JOSH: Hello, and welcome to Clearer Thinking with Spencer Greenberg, the podcast about ideas that matter. I'm Josh Castle, the producer of the podcast, and I'm so glad you've joined us today. In this episode, Spencer speaks with Menno Henselmans about willpower, self-discipline, productivity, and fitness.

SPENCER: Menno, welcome.

MENNO: Good to be here.

SPENCER: Today we're going to talk about something that I think a lot of people struggle with, which is willpower, and also the question of how do we become more disciplined in our lives? How do we achieve better outcomes with things like fitness and health, and generally the sort of thing that we all want to do better at but many of us struggle with. So I'm excited to have you on.

MENNO: My pleasure. I've seen your work and I like it a lot. I think we both come from a somewhat similar background in terms of applied cognitive neurosciences and psychology. So I think it's great.

SPENCER: Wonderful. My first question for you is, there's this debate in the academic literature of what willpower is really like. And some people say, “Willpower is like a muscle. You need to practice and train it.” And other people say, “No. That's the wrong way to look at it.” So where do you fall on this divide? And I want to hear your thoughts about what willpower is really like.

MENNO: The traditional model is that willpower is indeed like a muscle, and that's often called the Baumeister model. The idea is essentially that your willpower is like a vat in your brain that gradually empties with use. However, there are multiple lines of research that show that this model is probably oversimplified and inaccurate in a lot of contexts. It's a pretty good model for how simple it is but it cannot explain multiple lines of research, one big one being, how much you enjoy a task majorly influences how quickly you develop task fatigue. And that doesn't make any sense if we just think of it as a vat being drained in your brain, that at some point runs out, and then you have no more willpower. Instead, it's a more complex interaction with well-being.

SPENCER: Got it. So if it really was running out, then it wouldn't really matter how much we're enjoying it. What do you think a more nuanced way of looking at it is?

MENNO: Well, let's first define willpower. It is the ability to override thoughts and emotions. And I think Michael Inzlicht, that's pretty much his definition. As far as I'm concerned, his views on willpower are the most evidence-based and make the most sense. You had him come on your show, right?

SPENCER: Yeah.

MENNO: Great. So then your listeners will be familiar with system one and system two. System one is the emotional part of the brain essentially, that makes decisions very rapidly, our intuitions. System two is the more rational conscious part of our brain that allows for deliberation, math, and more rational reasoning, but it's slow and effortful. And willpower failure is essentially a clash between these systems; at some point, system two fails. And we can see this in the anterior cingulate cortex, which is very strongly involved in the registration of wellbeing and the maintenance of our attention. And when we exert effort on a ‘have to' task, rather than a ‘want to' task, we can see that system two — the activity in system two, the prefrontal cortex of the brain — fades, and the anterior cingulate cortex as well. And at some point, basically, our attention shifts automatically from the ‘have to' task to other more ‘want to' tasks. It's basically a loss of attention when we're doing something we don't inherently enjoy doing.

SPENCER: Let's use a really specific example because I think it's helpful to illustrate. Imagine someone has doughnuts in the kitchen, and they're working in the other room. And then they have a thought like, “Oh, man, a doughnut would be tasty right now.” But they've told themselves they don't want to eat too many doughnuts. What is the exertion of willpower there? Is it when they catch that urge, and then they override it with their system two by saying, “No, I've committed to not eating a doughnut, so I'm not going to do it now,” and then they redirect their attention to something else?

MENNO: Basically, system one in this case — our more emotional system — gives us hunger, and that says, “Doughnuts. Eat.” And we need system two to then say, “Well, lots of calories, unhealthy. I prepared other foods. Maybe don't eat the doughnut.” But system one, our intuition — if you like doughnuts at least — it just says, “Eat.” We have to suppress that urge and that is the exertion of self-control. That is willpower (willpower and self control, often used interchangeably). And if you have to keep doing that for a long time, then basically that conflict of suppressing system one — of suppressing the urge, the hunger — eventually makes us less well-off. It decreases, as psychologists would say, our positive affect. Basically, it makes us less happy, reduces our enjoyment, and deteriorates our mood. And at some point, that can become critical to the extent that you give in to the urge, and that's what we call self-control failure.

SPENCER: I feel like there's something intriguingly paradoxical here where, if I imagine someone resisting that doughnut and saying, “No, no, I committed to this diet,” I also imagine at some point, it might flip and they might actually resort to using their system two to justify eating the doughnut. At some point, they're like, “Well, you know what, I was really good yesterday, and I actually did more than I needed to do yesterday. And I'm gonna exercise later today anyway. So I should go eat that doughnut.” Do you see what I mean? They actually will start convincing themselves that it's fine to do.

MENNO: Yes, system two can post hoc (afterwards) be used to rationalize the choice, which wasn't really a choice at all. In fact, basically, you could say that you were unable to stick to your choice. But we often find that people do rationalize their decisions later on to (again) minimize this cognitive dissonance. That's a big part also of (in general) how humans behave. And why self-control fades is that, when cognitive dissonance of any form...so we have two ideas in our heads, or our actions and our ideas are not congruent with each other, or when system two wants something different (in the case of self-control), that creates cognitive dissonance, and that's inherently unpleasant for humans. And that's a good thing because, normally, if you have two thoughts or two ideas in your head and they are not congruent with each other, that would be irrational. In fact, the definition of rationality, by most economists, is that your ideas are congruent with each other; they make sense. If you believe A, and you believe B...you cannot believe two things that say something different.

SPENCER: It's interesting to think about the different states of the world that your mind is imagining at that moment. Because you've got state one of the world where you go eat the doughnut, but then you feel guilty about it afterwards, and you're further from your goals. State two of the world, you don't eat the doughnuts, you don't get that tasty deliciousness, but then you feel good about the fact that you avoided it. But then there's this state three, where you go eat the doughnut, but then you justify it to yourself so you don't feel bad about it because you've rationalized it away. Now it's true, you're still further from your goals. But if you can convince yourself you're not, at least it seems to your mind like you've gotten all the things you wanted: you didn't have to feel guilty and you got the delicious doughnut.

