John Miles (4:41)

I am absolutely thrilled Today to welcome Dr. Brennan Spiegel to Passion Struck. Welcome, Brendan. How are you today?

Dr. Brennan Spiegel (4:47)

Doing great, thanks for having me.

John Miles (4:49)

I always love to start these episodes out with a thought provoking question. You are a gastroenterologist who runs Cedars Sinai's virtual medicine program and you hold a chair in the Digital Health Ethics, which is really an unusual combo. What problem have you been trying to solve across those domains? And what's the through line?

Dr. Brennan Spiegel (5:12)

The through line is how do we blend human expertise and wisdom with machines. I like to think of it as BI instead of AI Blended intelligence. So you mentioned I'm the chair of Digital Health Ethics, which is a new title here. And the whole idea is as we enter this world of artificial intelligence, how do we blend the intrinsic humanity of our minds with this new form of pseudo intelligence in the form of AI, ideally to improve human health. And I'm a doctor and I'm interested in healthcare. So that's what my lab spends a lot of time focusing on outside of gravity. And some of these other topics we might talk about today.

John Miles (5:56)

And how do you think this digital health ethics crosses over to things like Max Bazerman or Jayvon Bavel? Some of the people who are more in the behavioral science space behavioral economics have been studying for years.

Dr. Brennan Spiegel (6:11)

Behavioral economics is really about how to optimize decision making, how to be efficient in how we approach complexity and complex problems. I spent a lot of time with my graduate students talking about behavioral economics and the work of Kahneman Tversky, for example. And really, when I take a step back, I think about our psychology and what do we do as humans? We are trying to find patterns in chaos. We are surrounded by entropy, by a world that's trying to pull us apart, both physically, emotionally, and in many other domains. And what we do as humans is we make sense of the world, the physical input in our bodies, which is part of what this new book is about. Emotional inputs. And how do we create a coherent narrative in our mind's eye that allows us to find patterns that allow us to survive and thrive. And behavioral economics is a set of tools to do that efficiently. But psychologically, that's what we're doing, and that's what AI is starting to teach us in terms of how we go about doing that. So it's a really amazing time to be thinking about these problems.

John Miles (7:22)

Sure is. And when I think of AI, one of the things I think we all have to look at is a falsification type of checklist. So it begs the question, when you're chasing big ideas, what's your falsification checklist? What would have to be true for you to abandon a compelling theory?

Dr. Brennan Spiegel (7:41)

Well, I think I approach it like any scientific inquiry. An idea is true and worthwhile if it repeatedly points towards decisions that optimize our utilities. And by utility, I mean from an economic standpoint. We can talk about it in terms of doing the most good for the most people, psychologically, emotionally, financially. We're trying to do the most good for the most people. And some ideas are better at that than others. And we use science to figure this out. We do experiments. So. So it comes down to science and experimentation and having a hypothesis about whether an idea will perform in a certain way or Not. And we do experiments, whether we're experimenting with AI in terms of how it can make decisions or not, or how it could lead us astray. Does it have bias? Bias across many different domains. Now, this is a very theoretical discussion, but we have checklists for things that we look for when we're pursuing research ideas. And this is a sense of the kinds of things we're looking for.

John Miles (8:47)

I wrote a book that came out in February 2024, and I just had a book club in England consume the book. And I happened to be on their last call, and I got a whole bunch of what I would say, critique from peers. So I just wanted to ask you a fun question. What's the best serious critique that you've received in a peer review? And did it change your mind about how you were approaching your work in any way?

Dr. Brennan Spiegel (9:15)

Oh, my goodness. It's a great question. I've published over 300 papers, so I've received thousands and thousands of critiques. And I will say that part of being in academics is being very comfortable with critiques and understanding that's part of the process. And there are brilliant people who are taking time out of their days to think about what you did wrong. I think about an example recently where we've been examining whether artificial intelligence can help provide mental health support. And we published one of the very first papers in one of the Nature journals about how patients react to an AI chatbot and found it extremely beneficial. But in the critiques, they appropriately said, what's going to happen to humans? What's going to happen to human therapists? Are we just replacing them with AI robots? And, of course, I never thought that, but I realized we need to be much more explicit about if this works, how are we going to use it? And be more careful about the language that we use around using AI for mental health, where all sorts of untoward things can happen. So part of being in science is having these guardrails, people who are keeping you in check, and you're trying to constantly respond to them and react to them and improve your work.

John Miles (10:41)

Thank you for sharing that. And that kind of leads us into your new book, Pull. The subtitle is how gravity shapes your body, steadies the mind, and guides our health. So I think the first thing we need to ground ourselves in is what is biogravitational medicine?

Dr. Brennan Spiegel (10:58)

So as you and I are talking right now, we're both sitting down. We are not falling over onto the ground. We're able to stay up, and our bodies are pumping blood up into Our brains and our muscles are firing. Our inner ear is keeping us upright. And that's because gravity was here long before you and I were. Gravity was here before any signs of life. Gravity came first and biology came second. So it stands to reason that every part of your body, every sinew, every cell, every organ, every nerve, evolved to manage this fundamental force of physics. And all biogravitational medicine is. When we look at the human body and mind, by the way, through that lens, all sorts of seeming mysteries snap into view in a way that helps us be more holistic and comprehensive about our care. And that's what this book is all about.

