Is VO2 Max “Overrated”? (& What To Focus On Instead), Old Man Olympics, Big Toe Health & More With Mark Sisson

Ben Greenfield

My name is Ben Greenfield, and on this episode of The Boundless Life podcast,

Mark Sisson

What is it about longevity that we really are seeking to achieve? It's mobility, right? We want to certainly live longer, but we want to be able to do things as we live longer. We want to be able to walk around the world and travel and play with our grandchildren and all sorts of types of movement. That's my focus. It became more of a decathlete perspective, which is rather than focus on just that one metric, the VO2 Max, all these things start to have real impact.

Ben Greenfield

Welcome to the Boundless Life with me, your host Ben Greenfield. I'm a personal trainer, exercise physiologist and nutritionist, and I'm passionate about helping you discover unparalleled levels of health, fitness, longevity and beyond.

Ben Greenfield

Mark Sisson is my podcast guest. He's been shaking up the world of health and fitness for 20-plus years. He ignited the ancestral health movement in 2006 with his wildly successful blog, which I think is back up based on what you're about to learn in today's show. He's got a book called The Primal Blueprint. He founded Primal Kitchen Food Company, which you may know as the crack-cocaine-esque ketchup and mayonnaise that we all know and love — super healthy and guilt free — and he has a company called Peluva, one of my favorite shoes to wear, toe shoes. All of the show notes for everything we talk about are at bengreenfieldlife.com/sisson2026. Mark's last name is Sisson, bengreenfieldlife.com/sisson2026. Let's go talk to Mark. Mark, it's been a while.

Mark Sisson

Man, it certainly has. Good to catch up.

Ben Greenfield

As a matter of fact, by "a while" I mean the last time I saw you, you kicked my ass with a fat tire ride on Miami Beach.

Mark Sisson

You've got to tell me that was fun, still, right?

Ben Greenfield

Yeah, it was humbling, which I guess is fun. It was character building.

Mark Sisson

Yeah, exactly.

Ben Greenfield

How's Miami treating you?

Mark Sisson

Oh, amazing. I love it here. It's like, you know, it's my happy place. It's like a playground and a kid summer camp and a resort and a spa. What can I tell you? I like warm water. The water's, you know, 20 degrees warmer than what I'm used to in California. So it's all good.

Ben Greenfield

Probably a lot warmer than the pond in my Idaho backyard. I don't know how long ago you jumped back into this, but it seems to me like you've been writing a little bit more — just from the newsletter I've seen, for example, on Beehive.

Mark Sisson

Yeah, so, you know, we had a big issue with Mark's Daily Apple about three years ago. Can't talk too much about it, but Kraft — Kraft bought Primal Kitchen, and with it they got Mark's Daily Apple, and there was a sort of hacking incident that happened that they were unwilling or reluctant to put the site back up for a long time, so it's only recently come back up. Well, while that was down, I started thinking about all of the things that I want to say, all the thoughts that I want to put out into the universe here. And I didn't have a platform, so I started a site on Beehive. It's called Mark's Sisson Untethered. I'm subscribed

Ben Greenfield

to it. I didn't know Mark's Daily Apple was

Mark Sisson

up. Yeah, it's just in the last, I think in the last couple of weeks, it's up again.

Ben Greenfield

Yeah. Well, is it going to be kind of like the database and repository of all the articles that you did over the years, but then your new stuff is now going to be on Beehive? Or are you going to start publishing on Mark's Daily Apple again?

Mark Sisson

No, there's both. So there's Mark's Daily Apple, which is more of the conservative, you know, dietary and fitness and health advice, and then Untethered is more of the spicy — my viewpoint on what's going on in the world and AI and, you know, economics and all that stuff.

Ben Greenfield

Oh yeah, we can get into that before we open the AI can of worms. I think maybe like a week and a half or so ago, you sent out your Old Man Olympics goals, which I thought would be kind of cool to get into, because you pretty much fit in — and I don't know if you appreciate this or not — in the category of like a Laird Hamilton, for me just a dude who's crushing it physically and mentally with age. And so I always pay attention when I see somebody like you publish what your physical goals are. I'd love to dive into what the Old Man Olympics goal metrics are, though.

Mark Sisson

So first of all, this, you know, came about as a result of my analysis of what's going on with the over-hyping of the concept of VO2 Max and, you know, guys like Peter Attia and Huberman and Rhonda Patrick. And, you know, all of the pundits that we've known and loved for a long time seemed to peg VO2 Max as the gold standard for longevity and for risk reduction for all-cause mortality and things like that. And I started really, you know, examining VO2 Max as a concept. I've, obviously, as an endurance athlete, had it be the major metric that I focused on throughout my career. But one of the things I want to point out early on is that I was a fairly good runner and a fairly decent triathlete in the early days, and my VO2 Max was not that impressive. It was like 67 was the highest I ever recorded. And if you look at what's going on in the world of athletics now, marathon runners — the guys who are the best in the world — they have to have at least 80 and usually in the 90s. And Kristian Blummenfelt just recorded 101, which is the highest recorded VO2 Max ever.

Ben Greenfield

Oh my gosh. Wait. Who got 101?

Mark Sisson

Kristian Blummenfelt, the guy who's been winning all the Ironman events now, just ran a 7:21 last in

Ben Greenfield

Do you know what he weighs? Because obviously, part of his

Mark Sisson

He's a big boy. I don't know what he weighs, but you look at him and he doesn't even look skinny. He looks, you know, like a well-muscled guy.