MENNO: Yes. And that's basically where the human brain deviates from computers and perfectly rational machines, where we are very flexible in how we deal with this cognitive dissonance. We don't often end up with the most rational or most consistent choices. But the most important part of what our brain does is often to just make us feel good, to rationalize why we do things and to make us feel better, even if our choices were not necessarily optimal in an economical sense.

SPENCER: How does all this relate to self-discipline? How do you think about what self-discipline is?

MENNO: I think self-discipline is essentially the same thing as self-control. We have a lot of different words about these concepts but I think, neurochemically, we're talking about the same processes. So when someone says, “I have a lot of discipline. I have a lot of self-control. I have a lot of willpower,” I think these things are all essentially referring to the same thing.

SPENCER: Got it. In practice, what do you think the best ways are to become more self-disciplined?

MENNO: The funny thing is, I don't think you can. There's a lot of research, training self-control and, in fact, training almost any kind of innate ability, whether it's executive functioning, the ability of the brain to allocate its resources (to put it in abstract form), or working memory, the ability to hold a lot of numbers or names in your brain briefly while you're doing something else, and many of these inherent deep processes in the brain. You cannot train them. You can become better at specific tasks. But most meta-analytic research finds that, if you try to extrapolate that outside of the very narrow context in which you are training, you're not actually improving the brain's overall functionality. Just like IQ, you cannot really improve your IQ much. Now you can improve...it's applied to use a lot with education, for example, but someone's ability to actually score better on IQ tests (other than just performing the exact same sort of IQ test) is quite minimal. The whole idea, in fact, that you need to improve your discipline is flawed, because most research finds that people that are most successful in life, or in academics, and in most fields (we have the most research on academics) finds that they are not necessarily more disciplined; they rely on it less. And in fact, generally people that have more discipline use it less than people that have less discipline. It's a lot more about being organized, planning your life and finding ways to avoid temptation rather than to white-knuckle discipline yourself through it and see where you end up. In principle, that's what most people do with dieting. They fail a lot, and they try harder, but they keep failing. The success rates of diets, for example, is absolutely abysmal. The attrition rates of most diets beyond six months are really bad, especially 12 months. Weight regain rates are nearly 100% And some research finds that people that diet more gain more fat and weight over time, as opposed to people that don't even try.

SPENCER: You're saying that the most disciplined people often try to avoid relying on self-discipline. So that's like, don't even buy the doughnut in the first place. If you find it easy to not buy the doughnut, but you find it hard to avoid eating the doughnut once you bought it, then just don't buy the doughnut, right? Don't put yourself in that position. What are some other ways that we can try to avoid relying on self-discipline?

MENNO: It's a lot about modifying your environment. There's a lot of literature on nudging that is more about how other people do it but you can also do it for yourself. For example, smartphones are a really, really big one. I think the most common types of distractions in the office for people are, one, social media and, two, smartphones or, two, news (social media and smartphones are, for most people, the same thing). If you use apps, for example, if you find yourself basically being addicted to Instagram, you can install one of those apps that blocks Instagram when you're working, or that makes it more difficult to access it. And turning off notifications is a really big one. A lot of people are basically clustered to their phone nonstop, the whole day. And there's no way you can be very productive if you're constantly being bombarded with new emails, new WhatsApp messages, new likes on Instagram. You need to be able to focus because humans are very bad at multitasking. So a lot of it is about structuring your environment. For example, your homepage, if you boot up your browser, do you get to a news page or do you get to just Google search or what you were doing the last time? I think if you get to a news page, there's (of course) a big chance that you're gonna end up reading what's on that site. And I'd say the less natural discipline you have, the more you should think about structuring your environment and your lifestyle and your schedule, your diets and everything in life in such a way that you won't have these distractions in the first place so that you don't need the discipline.

SPENCER: When it comes to trying to cultivate self-discipline, there are all these self-help books that are about, “Oh, you can just toughen up. It hurts, but just do it anyway. Push through.” And it seems to me like what many of them are trying to do is to build this surge of motivational energy, where you're encountering this difficult thing, and you want to give up, but then you just surge with this thought in your head that gives you that energy to push through. We see this all the time in things like Tony Robbins kind of seminars and stuff like that. I'm wondering, what do you think of that approach to trying to be better?

MENNO: I figure it doesn't work at all. I think, as you say, it creates a surge of self-efficacy (as psychologists would call it), belief in your own power, your ability. You are temporarily inspired but, as soon as that emotion wanes, so does any chronic effect on your productivity, your well-being, or your life in general. A good example from my clients: if a new client comes to me for coaching to get more muscular or leaner (because I do fitness coaching), if they come to me and they're like, “I'm so excited, I can't wait to start. I'm going to kick ass. I'm going to change my entire life. Everything's going to be different,” that is actually often, for me, a sign that they're going to struggle. They're going to have problems with diet adherence, because that's not true motivation; that's enthusiasm, and enthusiasm is very different from intrinsic motivation. Intrinsically motivated people often don't shout it from the rooftops; they just do things. They're motivated, they're doing these things, they almost take it for granted, in a sense. And I also find that these kinds of people sometimes literally cannot wait (because I generally have a waiting list) so they go to someone else to get that done already. And when they do start, some of that enthusiasm may have already died out, and they don't have that sustained motivation. Whereas, some of the people I experienced surprisingly high levels of dedication from, they actually did not give any signals for this. They just did things. And I would ask them, I was a little skeptical. I wasn't completely clear on what they were doing, and then I had to check up on them and ask for diet logs. And they just very casually brought them, “Here's my diet log. This is exactly all of the galleries, the weights and inputs for the last two weeks. And this is exactly what I did.” You don't hear from them for a week, and then you send an email. “Yep, I followed all your marching orders to the letter, with military precision. That's it. I did it. What's next?” I think there's a very big difference (for people to realize) between enthusiasm and true motivation.