John Miles (12:00)

I think that's a great way to describe it, because I was wondering, and it's what intrigued me about having this discussion, what it was all about. What's do you think is the strongest piece of evidence that kind of explains what the current models don't?

Dr. Brennan Spiegel (12:19)

Well, there's many ways to approach this, but we'll start with probably the most intuitive and then we can work out perhaps to maybe more surprising or less intuitive things. We know from science, from just about every study ever written, that longevity is clearly tied to strength, to physical capacity, to your weight. To live longer, we need to be stronger, we need to be lighter, we need to be better balanced. Our literal relationship to this planet. Literal will determine your longevity. And so this helps us understand why strength is so important. It helps you literally stand up and stay up as long as you can and as well as you can, until inevitably this force eventually pulls us down. And poignantly, in some traditions, we end up. I hate to say this, but we end up in a grave, which is a gravity box. Literally. The word grave shares the same root as gravity. That's where we end. At least maybe physically, spiritually, we might rise. So when we think about it like this, we start to understand why it's so vital, whether you're managing your gut health. And I'm a gastroenterologist, we could talk about that. Your brain health, your lymphatics, your cardiovascular, their inner pumps and tubes. We are gravity fighting machines that unlocks all of our abilities in life, is to fight it.

John Miles (13:54)

Yeah. And let's just say one of the listeners out there is a clinician. My wife happens to be a nurse practitioner.

Dr. Brennan Spiegel (14:02)

Yeah.

John Miles (14:03)

How would you define gravity intolerance to her? And how would she go about suspecting it?

Dr. Brennan Spiegel (14:10)

Gravity intolerance takes many forms. What is low back pain? For starters, if not a form of gravity intolerance, what is swelling in the ankles? That's Gravity intolerance, heart failure, dizziness, vertigo. I've written papers about stomach pain, butterflies in the belly. When you're on a roller coaster, falling, having a gravity challenge, your belly lights up, you get butterflies. Why is that? There's reasons for that we could talk about. These are all symptoms of a broader condition called gravity intolerance. And we don't use those words. Instead, we say, oh, you have irritable bowel syndrome, you have heart failure, you have dizziness. And those words make sense too. But we look at the body by organ system and sometimes we don't take a step back. For example, I have many patients that come to me with irritable bowel syndrome. And then when I shake their hand, I notice that their wrist is clicking. And then when I ask them to bend their pinky back, it goes way back, way more than I can do. Or they can take their thumb and bring it all the way to their forearm, something I can't do. And I come to realize that they have hypermobility. Some of them have Ehlers Danlos syndrome. And what they actually have is gravity intolerance. Their gut is on a suspension system that's also stretchy and it collapses all the way into the basin of their pelvis. And on X rays we see this. And the solution, there isn't more medicines, it's abdominal exercise, it's back exercises, it's improving your posture, the spine, the chassis of the body that hoists everything up. These are just examples. And there's so many more we could talk about.

John Miles (15:47)

Yeah. You mentioned ibs. Have you found any link to colitis?

Dr. Brennan Spiegel (15:51)

Yeah. So colitis, for example, can flare in airplanes, can flare at high altitude. Those are just a few observations. And that's a gravitational effect. When we get in an airplane, the squeeze of gravity on the atmosphere is less. And this changes a number of aspects about our physiology, including even our gut microbiome. The gut microbiome also evolved at sea level. Our serotonin biology changes at high altitude. People with inflammatory bowel disease, like Crohn's disease or ulcerative colitis, may actually have a flare up at the high altitude zones of. In Tibet, for example, there's evidence that IBS is much more common. There's all sorts of literature out there showing this kind of hidden relationship, which is right in our face, that where you are on the planet altitudinally, latitudinally, will affect your physiology.

John Miles (16:48)

Speaking of gravity and our stomachs, is there any correlation that you found between foods that we eat and gravitational Pull.

Dr. Brennan Spiegel (16:57)

Yes, Serotonin is, I've mentioned a few times here, and what's surprising to some people is most all the serotonin in your body is not in your brain. We usually think of it as a mood elevator. Think about that word, by the way. Elevate is high, depress is low. So there's a verticality even in our neuropsychology, but 95% of it comes from your gut, particularly from the gut microbiome that we co evolved with. And I think of serotonin actually as a gravity management substance. Without it, you would be a flaccid sack on the ground right now. Unable to rise, babies can barely get up. They have very little serotonin in their body because they haven't started to populate their gut with a microbiome. We each have a unique microbiome, serotonin production complex. And serotonin is vital for the pumps and tubes in your body to contract and push pressures up so you can stand up the lymphatic flow, cardiovascular, the heart, something called the baroreceptor reflex. So now all of a sudden we're looking at the gut and realizing that it affects the whole body and the diet that we eat, particularly tryptophan rich foods can help boost serotonin production in the gut and balance or rebalance serotonin levels ultimately to help you fight gravity.