Ben Greenfield

Okay, so he recorded a one

Mark Sisson

on one. I know, so anyway, in the context of my, you know, rather meek and meager 67, I started, you know, in retrospect, looking at what is it about VO2 Max that is so compelling, because, you know, Peter would say that people within the top 2% of their VO2 Max for their age have a 400% lower risk of all-cause mortality than those in the lowest quartile. Which, you know, anybody who's in the top 2% of VO2 Max is almost entirely focused on VO2 Max. You really have to be an endurance beast to get that high and to record those sorts of numbers. And I think in the process, you have to forego a lot of other life skills, you know, which is what happened to me as a marathoner. I didn't ski, I didn't play tennis, I couldn't play basketball or football because I was a runner. I was always sort of focused on developing aerobic capacity and anaerobic threshold, and all of the metrics that we use in the endurance world, to my detriment. And eventually, you know, you become this skinny, wizened old, you know, bag of bones and skin — but you can run a marathon. And so, God bless you. But I looked at, you know, what is it about longevity that we really are seeking to achieve? And it's mobility, right? We want to be able to do things. We want to certainly live longer, but we want to be able to do things as we live longer. We want to be able to walk around the world and travel and play games and play with our grandchildren and, you know, dance and do all sorts of types of movement and save ourselves in the event of a fire or not trip and fall and break a hip. So my focus became more of a decathlete perspective, which is rather than focus on just that one metric, VO2 Max — which they're also using as a proxy — grip strength is another one they use as a proxy.

Ben Greenfield

Yeah, yeah. Well, the three most often cited are VO2 Max, grip strength and walking speed.

Mark Sisson

Yeah. Walking speed, right?

Mark Sisson

So in putting together this list of things, I just thought, well, what would be a good measure of all-round fitness? And so I have things like a 90-second dead hang. I mean, big deal, but that's a real measure of grip strength. How fast can you run the quarter mile? How long can you hold a plank? How many dips can you do? In my case, I wanted to do, you know, 20 dips. I want to do one and a half times my body weight, 10 reps on a hex bar.

Ben Greenfield

By the way, I thought the dips one was interesting. You tend to see push-ups and pull-ups kind of as the body weight exercise metrics. Did you just choose dips for a different reason?

Mark Sisson

I mean, again, that could be a proxy for pull-ups and push-ups too. You can do all of those and throw those all into the list, but in this case, I just was putting it together, Ben. It was literally the list for that day, because the list changes every once in a while, right?

Ben Greenfield

Well, it's a good list, except for those of us who can't train for a hard stand-up paddle for an hour through the ocean or ride a fat tire bike in the sand for an hour straight. But I could probably come up with the Idaho equivalent of that.

Mark Sisson

I'm sure you could. And I invite you to do so. And by the way, I put together a list that I felt I would be the only one my age in the world who could do it. So I would win this particular decathlon. You know, if my son got in, he'd say, okay, you have to play nine holes of golf and score at least less than four over par, something like that, right? It's just a — what it is. Again, it's sort of a fun, not just a game, but it's a fun thought experiment on how do I organize my workouts so that I'm not too confined to just lifting weights? If you look at some of the people in this space, it's just about lifting weights. It's just about heavy weights. Forget the endurance stuff. Forget all of the sprinting. Just lift weights and you'll be good. So in my case, I want to sprint — I'd like to run the 100 in under 15 seconds. Run a quarter in 90 seconds. Doesn't sound like much, but, you know, again, at my age — I'm 72 — all these things start to have real impact. A three-minute plank, you know, and then, for example, one of them is stand on one foot with your arms crossed and your eyes closed, balanced for one minute. Try it sometime. It's not easy. So again, we're combining strength, endurance, mobility, speed, agility. At one point, when I had my slack line, I would have said, you know, be able to traverse 100 feet on a slack line too. But all of this is in service of a well-rounded fitness, not just one that's laser focused on achieving a high VO2 Max. By the way, one thing that people need to understand about VO2 Max is it's genetically predetermined. There's a maximum that you can reach, and you can never train yourself above that genetic maximum. So you can bust your ass for the rest of your life trying to get above — if you're a 45-year-old guy and your max is 55, you'll never get above 55 no matter how much training you do.

Ben Greenfield

I think those who would argue for the benefit of VO2 Max would say, well, it's a general proxy for aerobic fitness, which could translate to lowered risk of cardiovascular disease. And then what I think you might be getting at is that the emphasis on it is so great that the training really shifts towards, you know, whatever — weekly Norwegian four-by-four protocol and multiple high-intensity interval training sessions per week, and getting your long zone two in — and you kind of skew the training towards a pretty big focus on aerobics and not some of the other metrics that you've mentioned, like mobility, grip strength, etc.

Mark Sisson

Yeah, so you sacrifice muscle strength. I mean, the best example I can give you is I was, you know, a multiple sub-2:20 marathoner. I weighed, you know, 140 pounds. I weigh 172 now, so I'm 32 pounds heavier now, same body fat. I lifted weights. I was an aggressive weightlifter in those days, and I could put up 225. I could do a lot, but I couldn't keep any muscle on because the running was so catabolic. The pursuit of this VO2 Max high-end optimization was so catabolic that it cut into the rest of my life, the rest of my functional ability to navigate life, and, you know, climb a ladder and get out of a window in a burning building, and, you know, save your dog, and whatever — the real life skills that people talk about. That was really the revelation. Now, one thing I will note is that most of the things that I do in terms of training — whether it's sprinting one day a week, heavy lifting including a heavy leg day, a bike ride — those all build VO2 Max. So the fact that I'm not focusing on VO2 Max doesn't mean I'm not optimizing.

Ben Greenfield

Yeah, I was going to say, like, the fat tire bike, the stand-up paddle, you're definitely building it. And I think, you know, I mentioned the four-by-four Norwegian protocol. That's one, gosh, I think, like, Dr. Rhonda Patrick has talked about that quite a bit. You know, four minutes maximum sustainable intensity, four-minute recovery, four times through — last I checked that can maintain VO2 Max at like once every two weeks. And I think that's realistic for somebody to be able to throw in. But yeah, I think training every single day to increase VO2 Max, something is going to be sacrificed. And arguably, some of that is going to be related to mobility and functional activities of daily living and strength, which are arguably more important than being at the pointy edge of VO2 Max.