SPENCER: Do you think that's true at the very highest levels? If you take, let's say, an Olympic athlete who's training six hours extremely intensely every day and eating in a completely optimized way. How do you think that they get to that level? You think they're just born different and they're able to do things most people can't? Or do you think it's more about this incredible reshaping of their environment so that they really have almost no temptation to do anything other than the perfect training routine?

MENNO: No, I don't think it's quite like that. I think it's similar to habits and routines. And there's also research showing that, for example, liking a specific exercise does not predict adherence as much as the results you get from it, or the utility thereof. Basically, if it works, that's more important for people generally, than if you really like it. And most top athletes — not most perhaps, but a lot of top athletes, myself included — actually aren't really enthused to go to the gym or to train. I just go because I know my life is better when I go. I'm not particularly enthusiastic about taking showers or brushing my teeth either, and for me, those things are very similar to physical exercise. They're things you do because you know your life's better when you do them. A lot of top athletes that I've talked to don't enjoy their training. In fact, some of them even dread their trainings. There's a nice quote by some of the actors from the movie “300” where they said, “If you're not nervous before you train, you can train harder.” So this idea that some people just really love physical exercise — there's something that drives them for sure and research finds there's genetically explained variance in exercise motivation — but it's not like people really enjoy putting heavy weights on their back and squatting down and feeling their muscle fibers almost tear and metabolic stress surge through their muscles, etc. It's not really an enjoyable activity per se, to exercise. You're — almost by definition — pushing yourself beyond your comfort zone and doing something you don't like.

SPENCER: We talked about them being motivated by results. Is that more short-term results, like they're seeing themselves improving their times or seeing their strength improve? Or do you mean more like they're trying to win the gold medal, and they just keep that in mind every day when they're doing that difficult training?

MENNO: Some of them have goals like that, like specifically winning a gold medal. But most research finds that social rewards — so in the case of the gold medal, the gold medal itself — is not so motivating, but it is very motivating to know that you might become the best in the world at something and everyone will perceive you as such. That's a very strong motivator and (two) is a growth mindset. I think for high-level athletes, the social rewards might be a bigger factor than for most individuals. If you look at someone who just goes to the gym to look good, and maybe they do low-level modeling on the side or something, but they have an office job that they're doing for their income. I think for those individuals, a growth mindset (as Carol Dweck calls it) is more important, the idea that you're constantly striving to better yourself, rather than that you're chasing this six-pack in six weeks, or a gold medal 350-pound bench press. These things are kind of empty, they don't give you actionable information. It's more important to have direction to know that you want to be stronger, rather than to have a certain strength level, for example.

SPENCER: I usually think about growth mindset in the context of when you fail at something. If you fail and you have a growth mindset, you think, “Okay, well, the fact that I failed means I just need to work harder and practice more.” Whereas, with a fixed mindset, you fail and you think, “Oh, this means that I'm just not good at this. And I should probably give up.” Is that how you think about it as well?

MENNO: Yeah, they are two sides of the same thing. Definitely, the aspect you say makes a lot of sense in terms of how you cope with failure and how you see yourself. But it's also about goal- setting, which is probably more related to fitness. Like I just described, a growth mindset would be, you want to be stronger, and people with a more fixed mindset...or I guess the contrast here would not so much be a fixed mindset, but a performance goal, as it's called. A 350-pound bench press would be a performance goal. And “I want to be stronger every time I go to the gym than the last time,” that would be a growth mindset. And a growth mindset, you can also contrast that, as you said, with a fixed mindset; that's even worse where, with a true fixed mindset, people think they can't even really improve. That's another very fundamental problem that you would have to tackle first, because it's simply objectively not true in almost any aspect.

SPENCER: I see. So we can almost rank-order them the way you're describing it. We've got at the bottom, the fixed mindset saying “I failed. That means I suck, and I'm just not good at this.” And then above that, you have a performance goal, you're like, “What's motivating me is to be able to bench press this many pounds.” And then you're saying above that is this growth goal where what's motivating me is to continually get better. And if I can top whatever I did last week, then I feel great. Is that how you think about it?

MENNO: No, but that is a good insight. I've never really thought about rank-ordering them in the same category but I think it makes sense. Yeah. And if you consider the ranking in terms of general success you will have at achieving the goal, then I think that, yeah, it makes perfect sense.

SPENCER: You also mentioned that a lot of top athletes are socially motivated. Do you think that that is a motivation that is a good thing that we should lean into? For example, some people might say, “If your whole reason to do this is just because you want to impress other people, maybe that is just striving to look good to others, and maybe that's not the ideal form of motivation we should seek.

MENNO: Yeah, that's a good question. I think I generally adopted a utilitarian perspective on this where, if the activities you do (regardless of why you're motivated for them) makes you better — for example, if they make you live healthier, they make you exercise — then I'd say, “Don't question it.” Intrinsic motivation itself is a bit of a black box for most people. I don't really know why I'm more motivated than other people to go to the gym, for example, and why I'm not motivated to, for example, play the piano, despite my parents really wishing I had motivation for it. I don't know, it's something in you. But I don't particularly care that I'm not playing the piano, and I do enjoy looking better, feeling better, and being healthier. So I think, for a lot of these things, don't question it if it suits you. But it is good, I think, to keep in mind — especially for athletes — what the long run is, and to maybe realize for yourself (to have some self-awareness) why you're doing these things. And if you know deep down that it's so that other people can see you and they think you're glorious, okay, but make sure that doesn't consume you and doesn't make you destroy your body, for example, to get a gold medal one year — okay, you have the gold medal — and then for the next years of your life, you're crippled.

SPENCER: Now for those who've never seen a photo of Menno, Menno is jacked. Menno is in just insanely good shape. And so I'm wondering what drives you? What motivates you to be so fit?