John Miles (18:20)

Well, I guess what you're saying is there's a causal link between the microbiome, serotonin posture and motility. So if that's the case, where is it weakest?

Dr. Brennan Spiegel (18:36)

So I guess the weakness could be thought of in different ways. Right. The breakdowns that occur in the gut microbiome can occur through many different mechanisms. One is just literally your posture. So we talked about that. So if you're not strong in your back and absurd, and you just hunch over all day and just think how sedentary we all are these days, sitting down. The gut compresses, even just a little bit. It compresses, but when you sit up, it's like a marionette on strings. You can animate the marionette. The gut is like a functional stack. It suspends itself like a sack of potatoes that we have to carry around our whole life. And some people are better at carrying that sack of potatoes around than others. And so the weaknesses occur if you have a weak back or if you have stretchy ligaments on the inside of your body and then the intestines compress almost like a garden hose if it's not laid out properly and kinked, it gets backed up. You get microbiome overgrowth, bacterial overgrowth, gas formation, serotonin dysregulation, and then you're off into the races. Now you're having depression, you have anxiety, you have body pains all over your body and it's a complete breakdown. So that's a longer answer to your question, but that's how I think about it.

John Miles (19:54)

I hope you're finding inspiration in my conversation with Brennan Spiegel. We'll return shortly after a quick break from our sponsors. Thank you for supporting those who support the show. You're listening to Passion Struck on the Passion Struck Network. Welcome back to my conversation with Brennan Spiegel.

John Miles (20:15)

I think that's a great metaphor. This past weekend, I was doing some power washing around our pool and we have a kink in our hose that this is supposed to be one of those hoses that's anti kink, but one is developed and it drives me nuts because oftentimes it's off all the pressure and I have to walk back 30ft to go move it again. But it's interesting how that's how what you're saying. Our body's doing the same thing.

Dr. Brennan Spiegel (20:42)

It's basic physics. And this explains why if you stand up straight or you use a standing desk all day, you can just almost do an exercise right now. If you punch forward with your shoulders down and your kind of belly all compressed, you can feel the difference in your belly versus if you literally raise up your diaphragm, raise it up, contracting the muscles between your scapula or your shoulders and your back. Just feel the difference in the belly. It's subtle, but there is a pressurization that occurs if you're bent over all day. We're not meant to be bent over. Our ancestors were running around like crazy. They were strong, very little body fat in their belly. That functional stack was upright, like ornaments hanging off a Christmas tree. You want it to dangle in a way that's functional. It's a funny analogy, but that's the idea.

John Miles (21:33)

I'm using a standing desk right now. I always love doing these interviews standing up for whatever reason. I've been doing it for about eight years now, but I like to stand throughout the day because I think it gets the metabolism moving and just gets me out of my chair.

Dr. Brennan Spiegel (21:48)

Well, they say standing is the. Or sitting is the new smoking.

John Miles (21:51)

Yes.

Dr. Brennan Spiegel (21:51)

And not only do I use a standing desk too, but I wear a weighted vest. Not wearing one right now, but I normally wear a 20 pound weighted vest and I put 20 pound ankle weights on both my ankles and I stand on a balance board or sometimes a desk stepper to constantly have this background force on my body to stay upright and strong.

John Miles (22:10)

I'm glad you brought this whole thing up because I wasn't originally going to go here, but I was recently listening to NPR and they had this segment on the hype all around wearing body vests. The conclusion from the specialists that they had on the show was that of all the hacks people are doing, this is one that is definitely probably not going to hurt. You can probably help you a lot, but I think we all feel the difference if we've ever gained weight, how different your body feels when you're carrying a heavier load and especially if you're hiking up a hill. Can you go through some of the benefits of wearing a weighted vest and doing this and why it's something that we should consider doing?

Dr. Brennan Spiegel (22:54)

Saw that same article. Several people sent it to me when it came out. And actually in the book, in this new book poll, I did a self experiment for eight weeks where I monitored a variety of physical functions and wore all this weight for eight weeks to see what would happen. And in the book I tell the details, but I lost four pounds without trying. I was able to do three times as many squats without exercising. My VO2 actually went up in terms of my ability to efficiently use oxygen just by sitting around in a weighted vest and ankle weights. So there's also this trend called rucking where you exercise or run. This comes from the military wearing a weighted backpack or a vest. And it turns out there's something called the gravitostat, which is like a homeostatic mechanism in your body. Your bones are constantly compressed from gravity. If you add a lot of weight all at once, like with a weighted vest, the bones feel it. And there's a theory that the bones send signals, in essence to the brain, saying we have to increase metabolism because we're too heavy. It's like we're on a new planet that's too strong for our bones to manage. So we're going to have to lose weight. And literally that's been shown in both animal studies and in human studies, particularly out of Sweden, demonstrating that weighted vests can lead to weight loss, probably through this gravitostat mechanism.