Mark Sisson

Exactly. By the way, the Norwegian four-by-four — I love this because 50 years ago we called that mile repeats.

Ben Greenfield

Yeah.

Mark Sisson

It literally was — we'd run a mile, 4-to-1

Ben Greenfield

work-to-rest ratio. Yeah.

Mark Sisson

It's been around for a long time. So it just all gets relabeled as some fancy new protocol because somebody retested it in a lab and found out, oh yeah, it really does work.

Ben Greenfield

Hot topic — pun intended — in the biohacking and health optimization world is also thermal stress. You know, the focus on sauna and then also cold plunging. Obviously, being submerged in an ice bath for three minutes wasn't on your Old Man Olympics goals. But I'm curious your thoughts on just thermal stress in general, and where that would fit in.

Mark Sisson

You know, I've been cold plunging for 15 years, and Ben, I'm over it. That's the bottom line — cold plunging is distasteful, which is why people do it. It's a hard thing to do, and that's the main reason people do it. I don't buy into the brown fat activation for most people. I don't buy into the anti-inflammatory benefits of it. I mean, maybe to a certain extent, if you're an NBA player and you've got a game tomorrow night, and you sit in the cold plunge — as they have, again, for 50 years — after tonight's game, so you can do it again tomorrow night. But so much has been written also in terms of cold plunging about the negative effects of it — the fact that if it does have any anti-inflammatory benefits, don't do it after a hard workout, or you'll negate some of the biochemical signals that workout produced.

Ben Greenfield

If you do, I mean, volume is important. I think a lot of that is looking at 10-plus-minute cold soaks, long enough and cold enough to reduce muscle temperature considerably. I think taking a quick cold shower after a workout, or doing like a 30-second cold plunge so you're not getting out sweating later on, is reasonable. But like the long cold soaks, yeah, I agree. You see inhibition of mitochondrial biogenesis and satellite cell proliferation, all those other things that happen.

Mark Sisson

At the end of the day, cold plunging has become a dick-measuring contest with people seeing how long they can stay in and then bragging about it. And that's when I got over it. That's when I'm like, you know, it is unpleasant. By the way, I started cold plunging not for any of those benefits. As an ex-triathlete, I hated swimming. I hated getting into an 81-degree public pool until I got warmed up. I just hated that first experience. And so 20 years later, I'm out in my backyard in Malibu, in my unheated pool. I'm like, this is bullshit. I'm going to train myself to get into cold water and not get all freaked out about it. And so every night at 10 o'clock I'd walk out from my house to my pool, which is variously between 48 and 52 degrees in the wintertime. Walk in slowly — not dive in and jump out — walk in slowly, give myself the mantra, you know, it's not good or bad, it's just a sensation. And then stay in there for three minutes. And I had a Jacuzzi right next to it, so I'd get in the jacuzzi, warm up, go to bed and sleep like a baby. So it was more of a mental thing for me. It always was. It was never about the purported brown fat activation, fat-burning benefits. I mean, I've got pretty low body fat as it is. I don't want to lose

Ben Greenfield

more. Yeah, that's funny. Parallel paths. I accidentally got into cold thermogenesis just because you have to train in the water year-round for triathlon. And so Idaho winter, you know, 5am in the morning, standing on the edge of the YMCA pool with a little draft coming in the door. 80 degrees — I mean, up here more like low 70s — and your body hits the water and you're goose-bumping for at least the first 10 minutes of the swim, and you're doing that like five days a week. And then during race season, you know, multiple 40-to-60-minute forays in the cold water, in rivers and lakes and oceans. So yeah, it's kind of forced cold thermo. I think for me, as far as the thermal stress component, a big part of it is I just love to hit the cold right after I finish my sauna session — feels amazing. You know, you get a big rush of endorphins. You feel good. But for me, it's not about shivering and fat loss, it's just about blood flow. I take a siesta in the afternoon. Right before I start my siesta, I turn on the sauna. I get out, I'm in the sauna for 15 minutes, jump in the cold plunge, back to work. And to me, it's an incredible way to start the afternoon.

Mark Sisson

I don't disagree. But again, I think that's an activation of the central nervous system, and has less to do with the thermic effect of the heat and the brown fat activation of the cold and, you know, the heat shock proteins and whatever. It's just more like it feels good — which, look, I would not deny you that at all. That's one of the reasons I did this every night in Malibu before I went to bed — cold plunge, finish with a Jacuzzi, and sleep like a baby. So I'm not denying that it has that benefit. But in terms of the Old Man Olympics thing, the ability to withstand four minutes in a 48-degree cold plunge doesn't intrigue me anymore.

Ben Greenfield

Yeah, nearly everybody that you mentioned early on — not that this is an under-the-bus podcast — Peter, Attia, Rhonda and many others have also, in the past few years, really, I think, increased the sales of non-alcoholic products — NA beer, NA mocktails, NA wine, NA tequila — because of the stance that any alcohol, period, is toxic, poisonous and bad. I think you have a different take on alcohol, and I'd be curious to hear your rant on it.

Mark Sisson

Interestingly, I could give you some science that says the body produces ethanol, and ethanol burns within the human body naturally, providing seven calories per gram. We don't produce a lot of it, but we can produce up to 30 to 35 grams a day of ethanol on our own.

Ben Greenfield

By the way, is that like a Krebs Cycle byproduct?