MENNO: Yeah, like I said, I don't really know. I mean, objectively, I know I enjoy my life more when I train than when I don't train. I can cite all the things like: exercise boosts creativity and productivity, it's a good break option, you're healthier, it increases well being. And in the end, that's the most important thing for me, anything that increases subjective well-being, you should do. But other than that, why this and why not another sport? It's hard to say. I do actually enjoy other sports. Probably, I could have done other things. So it's also a bit of environmental influence or luck, probably, that I ended up with strength training, rather than some other sport. But yeah, it's hard to say why you have intrinsic motivation for a certain thing, and not another thing.

SPENCER: So if you wake up in the morning, and you're just like, “Oh, I'm tired today. I don't feel like going to the gym. It's gonna be a pain in the ass,” what do you do to get out of that funk and go to the gym anyway?

MENNO: Well, for one, I try not to even think about these things. I think it's not productive to make the decision every day. I know I made the decision to do it at some point. If I reflect on it, I know it's the right decision. But I don't actively think about the decision most of the time. If I do have it, then there is certainly a bit of willpower that you just have to exert. Another trick that you can do if you're feeling down, is to use something else to motivate you and make you feel better. Because often, when you feel better, you will be motivated to make better choices again. Taking breaks is a really big and successful way to achieve this. You can also take caffeine. A nice rule of thumb that I give to some of my clients is, if you don't feel like going to the gym, take your pre-workouts (like a Red Bull or a coffee) and, if after an hour, you still don't feel like you want to train, okay, feel free to skip it. But most of the time, you will sense that, if you take some Red Bull, you watch a series, something you like — for some people, maybe they watch workout motivation or sports or whatever on YouTube or something and then they find the motivation comes back — and then you go. Another thing you can do if you need a foot in the door technique, is to tell yourself, “You always go but if, after a while, you don't feel like actually doing the workout, you can leave again.” That's also a trick that can help a lot because almost always, when you're warmed up, and your body is in a psychological state of arousal, you'll find that you will want to do the workouts.

SPENCER: It's amazing how much momentum we have as humans. If you've done something every single day, you're probably just gonna do it the next day. And you know, if you've already bothered to go to the gym, you're probably just gonna exercise. You're probably not gonna leave, right?

MENNO: Definitely. And yeah, that's habits. Habit is a huge part of it. Like I said, I don't often reflect on the choice at all. It's just something you do. And at first, it's hard. But the nice thing about the human brain is that, with habit formation, these things at some point become automatic. And it doesn't matter if it rains or whatever, you go to the gym because you always do. You don't even think about it. And it's the same with brushing your teeth, showering in the morning (if you shower in the morning). You don't think every day when you get out of bed, “Today, shall I shower or shall I not shower?”

SPENCER: Right, it's like the ultimate exercise routine is one you never even question. You have a good routine and you never think about it. You just do it. You execute.

MENNO: Yeah, it's like you're putting your success on autopilot.

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SPENCER: Switching topics, a lot of people think about productivity. They want to squeeze every bit of productivity out of themselves that they can. I'm curious to hear some of your thoughts on that. How can we be more productive, but also, is there too much emphasis on trying to be maximally productive?

MENNO: Yeah, definitely. I think productivity is very important. It can backfire when productivity becomes the end, and it should be the means. Productivity should always be something you do to acquire other things, or something you enjoy doing, and then you just become better at it, and then that happens to make you productive. I think those are very fruitful ways to be as a person, to have your work-life balance. At some point though, productivity itself starts consuming you, confusing the means and the ends. But I think for most people, the creation and being productive and helping others, those are very intrinsically rewarding things for humans.

SPENCER: Could you give maybe some examples you've seen where people make productivity the end rather than the means?

MENNO: It's common in America, I would say, and especially in Japan and some Asian countries. Basically, I would say, if you're sacrificing sleep, then you probably should reflect on your current structure of work-life balance and everything. Because I think it's almost impossible to actually become more productive by sacrificing sleep. Your mental capacities are so much lower when you're sleep-deprived, and they are cumulative. Research finds that after 8 days of sleeping 1 hour less than you need, the effect is about the same as if you have missed an entire night of sleep. It feels as if you have pulled an all-nighter. So for one, it doesn't work. Also, research finds that during the New Deal (New Deal was in America) and in England, there was also a series of labor laws, and a series of experiments by Ford Motor and some other big industrial companies in the early 1900s, late 1800s. At various locations, they either experimented with, or had laws that changed the number of work hours gradually, from 80 to 40. And in almost every instance, they saw an increase in productivity. So not only could they do the same work in less time, they actually saw that, if you have people that were working 80 hours a week — even simple work like factory work — you move that to 60, and then you move it to 40, then you're going to have an increase in productivity. So even factory workers, they're going to produce more automobile parts, for example, in literally half the time.

SPENCER: I've wondered about this with things like investment banks where you have people working 80 hours a week. It actually happens a lot (I think) in investment banks, and could that possibly be a good use of time? That 80th hour, are you really better off working, rather than (say) sleeping or just relaxing and recovering? It seems totally nonsensical to me just on a productivity basis.

MENNO: Definitely, I think a very big part of it is inefficiency. When the deadline comes up, everyone has to work and you all have to be there at the same time. There's also research that office workers generally have to spend eight hours in the office, but their actual productive time is not even three hours. And most of that time, like I said, goes to social media usage, news websites and — my personal favorite and literally in the top ten of other sources of time that people anonymously admit to spending time on — is finding other jobs. If you employ office workers, if you're an employer, most of your employees are going to spend a very considerable portion of the time you pay them — because they have to be at the office, you're mandating that — looking for other jobs. You're essentially paying them to look for other jobs.

SPENCER: I've heard of these rather unethical, but also hilarious, cases where people would actually hire other people to do their work, and the companies didn't realize it for a long time. Eventually, people outsourced their own work to people being paid less to do the same exact thing. It's kind of wild, what people get away with.

