is incredibly risk averse. And I don't say that necessarily to be critical, but it's just. You want to talk about incentives, right? They get their money from Congress. They have to basically show every year that there's an ROI on their work. And let's be honest, the House of Representatives is not exactly filled with people who understand science. So I think it puts NIH into a difficult position which is to make very incremental steps in science. But they're not really set up to do big, big thinking.

[Steven Levitt]

Yeah, the parallel in economics. The National Science foundation is the big federal funder of a lot of economists. And when I was applying for my first grant, I went to the senior people around the MIT department where I was, and I said, I have these three new projects I'm going to put into my proposal. I said, no, you got it totally wrong. You have to have one project which is 95% done and turned out well. You have to have a second project which you've actually done, but you pretend that you haven't done it so that they think that you can show them something you haven't done when you're done. And then you have to have a third project which is like 75% done, but nobody knows you even Started doing it, and then you'll just be guaranteed to get NSF funding for that's your life. But it's kind of crazy, right? Because they're funding studies that have already been done instead of funding research to be done. You've given a lot of advice already about nutrition and health, but do you have advice to young people who are trying to find their path in the world, how to figure out where they fit in and how they can lead the best life they can lead?

[Peter Attia]

I don't know. I mean, I probably wish I had been a bit more introspective a bit sooner. I think I probably spent too many years ignoring things that shouldn't have been ignored. Like where did this drive come from? Where did this insecurity come from? I think it's worth understanding that a little bit. And I think a lot of people get there eventually life. But I would just say don't be afraid of that type of exploration. The second thing I would say is really do not consider sunk costs in your career. So I've done a lot of different things and that makes me a master of nothing. But life isn't really about necessarily being the master of something. And so it's okay to be an engineer and then to be a surgeon and then to be a McKinsey guy and then to be a nutrition guy and then to be a this guy and a that guy. So maybe some combination of those two things would be helpful as a person sort of navigates their way.

[Steven Levitt]

Yeah, man. I could not agree with those two things more. In many ways, the advice I give everyone is not to be afraid of change. It's just so hard to quit stuff.

[Peter Attia]

Well, rigidity of thinking is generally a bad thing. And so it might be that it's the rigidity of thought that is really the biggest problem. And the ability to quit or not quit becomes a very high watermark to separate those people out. Which doesn't necessarily undo or undermine the results of that. But it could put a slightly different interpretation on it. Right. Which is what are those people who can't quit also incapable of doing on a day to day basis vis a vis their very rigid view of this is the way to do things versus not. And I'm still, I think, generally a somewhat rigid person, but it's something I at least pay attention to now.

[Steven Levitt]

So you love your children with the depth that is rare and I admire. Do you have specific parenting advice that you would dole out?

[Peter Attia]

No, I think it's the hardest job and I don't think I'm very good at it, Steve. I'm afraid that I haven't done a great job. I'm afraid that I've worked too much. And again, fortunately, Olivia's my oldest, and she's 11. So I know I've got the time to get better and better. But there's a part of me this is not gonna sound great. I'm just not an optimist when it comes to what the world is gonna look like in 50 years. There's days, I guess I am. There's days when I think technology's gonna solve all of our problems. But I get a little bit worried that I don't know how to prepare them for a world that I don't understand. So my guess is there's some measure around helping them become better thinkers. So the other night, here. This is a funny story because it will come across that my daughter lives a tortured life, but she really does enjoy this stuff. So the other night, Olivia's like, daddy, let's watch a movie. And we were like, all right. And there's this. Have you ever seen this thing called Mystery Science Theater 3000?

[Steven Levitt]

Yeah, sure.

[Peter Attia]

Like, totally my favorite thing on the planet, right? And I've got her into it now, so she's like, let's watch MST3K. And then I was going to Netflix to find it, and I came across this Noam Chomsky documentary. And I was like, you know what? Let's watch this thing instead. And she's like, who is this guy? And I said, look, I don't agree with half the things this guy says, but he is categorically one of the smartest dudes ever. And when I was in high school, I became obsessed with him. And the more I learned, frankly, the less I agreed with him. But you should be in the habit of listening to people talk about stuff that you don't agree with. Don't just listen to people say stuff you agree with. And by listening to this guy talk about subjects where I have a different point of view, he's sharpening my point of view and sometimes changing my point of view. And so I want to challenge you to do that. And also, what he's going to talk about in this documentary is really complicated. And I want you to interrupt me every time you have a question. And so we've slogged through this hour documentary on income inequality, basically, and I don't know, would we have been better off watching MST3K? Yeah, some days it's just fun to sit there and laugh. And goof off, and we do that a ton. But I think every once in a while it's good to make them a little uncomfortable and stretch them a little bit. And I hope that's the kind of lesson that I can reinforce, which is you've got to become a good thinker. People I mostly admire is part of the Freakonomics Radio Network and is produced by Freakonomics Radio and Stitcher. Matt Hickey is the producer and Dan

[Steven Levitt]

Dezulla was the engineer of this episode.

[Peter Attia]

All of the music you heard on today's show was composed by Luis Guerra.

[Steven Levitt]

We can be reached at [e-mail] thanks for listening.

[Peter Attia]

The Freakonomics Radio Network the Hidden side of Everything.

[Steven Levitt]

Stitcher

[Peter Attia]

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[Steven Levitt]

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Okay, so that's not like some marketing hyperbole.

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[Peter Attia]

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[Steven Levitt]

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[Steven Levitt]

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