Mark Sisson

Sure, sure. And it's not a massive one, it's not a major one, but it is definitely something that the human metabolism, the human liver, is equipped to handle quite easily. Where it becomes problematic is quick overdoses. In terms of our ability to withstand small doses of alcohol, we certainly have that ability. It's been part of the human experience ever since we figured out how to ferment berries and meat and corn and honey and things like that. So now, what is the utility of it? Well, there's no real utility of alcohol. It's not like we need it for fuel. There's no requirement for it, but the fact that we do make it in our body and we can combust it — I mean, one of the examples I use is that five grams of glucose in the bloodstream is considered normal, and if you have seven grams of glucose in the bloodstream, you are diabetic. Some overage of glucose is very problematic over the long haul as well. So if we're just kind of arguing the different toxins, any of these things come down to it's not so much the nature of the substance as the dose. All right, back to alcohol. So, you know, I enjoy a glass of wine pretty much every night. And I think there are types of alcohol that are probably really problematic for a lot of people, especially the ones that have the sugars in them, and lots of additives and things like that. I stay away from those myself. Certainly, if you're someone who has an organic issue with alcohol and is lacking some of the critical enzymes in order to metabolize it, stay away. By all means, stay away. I'm not an advocate for everyone drinking alcohol, but for those who come to me and say, look, I enjoy a glass of wine once in a while, but now all the pundits are saying any amount of alcohol is bad — I disagree. I don't think any amount of alcohol is bad. I mean, I have a glass of wine at the end of the day to take the edge off. I would say the amount of cortisol that I might secrete as a result of having had a bad or stressful day, or worrying about or ruminating about something, is maybe mitigated by that glass of wine.

Ben Greenfield

Yeah, I think one of the interesting points you made in a recent newsletter about alcohol was basically, yeah, it disrupts sleep with hefty doses right before you get into bed, but having a glass of, like, I don't know, organic, biodynamic red wine with a 6pm dinner is not going to thrash your 10pm bedtime.

Mark Sisson

Not at all. And, you know, I drink — as you know, I've been a big fan of Dry Farm Wines for a long time. These are wines that are sourced for their relatively lower alcohol content to begin with, for their lack of additives. There are no additives. These are biodynamic wines, grown without irrigation, so the grapes used in many cases are not, as you know, sugary. Whoever grows these grapes has to produce the wine that year from that vintage, from that crop, based on the natural rainfall. A lot of these wines are not overly macerated. You know, in the US, we get a lot of these, particularly California cabs that are just so deep, red, dark, you know, whatever, because the red skins are ground up and ground up and ground — that's where all the tannins and the histamines reside. And so you put those in the wine, now you've got tannins and histamines and sulfites and added sulfites and sugar and extra alcohol. Now you have something that's probably less desirable — from the ability to have a glass or two and have, like, zero effect from having had it, other than, you know, a mild wine euphoria that lasts until you go to sleep.

Ben Greenfield

Yeah, I think the major issue with alcohol, just from a kind of esoteric social standpoint, is there are so many people that just associate it with partying, irresponsible activities, drowning your sorrows, escapism. It's pretty rare that I talk to people who are literally just okay with having a glass of wine with dinner and don't associate that with alcohol abuse. I mean, you know, I've been probably averaging three to five drinks a week for almost 17 years. I can't tell you the last time I got drunk or the last time I had more than like a glass of wine and a cocktail. You can actually drink responsibly and moderately. I just think so many people associate it with irresponsibility or lack of temperance. It doesn't have to be that way.

Mark Sisson

I don't disagree at all. And so I just speak to the people who got kind of freaked out by, again, the online health pundits who suggest that any amount of alcohol is horrible for you. I'm not buying that. And to your point, I mean, I've been drinking wine my whole life, and I can't say I've been drunk in the last 20 years.

Ben Greenfield

If anything, I run into people who will do like the 75 Hard or some amount of time completely abstaining. And one of the first things that happens once they decide they're going to allow themselves to have alcohol is they go out on a bender, you know, just get drunk and, you know, burn through a couple of 12-packs or a bottle of wine. It's like, well, by being consistent and moderate, you actually, you know, kind of paradoxically decrease the chances that you're going to fall into abuse, because you never get to that point where you're like, gosh, it's just been so long.

Mark Sisson

You know, as I say, maybe I have a particular way of looking at everything in life, which is I use the minimum effective dose. What's the minimum effective dose of food I need to get through the day — not what's the most I can eat? What's the minimum effective dose of protein? I don't want to get 200 grams a day. Maybe my minimum effective dose is 110 or 120. What's the minimum effective dose of exercise? Like, I'm not an exercise fiend. I do as little as possible to stay as fit as I can. You've heard me say this in the past — it's better to look fit than to be fit. Now, the irony is, if you do what it takes to look fit, you're probably pretty fit. And so in the case of wine, what's the minimum effective dose of wine? There's a point at which I hit that, and I'm like, no, I don't want — I might have a half a glass of wine left and go, nope, I don't need to finish it. I've had the wine I need for tonight, and that's it.

Ben Greenfield

I think, also, by the way, for those of you who haven't read some of Mark's deeper thoughts, along with some really good science-backed citations on alcohol and its true effects, I'll link to some of his articles in the show notes. So, you know, we talked a little bit about cold plunging, VO2 Max — you know, it's no secret that biohacking is kind of the hot topic right now. Is there anything else in the whole biohacking world that you think is overrated, a waste of people's time, or a complete distraction right now?

Mark Sisson

I've got to tell you, I'm emerging, I guess, as the anti-biohacking guy. I'm just not buying almost any of this stuff — whether it's the methylene blue, whether it's the compression sleeves, whether it's the, you know, getting 48 years of Zen in 15 minutes with a headband on. We can go through the whole litany. And I go to some of these shows, and I see some of the protocols and some of the equipment, and I just have to roll my eyes and go, look, if you guys haven't covered the basics — get your sleep dialed in. And by that I mean 67 degrees, dark room, some ambient white noise, and sleep eight hours, plus or minus, a night. If you haven't figured that out, if you haven't figured your diet out, gotten your protein dialed in, gotten your eating schedule strategized so you develop metabolic flexibility, if you don't have your movement patterns, if you're not walking every single day — don't start talking to me about methylene blue, or doing, as Brian Johnson recently did, your culturally appropriated ritual inebriation ceremonies.