MENNO: I think as an employer, I would personally not even care about that. I tell my employees or the people I work with, that you get the job done. That's what I care about and this is what I want you to do. I don't necessarily care who does it. I don't care how you do it. I don't care when you do it. I don't care where you do it. Well, some things are, of course, time-sensitive but as long as you to do it before (say) deadline X, as long as you deliver the right product, or you do the right research, you give me the right overview of the scientific literature on this and this, that's what I want. And there's a very big difference in how you motivate people where you can either tell them what the goal is, or you can tell them what to do. And you have to be very careful with that, because if you tell the wrong type of person the wrong type of goal, it doesn't work well. Now, if you micromanage a very successful person, if I would work with you, and I would tell you, rather than what the goals are, I'm just going to tell you (without saying why), you have to perform these steps, you have to operate this software, click on this, click on this, then you click on this, you're going to find it dreadful probably. Whereas, if you have someone that's underqualified for a role, and you tell them, “I just want this,” then they're going to be lost and they won't know what to do. I think it's very important to have the right vision and the right goal structure that you give other people you work with.

SPENCER: I've noticed big individual differences in productivity. For example, someone I know really well, she gets a shocking number of hours of work done a day, I think, that's way beyond most people's capabilities. And I think for other people, it's more like three good hours, and they're like, “That's a good day.” I'm curious if you've seen the same thing. And if this is true, I wonder if this is also partly why people will push themselves so hard, because they're trying to catch up to someone who just is much more productive than they are.

MENNO: Yeah, I think most of the variance is optical. So most of the highly successful people I've talked to, they don't work — like actual work — more than four hours a day. I think I'm a relatively productive person, but if I actually add up all the really productive time I spent on something per day, if that's four hours per day consistently, that's good, that's very good. I'm literally doing what I love in life. So I may be slightly above that. But I think for the vast majority of people, if you can spend three productive hours, three to four, on something per day, that's already great. And most of the difference is that some people take longer to do it. Some people take more breaks, and they tell themselves, that's a break. For example, I play chess in between sending emails, and I don't necessarily count that as work, but it is, sort of. I'm not really doing something else. I'm sending an email. I do one bullet match, one email, one bullet match, one email, one bullet match. And so I'm constantly on the computer, but in the end, probably only half the time is actually spent productively working. Do I then say I've been working for the last four hours? Or do I say I've been working for two hours and playing chess half the time?

SPENCER: Yeah, it's so tricky to think about what it really means to be doing work. Because I find, in a given hour where I'm sitting at my computer working, and I'm not checking social media, I can have a huge variation in how effective I am at getting stuff done. Some days, it just feels like I'm operating more slowly, I'm not doing very important stuff. Other days, I'm working on something really important, and I feel very effective and I get a lot done. So even just in one hour of actual work, sometimes I feel like that hour is 10 times more productive than at other times. So what does it really mean to work? How much are you really working? I just think it's hard to think about. And then you take someone like a waiter or waitress and they have a shift and, well, they're really working during the whole shift; they're on duty, they're doing stuff. They might have down moments, but even in the down moments, it's not like they can do anything fun. They're just forced to sit there and wait.

MENNO: Yeah, if you have that kind of job there, you're forced to be productive, but it's not a very demanding level of productivity. On the other hand, most of the waiters and waitresses I've talked to, especially people that do it as a side job at college and the like, they do know that it's quite draining, and you're really exhausted, not just physically and mentally, precisely because you don't have breaks.

SPENCER: So other than trying not to work too many hours, past the point of it actually being on-the-margin helpful, do you have any other tips for trying to be more productive?

MENNO: I think it's most important to have very deliberate productivity. So when you're working, you're really focused on work, you've disabled notifications, anything that's not truly urgent...your phone's off, your notifications are off or whatever, as much as you can possibly do it. If you're working on Gmail, for example, I recommend to use the minimalist outlet, anything you don't need to trip it. A very, very big one (I think), is not showing the email text in emails because it enters your working memory and, “Oh, this person said this and this,” you start thinking, “What if it's this? What if they don't agree?” You can't get rid of it. Basically what you want to do for every email is, you read it, answer it. If you're not going to answer it, don't read it, nothing, not at all. I think that's a really big one.

SPENCER: So you should just think there's a way to turn that off so you don't see the first part of the email before you click it?

MENNO: Yeah, you can just see the title.

SPENCER: Ah, got it. And what was that other suggestion you had about, it was some kind of plugin or something?

MENNO: Yeah, Gmail has a minimalist frame. If you go to the settings, you can remove the chat, you can disable email text showing.

SPENCER: Oh, nice, nice.

MENNO: You can, in general, make the whole frame very minimalist and show only things that you exactly need. Because if you just have default Gmail or, even worse, some other email client — I think most people should switch to Gmail if they haven't yet, because it's objectively the best, fastest, most reliable, and the layout allows for perfect customization — but yeah, you basically want to get rid of anything you don't need. And it goes for your desktop, your browser, the background of your mobile phone, all the apps you have on your mobile phone, anything, you want to make it minimalist, remove all the distractions, make it very focused. For your desk, it's the same but you do want things that make it enjoyable. You could have a plant, pictures of family, that can be good, but don't have a bunch of paperwork laying around of other projects that you're currently not working on, for example.

SPENCER: I may be more sensitive to this than some other people. But I have found even clutter on my desk, I find it distracting while I'm working. I have trouble getting as focused.

MENNO: Yeah, there's actually research showing it does reduce productivity.

SPENCER: Changing topics again, a lot of people want to lose weight or get leaner and the standard way to do this is to go on a diet. I'm curious, what are your thoughts on going on a diet?