John Miles (24:23)

Yeah, it's interesting. When I was in the military, I remember doing the 10, 15, 20 mile force walks where you're carrying 50, 60 pounds on your back and your weapon and everything else. And man, you have to build up to it.

Dr. Brennan Spiegel (24:36)

Exactly. Well, you do. And you know better than most of us. When I started wearing that weighted vest, and I'm a marathon runner and I'm in decent shape, but even then I was exhausted. By the end of the day, I even felt some palpitations in my heart. I was exhausted and I realized, boy, I'm gonna have to go slow on this. But after about a week or two, it just becomes a normal feeling. It's no big deal at all to wear all that weight.

John Miles (25:01)

I'm glad we went into that. But I want to touch on something that you talked about a little bit earlier, and that was the tie to emotions. So I want to get into mental gravity. In the book you write that sadness feels heavy for a reason. Vestibular signals anchor selfhood, and when they desync, anxiety and derealization spike. And so my follow up to that is, if emotions feel heavier or lighter, how do we separate cause from metaphor? And can stimulating the vestibular system really shift mood?

Dr. Brennan Spiegel (25:33)

Yes, great question. Lot to unpack there. It does seem initially like this is just metaphor. Think about the language that we use in everyday conversation. I feel up. You get, quote, high, right? On drugs or on life or when there's a lot of serotonin in your brain, you feel high, literally buoyant, right? Ecstatic. And then when we're sad or depressed, we feel low. And it sounds like just metaphor, but think about depression. Depression is almost as if you're living on a planet with too much gravity. You can't get out of bed, you're exhausted, weighted down, physically weighted down. Shoulders are slumped over, looking at your toes, can hardly get through the day, don't have the energy. It's like you're living on a planet that is pulling you down. And it turns out we do have a system that manages gravity. Why wouldn't we? We need to stand up and stay up. It's called graviception. This is another sense that we never talk about, really. It turns out there's a part of the brain, particularly the anterior insula in the brain, that is like a control panel monitoring all of your gravitational signals. And it is interpreting gravity. And that informs your emotions. It informs your thoughts and cognitions and feelings. So it's not just a metaphor. It turns out that some people interpret gravity differently. It's almost like falling into a black hole. Time and space slow down. Time comes to a still a standstill in gravity. That's the felt experience of severe gravity. And so Lachlan Kent is a neuroscientist in Australia who has written extensively about this not just being a metaphor, but actually being based in our neurophysiology. We like to stand up and look up. We look up to the clouds and the sky for inspiration. Church steeples point towards the heavens. We feel down and depressed and on the ground and low when we're sad. And so this is just the beginning. And the inner ear you mentioned, we could talk about that too. But I'll halt there for a second because I threw a lot out there and see if you have any thoughts about that.

John Miles (27:44)

I think it's really an interesting concept and it's one of the main ones that I was going to get to. You beat me to it. But I was wondering. There have been a lot of experts who've come on my show who have talked about the need to do more extensive blood work. Mark Hyman has been the recent one who started a company to do just this. And I agree. When you go to your normal primary care physician, they just do a basic. They're not measuring any of your beyond the core things. They're not really getting into a lot of your. The more important levels that I think we need to be looking at. I use that as a lead in to if there was a lab panel we could include, what would it be for graviception?

Dr. Brennan Spiegel (28:30)

That's really interesting. I would start with non laboratory measurements first so then we could think about laboratory measurements because gravitoception can be measured in lots of different ways. Just to get an assessment of, of your ability to manage gravity. How long can you stand on one foot without falling down? This is a measurement, not a lab test. I know you asked about labs and I'll get there, but this is a predictor of how long you're going to live. Literally as we get older, your ability to stand up to gravity without falling down will predict your survival. So that's a very simple thing. Your grip strength, how strongly do you grip on a dynamometer, for example? And there are metrics for that. How long can you hang from a hanging bar? Just a dead hang. How long can you do that for? That has a lot of predictive validity for your relationship to gravity. Your heart rate variability, that to me is actually a gravity management mechanism. And your vagus nerve is related to that too. These are gravity management systems, as I think about and talk about in the book. You can measure heart rate variability, which is the beat to beat variation in your heart rate on an Apple watch or in all sorts of different devices. So even before we get to lab tests. Right. We can think more broadly about functional tests that give you a sense of where you are in relationship to gravity and then psychological assessments too. We're developing, for example, a mental gravity checklist. And on my website I have some questions you can ask yourself to figure out where things are breaking down. The lab side, it's harder to say. I am all for finding new biomarkers that are validated that can help us predict longevity. It's not an area I have a lot of expertise in, to be honest. Serotonin biology is something we don't do enough of. We do need to have a better handle on serotonin biology and on microbiome biology. We have not really gotten the science where it needs to be yet with understanding the microbiome serotonin complex in each individual. That's my wish list is for scientists to start figuring some of that out. And definitely neurotransmitter levels, for example, norepinephrine, epinephrine, and the balance between these different and the ratios between these different circulating neurohormones, we don't really have a good idea. And I think AI can help us start figuring these things out of what is the right combination of neurotransmitters circulating in your body. But we don't have enough information yet.