Ben Greenfield

I mean, Mark, I know a guy, and he's working hard, you know, 14-hour days, sleeping very little, eating when he gets a chance, usually very quickly. And he told me, look, I have been struggling with low HRV, and I've heard the intranasal Semax and Selank peptides and a vagal nerve stimulator, and this little device that you wear that kind of coordinates you into resonance breathing would be really good for me. And, you know, my reply was like, well, yeah, maybe, but there's a lot of low-hanging fruit going on right now, and you can't, like, you know, Semax your way out of sleeping six hours a night and then just grinding all day.

Mark Sisson

And I think, you know, I grew up in an era — and you maybe even more so — when grinding was the only way to succeed, right? And so everybody bragged about working 70, 80, 90-hour weeks and foregoing their family life in pursuit of their career. And like, what kind of life is that? If your health is going to suffer as a result of that, that was you making a choice. It's not like there's anything you can magically do to fix that. I think the thing that bothers me most about biohacking is this pursuit of the magic potion, the magic injection, the magic pill, the magic protocol that obviates the need to do the hard work. And you and I know that life is about doing the hard things and reaping the benefits. And at the end of the day, we're getting into a realm that scares the hell out of me — maybe it's a realm of promised abundance.

Ben Greenfield

Yeah, it's interesting, you know. And maybe this is too broad of a stereotype, but I don't run into a lot of former competitive athletes who tend to be prone to overdoing the biohacking. It's usually the tech pros, the people who never really got a chance to push themselves physically in high school, in college sports and club sports, whatever. There does seem to be a mentality of, you know, the type of person who never actually learned what blood, sweat and tears in the gym actually felt like. And again, like we just got done talking about, the avoidance of overtraining being a good thing and the minimal effective dose of exercise. But there tends to be almost like a historical pattern of people who haven't really learned how to do the hard work trying to get dropped off by a helicopter on top of Mount Everest first.

Mark Sisson

There is some of that too, right? That's probably my biggest complaint about this biohacking movement — and you're right, a lot of tech bros. I think the world of tech is full of people who are looking for problems that don't really exist, and then they create the problem, and then they find the solution for it. Like, my favorite example would be Soylent. The tech guys who assumed that everybody must be programmers and everybody must hate to eat, because you have to stop coding when you eat. So you order pizza and have Coca-Cola at your desk, and you keep coding all night, and you sleep on your desk in little cat naps, and then you have more cold pizza, and then you code. And somebody said, people hate to eat, there's just no time. Let's create the be-all, end-all supplement. And they called it Soylent, and it was the worst. And they raised, by the way, something like $150 million to start this company with the assumption that people just wanted to add water to a powder, slam it down and get back to work. People love to eat, man. So this is the tech community making an assumption about what's good for people based on their own experience — creating these problems.

Ben Greenfield

Right now, I think perhaps the 2026 equivalent of that is potentially the use of GLP agonists, or triple agonists, or quadruple agonists, or whatever — which do have a time and a place, I think, for diabetes and obesity — as a way to simply quell the hunger response entirely so that you can continue to hammer. And there's a certain kind of flavor of almost anorexia-enabling that this has created, where people are like, well, you know, I need to push through the day. I don't want to think about eating. Therefore, I'm going to inject this — not necessarily for metabolic management, but just as yet another productivity hack.

Mark Sisson

Exactly, a productivity hack. I mean, when lawyers were taking Ritalin to argue cases against athletes who'd been caught doping — how do you like that one?

Ben Greenfield

Yeah, no, that's the classic. I know people who are on Provigil by day, Valium by night, seven days a week. So you mentioned AI earlier. I don't know what your stance is on that right now. I mean, you obviously write, you produce, you're a content creator, and then you also typically have pretty informed takes on just social trends in general. So I would love to hear your thoughts on AI.

Mark Sisson

It's pretty negative, my thoughts on AI. It's pretty scary. I mean, I think right now, AI is a fairly useful research tool. But currently, all it is is a word-predicting device — or now it's a content-predicting device — that spits out, based on a prompt, a randomized answer based on all of human input into the internet over the past, you know, 50 years. And as such, it's still based on human input, much of which is non-factual, much of which is non-scientific, much of which is opinion, biased, hate. And it's really difficult to call this down and get what I would say is a real source of truth. And so my own experience has been, in the early days, asking it about myself — stuff that I knew about myself — and having it lie, and then having it lie again, and I'm like, no, you're wrong, and it would defend itself, whatever. So it's gotten better and better, but I think the mistakes and the hallucinations are not going to improve much. It's still based on human experience, which is limited. And at the end of the day, I feel like it's going to be a fairly good research tool. I feel like it will probably eliminate the legal profession, because law is just memorization and being able to pull up factual case law and then apply it to

Ben Greenfield

I mean, the legal profession, programming, writing and copywriting, a lot of social positions, a lot of customer service positions. I mean, I think I heard — this was a Microsoft Research report — that the job least likely right now to be replaced by AI is phlebotomy. Literally, people still don't trust a robot to take their blood.

Mark Sisson

I love it. And no, that's a great point. Yeah. So a lot of these jobs — there's not like in law, even in medicine, in accounting, there's no single right answer. There are opinions. So CPAs don't have the answer. When you submit your stuff for taxes, you could submit all of your receipts to 10 different CPAs and get 10 different amounts that you owe the IRS. So even some of these professions don't have a right or wrong answer. And so to have AI come in and maybe do a slightly better job with a more legitimized opinion — that's probably a good thing. I think, you know, they talk about radiologists being made obsolete, because you can feed enough imagery into an AI and have it make a probably better diagnosis than a single individual could. Those are all existing jobs that are going to be rendered a little bit more efficient by AI. And I think that's what it does. I think when I see, like, my son just set up, you know, a Mac Mini with six agents, and he's reorganizing — he owns a warehouse, a fulfillment center — and he's reorganizing how the pallets are arranged and how the picking and packing happens. All of that is in service of maybe extracting another 5% efficiency from a relatively already efficient system. He's not inventing anything new. All he's doing is extracting a little bit more margin. So at some point, all the margin that's available will be extracted, and then there'll be nothing else to do. I see people talking about — a lot of the Instagram people talking about — well, all you need is your Mac Mini, your quad core, your, you know, whatever other AIs you want to put in there, create all these agents, and everybody can start a business, and everybody can be a millionaire within a few days. Well, what product are you going to sell, and who are you going to sell it to?