MENNO: I think the approach — when you say ‘going on a diet' — it's already, in a sense, a wrong mindset, although it's such a common vernacular now that I often also use the phrase. When you say, “You're going on a diet,” you're implying that you're going to make changes that are temporary. And if there's one thing that research on dieting shows is that people need to focus on the long run; you want a lifestyle perspective. And funnily enough, the original meaning of the word ‘diet,' which comes from Greek — diaita — it meant way of life. It never meant six-week periods of unsustainable suffering to get a six-pack for my next wedding. That whole idea is why many people fail, because obesity or being overweight, or in general, having more body fat than you would like, essentially comes down to the fact that there is a long-term imbalance between your overall energy intake in life and your overall energy expenditure. And if you're not tweaking that balance in the long run, then you're just gonna end up in the exact same spot. Sure, you can change your lifestyle around for six weeks, you get lean, but if you go back to the same lifestyle that got you fat in the first place, you'll get fat exactly the same way. In fact, you're probably going to reach the exact same weight (which often happens to people). So you have to make long-term sustainable changes, and you don't think of “Can I do a water fast for this time? Or can I do a keto diet? I'll go vegan for the next weeks.” You have to think, “How can I modify how I currently eat in a way that I still enjoy and is still satiating, but allows me to reduce my overall average energy intake over time?”

SPENCER: So what are some modifications to diet that you think people tend to be successful with?

MENNO: A couple of the big ones are high protein. High protein intake is very helpful for essentially everything, for health, for fat loss, for muscle growth. It has a thermogenic effect. It aids muscle protein synthesis. It's basically a win-win for whatever your goal is. Second is high fiber intake, at least for fat loss. For muscle growth, it's not quite necessary. But for health and fat loss, it's a huge win. Most research finds sustained response effects of fiber intake on both adiposity — so body fat level — and health outcomes up to quite high levels. Most meta-analyses find benefits in the 30s, 40s, sometimes nearing 50 grams of fiber per day which, for most people, is a lot more than they're currently consuming. And just overall more whole foods-based diet choices. And then when you've got those fundamentals down, there's a lot more fine-tuning to do. But those things I think, for most people, are the really big bang for your buck. If you've got those in order, then you're probably not going to be overweight already. You're going to be at least decently fit, healthy, not necessarily like a photoshoot, but you'll have the basics in check.

SPENCER: Okay, so basically increase protein, increase fiber and eat whole foods. Can you elaborate on the whole foods recommendation? What do you mean by that exactly?

MENNO: Yeah, it's a bit of an undefined term. Whole foods, generally, you eat things that are closer to how you would obtain them in nature, compared to things that are very hard to discern what originally the food was. If you go to a tree, you pluck a banana, that's a whole food. But if you have a banana smoothie, that's processed. And there are degrees. Certain foods are basically impossible to consume, like grains. The human digestive tract does not really lend itself well to consume those in raw form. So you need to have them processed into bread or pasta, for example. But then whole grain is generally better than refined grain, or more processed grains. So generally speaking, the more you process food, the more fattening it becomes because you're generally increasing the energy density of the food, and you're reducing the satiety index, and those things often go hand-in-hand, so you're making it less satiating or more caloric per unit of food.

SPENCER: I see, so if you take fruit and you eat it versus if you put it in a smoothie, what's happening is you're probably removing some of the fiber and you're making it higher calories per ounce or whatever. And also, it probably gives you a greater jolt of excitement when you taste it, which also kind of makes it harder to stop. Is that the idea?

MENNO: Yes, and there are also mechanical factors. For example, satiety is influenced by oral processing. Chewing on things actually sends a satiety signal to the brain. And if you're not chewing on things, then you're not gonna get that satiety signal. So that's why liquid energy sources are almost always more fattening, because they're more caloric and less satiating, relatively speaking, than the same foods obtained in solid form.

SPENCER: The thing that I struggle with when it comes to thinking about what diet advice people should have, it just seems like everyone has their own theory of diet. You've got the people who say, “Cut carbs,” and you've got the people who say, “Do intermittent fasting,” and you've got the people that say, “Oh, no, all you need to do is cut sugar out of your diet and don't eat, starchy simple carbs.” And there are so many different theories floating around, I just wonder, how do you make sense of it all? And how do you arrive at what you think is actually the truth about this stuff?

MENNO: I think there are two important concepts. One is to be evidence-based. And I think a general good rule of thumb is to mostly get your information from sources that either directly or indirectly cite their claims with scientific research. In my book, if you have the ebook release, you can actually click on everything, and it will literally take you to the scientific study that I used to support a certain thing.

SPENCER: Which book is that of yours?

MENNO: The Science of Self-control. And in the hardcopy, I just reference it and there's a huge reference list at the end. So that's, I think, ideal. And then you can have, for example, Kahneman's books, which are also great. He doesn't cite a lot of the literature directly. But he is a researcher; you can go to his ResearchGate accounts, for example, and look up the research. He does cite some of the studies that he's actually doing. Or then you can have, for example, you, where you interview someone like that, or me. And in the end, the information that is out there has a basis in evidence and there are degrees of it. But it's really important, because a lot of sources, they literally just pull theories out of their ass. There's no basis for it, there's no evidence. There's no quality control or anything. Anybody can say anything, but it's your responsibility — especially these days — to filter your information, to make sure that...yeah, of course, if you're just going to ask 100 people's random opinion, you're gonna get 100 different theories. But if you narrow that down to, for example, scientific researchers, or people who have excelled in a certain field, then actually you're going to be much closer to a consensus, often. And I think if you just do that, then you're already way, way, way ahead of the game. The other thing is that most people focus too much on the specifics, especially when it comes to dieting, for example. We just talked about principles — higher protein, higher fiber — we didn't even talk about concrete food choices. We didn't give a name to the diet. We didn't put time frames on it. We didn't talk about any numbers. We're talking principles. If you understand the general principles, then you find that many dietary approaches are just certain (sometimes even arbitrary) applications of these principles, and there appears to be a lot of variance. But if you understand the underlying principles, then much of that variance actually starts to make perfect sense, and it's not so different as it may seem.