John Miles (31:04)

I'm glad you brought up the biomarkers, because to me, the biomarkers really go hand in hand with your epigenetics. Are there predictors from our epigenetics that impact gravisception?

Dr. Brennan Spiegel (31:16)

I don't know that anyone's looked at that. I think it's a really interesting question. If there are certain genetics or epigenetic combinations that strengthen your resilience to gravity. I think you've just identified a huge research field that we need to go into. But I don't have a good answer to that. Great question.

John Miles (31:35)

So one thing I, before we left this topic is if you were a listener tuning into this and you now hear this gravisception, which probably 99% of them never heard before, is there like a perspective prediction that you could give them that they could test something out over the next weeks or month to show them in their own life that this is actually real versus they're hearing this and thinking, man, this is a lot of hot air.

Dr. Brennan Spiegel (32:06)

Yeah, well, hopefully it doesn't sound like hot air because everything we've talked about today is really not pseudoscience. It's based in what we already know about the human body. It's Just rethinking it through this lens of gravity and how do we reevaluate our relationship to it? So in the book, I talk about three different ways to assess your gravity resilience. And they break down first into the physical. I call this gravity fortitude. This is literally like, how strong are you? We talked about a couple measurements, your grip strength, your hanging bar time and so on. And the second is your gravity sensing, which is how your nervous system is processing in gravity. The one legged stand test is a good one. For example, there's also measurements of the inner ear function. So I happen to have an inner ear issue. So I get dizzy.

John Miles (32:56)

That makes two of us.

Dr. Brennan Spiegel (32:57)

I have something called bppv, benign paroxysmal positional vertigo. So I have these tiny little calcium stones that are floating around in my inner ear which can throw off your sense of self, Literally your sense of self. The inner ear, you mentioned this earlier, is like the glue that holds the mind and body together. That's what it does. It is telling you that you are in your body and not in somebody else's body. So if you have an inner ear issue, and there are ways to look at this, for example, looking for nystagmus in the eyes, which is a beating eye, when you move your head around in different directions. And you can check out how to do that in all sorts of online sites, see an ENT doctor, for example. They can do that too. These are measurements. And then mental gravity is the third piece we've been talking about. So there's gravity fortitude, there's gravity sensing and there's mental gravity. And often I'll ask people to do questionnaires, like the NIH has questionnaires for mental health called Promise. And then get your baseline across these things. Figure out where you're weakest and then start a anti gravity procedure. Start working out, doing abdominal or do some ab workouts, do hypopressive exercises where you suck your belly in and hold it and let go. And then suck your belly in like you're bringing your gut all the way up into your chest and let go. Work out your back, do planks, do all this basic stuff. But don't just measure how strong you are. Measure how you're feeling, how long you can hang from a bar, how well you can stand on one leg, what your physical and emotional health is like. Monitor all those things and you'll be absolutely shocked to see how quickly if you change your relationship to gravity, you change your entire mind and body.

John Miles (34:40)

Yeah. Thank you for sharing that, and it's interesting. You said you were a marathoner. I've run a couple in my life as well. When I was younger, I really love to do spin classes, and I actually used to teach them when I was younger. And I remember people would always ask me, what's the key to being really good at it? And I said, it all has to do with. With your core. What a lot of people don't do when they're spinning is I constantly hold my core in, especially as you're going up and down or doing exercises, because a lot of the things that you will do in a spin class is it's actually like doing crunches, but you typically don't even know you're doing it. But it was one of the things that made my course stronger than anything else.

Dr. Brennan Spiegel (35:20)

Between that and doing yoga, that's a great example. The course so fundamental. And in part, we lose track of the fact that I mentioned this before. We have this sack of potatoes in our belly. That's the intestinal system. We all got this heavy sac in there, and we have to cocoon it and keep it upright and strengthen it. And so part of what the core workouts are doing is not only allowing you to articulate your entire body in relation to gravity from the center, but it's also strengthening the wrapping, in essence, around the intestinal system. And it's those connection points between them, the seams of the body, that we rarely ever talk about. In fact, this is why Tom Brady was so amazing and durable as a quarterback is he wasn't the strongest guy. He was the most durable guy. He figured out how to strengthen the seams. We call this tensegrity, tensile integrity, so you can bend without breaking. And so the core is all part of. Of strengthening not just the muscles around the outside, but the connection points in between that create a more durable but also resilient physical body. That's everything that's happening in dynamic exercises, not just in the weight room, where some of the biggest guys in the NFL are out quickly because they're torn to pieces. It's not just about the size of your muscles. It's about the tensegrity of your body.

John Miles (36:40)

Which explains why flexibility is so key. And when I was in service, that's where I got exposed to doing yoga, because I spent a few years with Seal teams, and it was one of the common things that they were doing. One for the breathwork side of it, but two for the flexibility side of it. So in the book, you propose something called the goldilocks zone of human health where you have found gravity stress is most optimal? Is there a study that you've looked at that shows the cleanest dose response between gravity and the impacts that it.