Ben Greenfield

I think it was Elon Musk who basically said something to that extent — that at some point, at the end of the day, there actually has to be someone making products that improve people's lives versus just creating digital products that train people how to make money making digital products.

Mark Sisson

That's exactly what it's become. It's become people selling programs to coach other people on how to make digital programs to sell other people programs. It's bizarre to me. So I don't think there's going to be much in the way of innovation for the foreseeable future. It's just going to be this margin extraction. Good example — trading on the stock exchange. There's no wealth being generated other than people extracting money from other people who already own stocks. So it's almost a zero-sum game on the stock exchange when AI is involved in figuring out how to make a trade and how to extract a tenth of a penny more per stock because a trade happens quicker, or even the sort of quant-type predictions about what's going to happen to this stock have nothing to do with the value of the company over time — as much as it has to do with who's the idiot who's going to buy this from me in a week at a 5% premium? So all of this is just people taking money from other people. It's not creating wealth. It's not producing anything. It's not adding to GDP, and that's what's scary about it. It's almost like it's become this, you know, selfish opportunity to extract rent from other people. Talk about everybody being a rent seeker now. It's crazy, unless you invent something new. Unless you come up with something new, it's just going to be extracting margin from existing businesses.

Ben Greenfield

Yeah, invent something new, come up with something new, or create analog products that people already use, like my sons — I tell them, good choice, good decision. They're in the card game, board game industry, right? They're literally creating real, analog products that require actual, real humans sitting around the dinner table to utilize their product, and it has to be a novel, unique game, not a carbon copy of Monopoly or Scrabble or whatever. So that's an example of creating something that actually has utility. And then there's others, like, I just set up a Claude — what's it called — a Cowork project that has access to my Slack, my Asana, my email and my Google Calendar. And at 5:45am it sends me a brief of my day — you know, what to expect, when my meetings are, any important emails in my inbox. And then at 8:45pm it sends me an end-of-day summary for me to review before I go to bed and prepare for the next day. And that, to me, is valuable, and something that saves me probably like 10 to 15 minutes in the morning and another 10 to 15 minutes in the evening — so a few hours a week of just reviewing my calendar, planning out the day and reviewing the end of the day.

Mark Sisson

Okay, so it's improving margin in your day. That's great, but it's not making your day. It's not doing everything for you yet. And the danger is when it starts to do that — when we have robotics and our lives become meaningless because we have nothing to do. There's nothing to tinker with. There's no reason to go work in the workshop, because I can have my robot build that for me. The dream that everybody has about this infinite wealth and this massive abundance is probably the scariest thing of all to me, because first of all, you talk about abundance like it's a good thing. Abundance is not always necessary. There's a point at which abundance becomes its own weight.

Ben Greenfield

Obesity and diabetes is abundance.

Mark Sisson

Great example — over-abundance. Yeah. So you know, when we talk about abundance, we have to be careful that we're not losing our humanity, because now all of a sudden — and by the way, the big question I have, Ben, is why do you wake up in the morning when everything is done for you and you don't have to memorize anything? Kids aren't going to have to remember anything. I just envision this world where, because everything is done for you, you don't have to do the hard work, you don't have to put the time in to learn a language, or to learn how to play the piano, or to learn some dance steps. It's all kind of done for you. What is there left to do? And then this is the same world where Dave Asprey says he wants to live to 180. I'm like, dude, why? What's going to be exciting about any day?

Ben Greenfield

Yeah, I think you have to be wired up a certain way — inherently self-driven and possibly autodidactic to a certain extent — to where, let's say there is an age of abundance. You have a robot mowing your lawn and making breakfast and doing all your work for you. Well, there is the type of person who would still wake up and want to craft a beautiful piece of music on the piano or the guitar, or who would want to get a rifle or bow and go hunting in the forest and learn to cook wild game, or who will do something that still scratches that creative, productive urge. And you know, you mentioned the movie — what's the movie where everybody's lazy in the future?

Mark Sisson

Idiocracy?

Ben Greenfield

Yeah, Idiocracy. And then, you know, I think 95% of people fit into the Idiocracy bucket, but I like to think that some people will still have that inherent drive to be productive and creative in different ways. But I think that needs a certain amount of nature and a certain amount of nurture. I like to think that guys like you and me would probably fall into the category of still waking up in the morning and wanting to just make things.

Mark Sisson

Well, this is the thing — I'm a fairly wealthy individual, and I can pretty much do whatever I want. And I get up in the morning and have the same cup of coffee that I had when I was, you know, dirt poor. I do the same workout I did when I was dirt poor. I do the same one-hour walk every night that I can do anywhere in the world with any amount of income. I still love my kids and my grandchildren the same amount no matter how much money I have. I still appreciate a good hike in the mountains, regardless of what the wealth is. So at some point you get to where you realize all we have is the things that make us human, and the layering on of more and more abundance to somehow make it so we don't have to work out that much because we can take a pill — I mean, for me, the first thing happened when I realized I don't have to change the oil in my car. I don't have to replace the muffler myself. I was in my 20s when I realized that. But, you know, it just gets worse and worse over time. Now I just feel like so much of what makes life enjoyable has nothing to do with abundance or wealth, provided you have the right mindset.