SPENCER: I'm trying to get in the minds of the listener here. And I think a lot of my listeners like the idea of, yes, you should be scientific, you should use evidence. I think they're all behind that. But I think the tricky bit is, they also know about the replication crisis, and they know a lot of papers don't replicate. And they know there's tons of studies that have bad methodologies but are published in good journals. I agree with you; you're already ahead of the game if you're looking at the science. But then how do you get to that next level? How do you know what science to trust? How do you cut through the fact that everything seems to cure and prevent cancer? You can find studies that show coffee is good for you and coffee is bad for you, and the same goes for just about anything.

MENNO: Yeah, the point is, you just have to become an expert. But I think most people don't really need to concern themselves with those things. If you're not going to make something your job or your number one hobby in life, you probably don't need to be concerned with the 20% of things that you may get wrong by following good sources. The fact that you've had the 80% of basics and the things that are well-established right, means that you're going to be well out of the pack for the vast majority of things. For example, for me, I know quite some things about investments and how to invest my money, but I'm not a world expert, and I'm sure I could make my financial investments even better if I spent all of my time researching how to invest my money better. But I'm pretty confident sticking to things like index funds, always going for land or real estate over things that don't have objective value. Stocks generally bring good returns, general principles like diversification, and then you're going to have (say) a 5 to 10% return on your investment generally, and that's good. And if I spent all my time on it, and researched all the papers and the like, maybe I could get that to 15. But it's not worth it, and I don't need to. I'm better off just focusing on my own job — even in this case, literally financially, you could probably run the math — I would be better off just focusing on my fitness coaching, my PT course education, my book, those things, rather than spending more time on that. For most people as well. If you just want to get lean, you don't need to know what the current controversy is on calorie cycling, for example, for maximum muscle growth. If you just want a good basis, a good general physique, but you don't necessarily want to compete, you don't have to micromanage whether your carbohydrate intake pre-workout is 15 or 20 grams. As long as you know that it's better not to train fasted as compared to fed, then you've got most of the bases covered.

SPENCER: So you think that the consensus in nutrition and fitness are actually pretty reliable? If you look at the scientific consensus — it's not gonna always be right — but it's reliable enough that you can just use that as your starting point and not worry about it too much?

MENNO: Yeah, I'd say I was very careful about avoiding the use of the word ‘consensus,' but I think it often does come down to these things — especially if you're a bit more removed, and you just follow the consensus of researchers — I think, yeah, you'll be fine. However, the word ‘consensus' itself (I feel) these days is a bit politicized, like for global warming, for the whole vaccine situation, for the lockdowns. There were a lot of things where a lot of people are now saying, “Oh, there's a scientific consensus,” and it turns out, well, maybe not. I think this is the biggest red flag, when people talk about a consensus as the argument itself and they don't tell you why something is a certain way — they can't tell you what the principle is, they can't explain the mechanism of action — they just say, “Look, everyone feels this way. This is how it is,” then it's more of an appeal to authority. But if you've actually talked to the experts, they're all saying this is the mechanism of action, and they're not saying, “Yeah, we think it's this way because we're all saying it,” — you've heard from 10 experts, they're all saying the same thing — then yes, then I think absolutely, if you're just going by consensus statements from experts or scientists, you'll be very well-off in life generally.

SPENCER: Yep, one thing we might disagree on is, I tend to think that it's very hard to figure out the truth in nutrition in general. And I suspect that this is the case because, first of all, it's hard to do long randomized control trials. It's hard to say, “Okay, you 200 people, you eat this way for two years, and you 200 people, you eat this way for two years.” That's just a really expensive and difficult study to run. And there's just not that many of those studies. And then if you don't do that kind of study, then you're stuck with a lot of observational data like, okay, you're just looking in the population; these people eat a lot of broccoli, and they tend to be healthier, but they also do a lot of yoga, and they meditate and you have all of these confounding variables that make it hard to separate out. So I feel like nutrition is just one of these areas where it's fundamentally hard to figure out the truth. You can fall back on animal studies, but then there's the big question about do the animal studies reflect what's actually going to happen in humans?

MENNO: Definitely. I think that nutrition is a realm that's...it's not in its infancy, but it is a more difficult scientific realm than (say) economics. Then again, if you ask the 100 experts on evidence-based fitness (say) — you have to go by some metric, I guess, by popularity — let's say, you ask the 100 people that are most invited to evidence-based fitness conferences, and you ask them “Do calories matter?” You're gonna get an overwhelming resounding, “Yes, calories absolutely matter.” And there will be some fringe groups that say, “No, it's all about insulin,” for example, and they actually still have a voice even in sciences. But you're gonna get a pretty clear consensus, I think, from practitioners and scientists, that calories are the overwhelming driving force of the obesity pandemic.

SPENCER: There's one more topic I want to cover with you. And then if it works for you, I'd like to do a quick-fire round where I ask you a whole bunch of questions and just get your quick responses. Does that work? All right, great. So last topic before we get to the quick-fire round, how do you think people should deal with cravings? If someone is trying to change their way of eating to try to make a permanent change in their life, they might find, “Okay, I'm getting a lot of sugar cravings,” or, “I really want to eat that white bread or that doughnut,” or whatever.