Dr. Brennan Spiegel (37:20)

Has on us that could be thought of in so many different ways. When I think about the gravity Goldilocks zone, what I'm thinking about there, we could talk about some studies is each of us has our own unique makeup, physical, emotional, and our own unique relationship to this planet that we're all walking around on. And sometimes we can handle gravity really well. Some people can't. It's almost like you have an allergy to gravity. Some people call a gravity allergy when they stand up and they get lightheaded and pass out or they have stomach aches at high altitude. So if you look at astronauts, for example, they have no gravity, or at least micro gravity. And they have a lot of issues up there. They get stomach issues, their microbiome changes, their serotonin levels change, their heart rate variability changes, they get kidney stones, they get infections up there because their immune system starts to change. They get headaches, all sorts of blood issues with blood not moving in the body the way we're used to. It's not easy sledding up there, as you can imagine. And so that's an example of the Goldilocks zone, where too little gravity is a problem, but too much gravity for some people is a problem too. It's finding that intermediate stage and changing your relationship to gravity. You know, people sometimes joke around, what am I supposed to do? Leave the planet? No, but you can change your relationship to gravity right here on this planet. So there's all sorts of studies that show different forms of dose response relationships, whether we're looking at the immune system and altitude. We do know that serotonin and immune function in the gut especially change the higher you go in altitude and even in outer space. That's an example of dose response. But, boy, there's so many ways to answer that question. But the general principle is that we have a safe zone where we operate because we evolved on this planet. We were born, as far as we can tell from this planet, we are an emergent property of. Of this planet. So it stands to reason that we're designed for this planet.

John Miles (39:27)

Kevin, you just brought that up. I've got an interesting question for you. Okay, so last night I happened to be a Naval Academy graduate, and I was at our local chapters monthly meeting, and I was talking to a friend of mine, Steve Swift, and one of his classmates, class of 1987 is Suni Williams, who was recently abandoned, stuck in space for an extended period of time. And she's recently been selected to be a distinguished graduate of the Naval Academy, which is why she came up, and she's getting that distinction tomorrow in a ceremony. Actually, where I'm going with this is during that conversation with Steve, who's also a marathon and runner and triathlete. He said, you know what's interesting is years ago, I ran the Boston Marathon, and Sonny ran it, too, but I ran it on Earth, and she ran it up in the International Space Station. And I just wanted to ask you, given what you were just saying, like, how hard would it be for her to run a marathon up in space, given this whole gravity discussion we've been having?

Dr. Brennan Spiegel (40:31)

First of all, thanks for your service. And I worked at the VA for many years and really, really look up to you guys. So thank you for what you've done. In terms of your question, that's interesting, because we do know that in the International Space Station, astronauts need to work out a lot. They need to keep their pumps and tubes moving. The musculoskeletal system gets very weak in outer space. There's been really interesting research showing how osteoporosis, or thinning of the bones accelerates quickly in microgravity orbit. That's because we need gravity to keep pushing on the bones, for the bones to stay durable and strong. And when that's gone, the bones start to hollow out. Fat starts to fill in some of the spaces in the bones. The cardiovascular system, which normally is expecting this pull down to our ankles, is released. And now all the blood is sitting in the chest and in the face. And you know what happens next? The kidneys get all confused and they start peeing a lot. And then what happens next is you get dehydrated. And then after that, you're dehydrated, and your white blood cells are so concentrated that the immune system thinks, you know, that we need to downgrade our immune activity. And then they start getting viral infections. It's like a chain reaction. So to run a marathon under those circumstances is an extraordinary anatomical and physiological feat. It would be curious to see if that's at all possible. I don't know exactly how far they run per day, but certainly not going to be 26 miles. These are questions we have to start asking ourselves as we start thinking about going to Mars and extra planetary travel. How are we going to manage this if our strongest members of our species are having trouble up there? What's going to happen when every day Joe goes up and doesn't have gravity anymore.

John Miles (42:18)

Well, passion struck, listeners. I've tried to get Sunny on the show before, so I guess I'm going to have to try harder to get her to answer that question.

Dr. Brennan Spiegel (42:25)

That'd be a great guest. I love to hear the stories.

John Miles (42:28)

Another thing I wanted to talk to you about, Brennan, is you are one of the pioneers in virtual reality therapeutics. How can stimulating weightlessness or anti gravity environments actually help us treat things that we've been talking about, whether it's depression or pain or health issues or our longevity.