Ben Greenfield

Yeah, I was at a different conversation a couple nights ago, and someone was talking about the world of exercise mimetics, and they brought up peptides like something called SLU-PP-332 or something like that, that basically causes mitochondrial biogenesis and skeletal muscle fiber growth or satellite cell proliferation with a pill. And my wife was sitting next to me. She's like, that sounds horrible. I love to exercise. I'm like, me too. I'm not going to pop the pill.

Mark Sisson

The reason you love to exercise is because there's something in the human brain that wants you to do the hard stuff, and that's why every day I want to do something hard — and whether it's a workout, it's usually a workout, but sometimes it's just grinding it out on a paper or something like that, writing an article. There's something about doing the hard stuff every day that makes the rest of the day that much more valuable. And I think that's human nature. It's our modern-day survival instinct, which is basically, I made it through the day, I can sit around the campfire and enjoy — be vigilant for the night, for the night prowlers — but sit around the campfire and enjoy the fruits of our hard work during the day. And I think people tend to lose that. And you're right, exercise is one of those things that it just doesn't even feel that good when you're doing it most of the time, but it really feels good when you stop, and you really feel good about yourself. And there's some biochemical — some endorphin, dopamine, serotonin convergence there that makes you feel like, oh my god, that was an amazing day because of the hard work.

Ben Greenfield

Yeah. What is it, Monday today? So Saturday, I released a podcast with Dr. Matt Dawson where we talked about the morphological and metabolic changes — or differences — between weight loss achieved using a GLP-like drug versus weight loss achieved through diet and exercise. And as you would expect, there is just a slew of multi-organ system benefits that come from the approach that go beyond the drug, like actually doing the hard thing. It's all about how that changes your body, staves off future weight gain, etc.

Mark Sisson

I mean, that's the thing that scares me about this slew that you just talked about. What else is going on? What are the downstream effects? Well, let's go back to GLP-1s. Let's go back to tirzepatide, or some of these, that have apparently, as one of their side effects or other effects, the loss of appetite for sex and connection.

Ben Greenfield

Yeah, yeah, basically almost like a dopamine-blunting thing that goes beyond food.

Mark Sisson

Yes. So the fact that it works for food, okay, great, but now — you know, the main reason you want to lose weight is to get laid, but now you're not interested in

Mark Sisson

or, you know, and it works for alcoholics, who are drug addicts apparently, who don't now have the craving for that dopamine receptor or that cannabinoid receptor. But again, these are sort of multi-effect drugs that are only being used for the one specific effect, or symptom, that they're

Ben Greenfield

and if they could be used like training wheels for self-control and willpower, then why do you see rapid weight gain upon stopping the pharmaceutical, if that happens?

Mark Sisson

You know, they're basically short-term crutches that don't fix the problem.

Ben Greenfield

The thing that I think I would be remiss not to talk with you about is I was golfing — you know, my every-10-year golf excursion — last week, and I was wearing the new kicks that you sent me, the Peluva golf shoes. I got a few compliments. I got the Peluva court shoes now for pickleball and tennis. So what's the latest with Peluva?

Mark Sisson

Oh my God. Just having so much fun. I mean, I get testimonials every day that are basically tear-jerking — about how we're changing lives, about people who had real foot issues and couldn't walk without discomfort, or couldn't work out in the gym without discomfort, now able to do so comfortably, fixing problems over time because they're reacquiring a good, strong, balanced gait, rewiring their kinetic chain that had been rendered imperfect by the shoes they were wearing before. We have a lot of people on the trails. We have a trail shoe called the ATR that we just introduced. It's sort of the Ferrari of trail shoes now. The notion that you could somehow go off-road, go on trails with boulders and jagged rocks and stuff like that, and wear a stiff, thick, high hiking boot and not tweak your knee just boggles my mind. When you're hiking, you want to feel the ground. You want to feel every rock you step on. You want your foot to land in a different position every time you put it down, not be forced to land in the same position and then slide off an angled stone — or a wet angled stone — because it was forced into a neutral position by the boot. So reinforcing what the foot wants to do. The foot wants to be able to feel the ground, and by feeling what's underneath, by the time you weight that front foot, the brain knows exactly how to organize your kinetic chain — how to roll that ankle a little bit off that stone, or how to scrunch the arch around that stone, or how to allow those toes to articulate between the sticks or around the stones or over the divot, or how deeply to bend the knee because you stepped off of a large stone. All these things get negated by stiff, regular hiking boots. And by the way, they get negated by thick, cushioned running shoes, etc. So Peluva was based on this idea that we want our feet to be strong and resilient and mobile. We want to reacquire this perfect gait that we were born with, that got screwed up by the so-called high-tech shoes we're wearing. So we make a shoe for all occasions. You have the court shoe — the pickleball and paddle shoe. We've got one of our top long-drive guys in the world wearing the golf shoe because he connects with the ground better on his tournaments. We've got the hiking shoe. We've got workout shoes. We have a winter boot we just introduced.

Ben Greenfield

Good to know. I was going to ask you when the sub-zero or whatever is going to come out. I was — as a matter of fact, I think I texted you a couple of years ago. We were both somewhere international, commenting to each other about how many looks and comments we get when we're wearing our Peluvas overseas. But I was in Germany two months ago and it was cold. I was walking every day in Munich wearing my Peluvas, but my toes definitely get colder. So fill me in on the winter boot.

Mark Sisson

So we have a winter boot. It's got a shearling lining, it's leather, it's just an amazing boot. It comes up above the ankles. I should have brought one out. I don't know how many people are watching this versus listening.

Mark Sisson

It's a really good-looking boot. And so we have one that looks like an LL Bean version — remember the two-tone?

Ben Greenfield

Is it insulated? Well, I've got one of the boots. I like the brown, kind of Swedish-looking boot that goes higher than the ankle, but it's not insulated.

Mark Sisson

No, no, that's the desert boot that's been around since day one. That's a great going-out-to-dinner boot. I wear that a lot with jeans. That's not what we're talking about. We have a legit winter boot. Now, when I say legit — if it's below 30, because of the toes, you're still going to have a little bit of an issue. But you know, you wear socks with it, and between the socks and the boot and the shearling lining inside, you'll be very comfortable.

Ben Greenfield

Right. I could probably do like September elk hunting in it.

Mark Sisson

Yes, 100%.

Ben Greenfield

Yeah, yeah, and stay whisper quiet. That's the advantage. So one thing on your Old Man Olympics — back to that — is the one minute standing on one foot with arms crossed and eyes closed. Fill people in on this idea of just big toe activation, balance, and overall longevity when it comes to foot health, because, to me, that's one of the biggest advantages.

Mark Sisson

Well, when we talk about longevity, the lowest-hanging fruit — which nobody talks about — is foot health. If you think about it, after the age of 65, one out of every three people falls at some point and breaks a hip, and then 25% of those die within a year. Another 30 to 40% are rendered pretty much immobile as a result of that fall, all of which happens as a result of a cascade of bad events that start with the feet. If your feet are strong — look, as a kid, you trip every day. You're a gangly kid. You trip over everything. Sometimes you fall, but most of the time you don't. You catch yourself, right? If you trip, your feet are strong enough, and your quads are strong enough, and everything's organized so that you reach out with the forward step and catch it. You don't fall. This goes away over time as you lose mobility and strength and resilience in your feet. This happens as a result of a lifetime of compressing the big toe against the other toes. The most egregious effect of modern footwear is this squeezing of the big toe against the rest of the toes at the metatarsal head, which in many cases causes bunions. But in all cases,

Ben Greenfield

while a lot of people have bunions, by the way, like,

Mark Sisson

yes, a lot. And bunions, by the way, are not genetic. You don't have bunions because your mother had them or your father had them. You have bunions because you wore bad shoes. Indigenous people don't have bunions. That's just a bizarre adaptation to crappy footwear. The big toe is the most important joint in the foot. It is essential for locomotion. It wants to splay outwardly, and it wants to be the last point of contact when you push off. So if you're barefoot and you have strong feet, you plant with a heel, you roll off the big toe — plant with a heel, roll off the big toe. There's some supination and some pronation going on in there. The foot is supposed to do both as part of this windlass mechanism that a strong arch provides. But the big toe is the most critical part of the foot, and the fact that we squeeze it up against all the other toes and render it effectively useless and obsolete over a lifetime — it's just criminal. So Peluva was based on this idea that we want the big toe to be the hero, to be the part of the foot that regains its strength. You want it to abduct away from the foot. You want the toes to splay outwardly. Ben, if you run down a beach at low tide on the hard-packed sand barefoot, and you go back and look at your footsteps, your toes are splayed the widest when you're sprinting, because that's where the power is. So whether it's sprinting or walking up stairs, you land on your toes, your metatarsal heads, and your toes splay out when you're walking upstairs barefoot. The toes want to splay out. The feet want to be used. The intrinsic muscles of the feet need to be used, and they become atrophied in most people. So with Peluva, we just said, look, let's let feet do what they're supposed to do. Let's let people reacquire a strong, perfect, balanced gait. Let's let them reacquire agility and mobility and resilience in their feet, and over time, that translates into not just the ability to walk better and longer, but the desire to walk better and longer. I mean, I have so many people wearing Peluvas, walking and thinking, I never felt so good walking. Every step — I'm sort of conscious, semi-conscious, of every step I take, and it feels good. And people look at you

Ben Greenfield

could say Peluva is to walking what sex without a condom is to sex.

Mark Sisson

That's okay, all right. I'll trademark that.

Ben Greenfield

There you go.

Mark Sisson

No, that's a good point. The ability to — like, when we're in Europe, we look for cobblestones a lot, because we call that foot candy. Walking on cobblestones just feels so amazing, so great, as does bouldering on a riverbed. I know you've done that. And so there are a lot of opportunities here to kind of reacquaint your brain with your big toe and with your feet, because the big toe is wired to the brain. There's a direct connection between the big toe and the glute and the big toe and the brain. And without that connection, you know, you go to the gym, and if you're wearing restrictive shoes in the gym and you start doing a leg day, you lose 20 to 30% of your glute engagement just by virtue of the fact that your big toe is not involved in that activity. Which is why — and I know you know this from your bodybuilding days — guys lift barefoot when they do leg days. You know, if you're doing squats or lunges or RDLs or whatever

Ben Greenfield

you're doing now, you can do it without getting kicked out of the gym.

Mark Sisson

Bingo, yeah. And by the way, people would wear socks, right, and say, well, I'm barefoot inside. No — socks still squish the big toe against the other toes. I mean, we make a five-toed sock, which

Ben Greenfield

I was going to say, unless it's toe socks, yeah, yeah.

Mark Sisson

Toe socks, yeah. So I mean, I really feel more strongly than ever that we're changing the way the world looks at strength, foot health, mobility and longevity through footwear.

Ben Greenfield

Well, Mark, you and I actually had our last podcast where we also had like a half hour of talking about foot health. I think this is like your fourth or fifth time on the show. So I'm going to link to all of my other podcasts with Mark, his website — we have a discount for Peluva shoes, that's pretty good — I'll put that in the show notes. So that's all going to be at bengreenfieldlife.com/sisson2026. I'll link to Mark's Untethered newsletter, and now you know Mark's Daily Apple is back up too. And Mark, you're incredible, as always.

Mark Sisson

Oh, thanks, man, you too. You've got to get out here. We'll go paddling next time. I won't put you on the fat bike. We'll just go paddling.

Ben Greenfield

Yeah, I'm game. I'll take on a challenge I can practice for. All right, cool. Thanks, man, thanks for doing this. I'll see you in Florida, hopefully at some point the next

Mark Sisson

few months.

Ben Greenfield

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