Dr. Brennan Spiegel (42:49)

My laboratory does a few things. One of them is we focus on virtual reality and VR. People think of it for gaming and entertainment, but we actually use it for managing pain, depression, anxiety by creating simulated worlds around an individual that allows them to think differently about their real world. We don't want people getting lost in virtual reality forever. We want them going back to what I like to call rr, real reality with a new perception of the world. And we could debate maybe some other time if we're already in a simulation right now. There's some arguments for that. But simulations in VR can have powerful effects on the mind and body. We've published papers showing how it can change cortisol levels and stress hormones and heart rate variability and immune function and body temperature and white blood cell count. So it's very powerful way to help us change your perception for gravity. We talked earlier about mental gravity, how sometimes people feel like they're falling, literally feel like they're falling physically, metaphysically. The gut feelings in the belly you get with a roller coaster some people get all the time. It's like our body has a G force accelerometer telling you that you're dying. And that's what anxiety sometimes is. It's a metaphorical fall and you feel it in your belly. With virtual reality, we try to reverse that. We try to rise you up, raise you up in VR, floating through the clouds, floating like a bird, changing the physics of your reality, that can actually change the physiology of your body. And when we get that biofeedback component which we now are doing with biosensor, biofeedback people can realize how quickly if they change their perception of gravity and their relationship to it, they change their body and their relationship to this planet. And so that's some of the research that we're working on right now in my laboratory.

John Miles (44:41)

I listened to another episode you were on as I was preparing where you were talking about augmented reality versus virtual reality. I was Having a conversation with Hal Hirschfeld, who you probably know, or you might not know him, I don't know.

Dr. Brennan Spiegel (44:54)

Yeah, yeah.

John Miles (44:54)

He's at ucla. He studies future self and he was talking about exercises that he was doing, using VR to do research on its impact on pursuing your ideal self. If you could virtually see yourself in a virtual reality version of yourself, would it change how you're living in real life? And the answer is yes.

Dr. Brennan Spiegel (45:16)

Yes. Well, first of all, we have to meet because I'm a professor at UCLA too, and we haven't met yet, so that's great. Just to take away from me. Yes. So this idea of virtual embodiment is the idea, we use this a lot, where you can see yourself from afar, zooming up, seeing your body, or you can embed yourself in another body and turn around and see yourself through the eyes of another. This is basically what talk therapy is all about. So when we do talk therapy, you're talking to yourself through another. A really good therapist is taking what you're saying and reflecting it back, taking what you're saying and reflecting it back again. In VR, we literally take you out of your body, have an out of body experience, turn back around, look at yourself. And then we can change the physics of your environment, but also the metaphysics of the environment. And that's what makes the simulation opportunity so powerful, is to change your literal sense of self in this world. And VR can help do that. And I believe it's also helping you re establish your relationship to the physicality of this planet too. The physics of it.

John Miles (46:19)

I love that. And speaking of physics, one of the last things I wanted to talk to you about was roller coasters. Yeah, yeah. I remember growing up as a kid, I grew up in Pennsylvania, and so we would go to Hershey. Hershey park. And when I was growing up, they had the first roller coaster that actually had a loop. And I remember being so scared to go on that thing. And you look at it now compared to what we have, and it's just a complete joke. But in the book you talk about your experience with Colossus, a massive roller coaster at Magic Mountain.

Dr. Brennan Spiegel (46:49)

Yeah.

John Miles (46:51)

How did you learn about gravitypes from Magic Mountain? And could you explain what the gravity types are?

Dr. Brennan Spiegel (46:58)

Absolutely. So I also love to ride roller coasters. I always thought Magic Mountain had the first looping roller coaster revolution, so we'll have to check that. But either way, I love roller coasters. I don't anymore. I've grown out and almost become physically, almost fearful of them. But when I was young we would go down the roller coaster and Colossus used to have a massive drop compared. Now compared to what they have, it's nothing. But I would go on this roller coaster and I always had this ignition in my belly of just gut feelings. And I would bend over and hold my breath. I'd be like, oh my God. My friend who ended up becoming actually a Broadway dancer, really physically impressive guy, would throw his hands up and scream and yell and have the best time. And on the photograph at the end of the ride, you'd see me hunched over, anguished, and him with his hands up and I'm white knuckling. We had two different gravitypes. Our relationship to that fall was physically and mentally different. And you look at somebody like Alex Honnold, who is the rock climber who frees El Capitan. This is a guy who can climb up a cliff without any ropes at all and do it without apparently any obvious fear of falling to his death. And when you look at his brain on a functional MRI scan, which has been done, his amygdala, which is part of these gravity management systems, is quiet. It's the exact opposite of somebody who has irritable bowel syndrome who has gut feelings a lot. Their amygdala fires off quickly. So part of the gravitypes is understanding your mental relationship and not just your physical relationship to gravity. And I realized from that experience that I have a fear of falling. And when I think of it that way, and I might occasionally get gut feelings that I might be anxious about something, I stop and I think, oh, you know what's happening here? I think I'm falling, like metaphorically. I think I'm falling all the way down to the ground. I'm not falling. That's an illusion. I've made that up. I've simulated it in my mind. And what I do is I use virtual reality to practice falling off of a building. And then I combine it with vagus nerve stimulation to help manage my physiologic response. And it actually helps me realize not only is it helping any fear of falling, literal falling, but metaphorical fear of falling. That's partly what I think anxiety is. So that's a little insight into how gravity helps me think about different gravity types and the different types of people and how they relate to the earth.

John Miles (49:33)

So for the listener, this is a good reason to buy Brennan's book Pull. In it you can learn if you're the alert stabilizer, the gravity master, the cautious calibrator, or the adaptive navigator. So we're not going to any more than that, but there's a good chance.

Dr. Brennan Spiegel (49:49)

I almost went there, but it would probably take an hour to unpack all eight of those types. But there are a variety of gravity.

John Miles (49:54)

Types, so I just wanted to do a fun little bit of a rapid fire closer if you're up to it.

Dr. Brennan Spiegel (50:01)

Sure, let's see where it goes. My colleagues are used to seeing me with this straps coming out from under my coat. They're used to seeing me with ankle weights and sometimes they're used to seeing me bouncing up and down on a zoom meeting because I'm stair stepping, which can be a little bit annoying. So I do it with certain colleagues. That's a routine thing that I do now.

John Miles (50:22)

Okay, Virtual reality float tanks or yoga inversion. If listeners could do just one, where should they start?

Dr. Brennan Spiegel (50:30)

I think yoga is a great place to start because it's so accessible. Float tanks are great, there's a lot of interesting evidence behind them. But you have to go find a float tank and sign up and pay for it and whatever. And VR I think is awesome too. But in terms of just everyday accessibility, learning yoga and learning inverted yoga positions can help reorient your physiology. The pumps and tubes in your body in a reversed way. Sometimes tilt tables can be used if you don't have the strength yet to invert for a long period. And some of my patients who have gut issues tell me that when they flip upside down they feel much better. It's like they're giving their suspension systems a rest in the belly. Yoga. Working with a good yoga instructor can be an excellent way to help fight gravity.

John Miles (51:16)

Okay, how about a book outside of medicine that most influenced how you wrote Pull?

Dr. Brennan Spiegel (51:22)

Well, I'm a big fan of Malcolm Gladwell and I spent a lot of time thinking about the book Outliers and the idea of what he really brought to the fore. The 10,000 hour rule, which is when you spend roughly 10,000 hours doing something in a focused and determined way, you become great at it or you have the potential to. And so when I had this insight about gravity, I realized if I'm going to take this seriously, I need to really dig in deep. Not just write a book that is a flight of ideas, but a truly evidence based treatise on this topic as best as I can manage. So I tried to put in 10,000 hours into this book. I don't know how many I actually did, but the back of the book is full of notes that maybe no one will ever read, but I know they're there to try and back up every assertion that I make in this book, and that's in part due to Malcolm Gladwell's way of thinking about what does it mean to become an expert at something.

John Miles (52:28)

I think for me, I have to pass his test as well. I recently read the Revenge of the Tipping Point, which if you ever wondered how Harvard does their admissions, it's a great book to read. Okay, and this is the last one. Finish this sentence. Gravity is not just a force, it's.

Dr. Brennan Spiegel (52:46)

The source of our longevity and lifeblood.

John Miles (52:50)

Love it. Well, I am so honored to have you on Brennan. Where's the best place people can go to learn more about you?

Dr. Brennan Spiegel (52:57)

So I have a website, Brennan SpiegelMD.com and you can also find my info at Cedars Sinai and ucla.

John Miles (53:07)

Well Brandon, such an honor to have you today. Thank you for joining Passion Struck well.

Dr. Brennan Spiegel (53:10)

Thank you so much. Really enjoyed the conversation.

John Miles (53:13)

That's a wrap on Today's conversation with Dr. Brennan Spiegel. What I love about this episode is how it reframes something so ordinary as something so deeply powerful. Gravity isn't just physics, it's a lever for health, resilience, and intentional living. Here are a few reflections to carry with you. First, gravity shows up in your posture, mood and gut, not just in your step. Second, your balance, grip, dead hang, and HRV aren't just fitness metrics. They're early signals of resilience. Third, by working with gravity through daily habits, nervous system training, and mindful movement, you can literally and metaphorically lift yourself. If this conversation helped you see the world a little differently, pay the fee. Share this episode with someone who might be feeling a little dragged down. Second, leave a five star rating on Apple Podcasts or Spotify. It helps new listeners discover Passion Struck. Today was just the beginning of the forces we cannot see. Up next, my conversation with Dr. Bobby Parmar on radical doubt and uncertainty and how questioning what we think we know can pull us toward deeper meaning, better leadership and wiser choices.

John Miles (54:20)

You won't want to miss it.

Dr. Bobby Parmar (54:21)

By embracing doubt and seeing it as a signal for learning, we're able to pay attention to these multiple aspects of a decision. My personal values, the organizational mission, relationships with key stakeholders, financial profitability. And we're able to try to titrate and make sure. Okay, if I'm making a decision that might sacrifice my personal values, I'm doing it intentionally. I'm not doing it as a reaction. I know that in the next decision I better get back to that somehow. Because if I keep going down this path, I'm going to wake up and regret that life that I've lived.

John Miles (54:53)

For more reflections like these, join me each week on our substack theignitedlife.net with behind the scenes insights, book takeaways, workbooks and other tools for living intentionally. And if you want to watch today's conversation, you can do so on our YouTube channels at Passion Struck Clips and John R. Miles until next time, notice the forces pulling at you. Lead with intention and as always, live life. Passion Struck.