MENNO: Yeah, I think the most important thing for cravings is that our intuition of satisfying a craving is fundamentally flawed. Research quite conclusively shows that the best way to kill a craving is to starve it. So the best way not to have a craving is generally not to give into it, especially over time, because a craving is not a biological construct. In fact, over 80% of languages in the world do not have the word ‘craving.' And many languages don't even have the word ‘addiction.' That should already tell you there may not be an actual physical correlation of this concept. And in the case of a craving, it's hunger given a social cultural form. You're hungry; that's the underlying actual physical process, the correlate, and this hunger is represented in your brain in the form of certain foods, and then we call it a craving. So you're not just generally hungry, but you are hungry, and you're saying, you want to eat doughnuts (to circle back to doughnuts). And then when we say it's a doughnut craving. However, if you're never exposed to doughnuts, you will never have a doughnut craving. It's good to realize that these things are very much a psychological representation of hunger. And the underlying problem is hunger, not the fact that you have this craving and you need to satisfy it. There's nothing there. Even with chocolates, for example, people who have chocolate cravings, in research, if you give them white chocolate enriched with cacao flavanols, it doesn't satisfy the craving. They want actual brown chocolate, which just goes to show that it's not the nutrients in the chocolate that will satisfy the craving. It is just the fact that you want to eat chocolate until you no longer have hunger. And that means the two most effective strategies are (a.) to get rid of the representation, which is basically like getting rid of a memory. And the best way to get rid of a memory is not to keep enforcing it, but rather to not enforce it. And (b.) to have a very satiating diet, so that you don't have the hunger in the first place. If you're not hungry, you don't have cravings. Even things that are very psychological, like binge-eating, are treated very well by appetite management. So we're inclined to think of these things as being something very special, but it really is just appetite in a certain form. And research quite conclusively finds that people that don't give in to certain food cravings, and they just don't eat the food for a long time, they actually stop liking it, they essentially forget it exists, and they don't have the cravings for it. And even stricter diets are often better. The only thing you have to be aware of is the forbidden fruit effect where you always have to be cognizant that you're making the choice to eliminate these foods, rather than that you're saying, “I can never have doughnuts anymore again.”

SPENCER: Riffing on what you said, it seems like, if you're gonna eliminate a food, you have to eliminate essentially similar foods as well, right? Like if you eliminate doughnuts, but you still eat cookies, it feels like there's still that sugar craving so it may not go away. You're still gonna want sweets. Do you think that's right?

MENNO: Partially, I mean, you might start craving other things, but the doughnut craving will disappear. And whether you get a cookie craving depends on whether you have exposure to cookies, because you're never going to get a cookie craving if you're not exposed to cookies in some shape or form. So if you have a clean diet, you can actually see this cognitively. If you put people in brain scanners like MRI, you can actually see that the reward pathways for when they eat doughnuts decrease if they haven't eaten doughnuts in a while. And if they eat vegetables a lot, then the reward pathways will light up more when they're eating vegetables.

SPENCER: What do you think about really specific cravings? It seems like sometimes people want some really random food. And I tend to think that there might be something to that, like the body has some ability to detect when you're low on a certain type of nutrient. Do you think that there's legitimacy to that?

MENNO: You would think so. We like to think so but it's not true. The research is quite conclusive that cravings for the most weird things don't have a physical form. Chocolate has been extensively researched. Even pica, which is a disorder where people want to eat ice or dirt, doesn't correspond with the mineral deficiencies they might have. There are a lot of lines of research on salt, on sweetened foods, where you find that cravings don't associate at all with nutritional requirements. In fact, they are sometimes polar opposites. Pregnant women in the US often report meat aversion, whereas iron and protein requirements go up quite significantly during pregnancy. So they become averse to foods that they actually need a lot more of. And this is purely a cultural thing because if you compare this with (say) in Ceylon women, Spanish women, Tanzanian women, they have completely different food cravings, and even these ideas like during pregnancy, during the menstrual cycle, research has found no physical correlates. It doesn't correlate with any hormone levels. The menstrual cycle is purely a cultural thing. Like I said, many languages don't even have a word for craving. It's just certain foods that you want to eat, and it's not random foods. It's in a given shape or form, but it's not random food. It's not like you hear people say, “Oh, I'm just dying for some asparagus right now. I really wish I had some asparagus.” There's actually research into which foods people crave, which is called the food cravings inventory. And it's almost universally high-carb, high- fat, low-protein foods, highly caloric, high energy density. Basically, everyone likes junk food. I like junk food, too. I like doughnuts. But I know it's not in my best interest to eat them. So I've designed my diet in such a way as to minimize exposure to doughnuts and consequently, I also don't enjoy them much anymore.

SPENCER: What about cravings that occur right after something like, for example, when you're exercising a lot, and you're sweating a lot, it does seem to me like salt tastes better at that time.

MENNO: Salt is a partial exception, where it's also regulated. Protein and salt are both somewhat regulated in the body where you do salt your food. But for most people, you're never actually on the verge of sodium deficiency. And most of that association is probably driven by the knowledge that you've lost body sodium so you need to replenish that, and associations of which foods you should eat after exercise, which are commonly eaten after exercise, because a lot of people just eat junk foods, they go for Gatorade, for example, rather than salty foods.

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SPENCER: All right, so let's jump into the quick-fire round. I'm gonna ask you just a bunch of, well, not-so-easy questions, some difficult, but I just want to hear a kind of quick response. Does this sound good?

MENNO: All right. Difficult questions with quick responses. I'll try my best.

SPENCER: [laughs] It's not easy. Okay, so I've been told that you should eat after you work out. Is this true?

MENNO: Yes. But it's not like you have to eat directly after your workout. It's rather that you should ensure that your workout and the period afterwards is fueled by nutrients. You can do that by eating after a workout, before the workout, before is actually probably better than after. You just want to make sure that the period is covered. A good rule of thumb is that you want to sandwich your workout in between meals within a 6-hour window. That's a good rule of thumb for most people. So if you train at noon, midday, then you can have a meal at 9am and 3pm, and that's fine. Or you can have a meal at 11am and 5pm, and that's equally fine.

SPENCER: I know some people that take creatine before they work out. What do you think about that?

MENNO: I think it's great that they take creatine. It's better to take it post-workout because then insulin sensitivity is higher and absorption might be better, but it's relatively minute compared to other factors. Creatine is the most established ergogenic aid, meaning performance-enhancing aid. It's legal, it's safe, it doesn't work for everyone. There are non-responders to creatine supplementation. But taking creatine monohydrate in the amount of three to five grams per day, depending on whether you're male or female (with women generally being fine with three and men probably want to take more like five to be perfectly safe) is one of the cheapest and most effective ways you can improve your strength and muscle growth both acutely and over time.

SPENCER: Do you recommend just taking it as a powder mixed in water or what form?

MENNO: That's cheapest. It doesn't really matter because the bioavailability of creatine monohydrate is like 98% so don't bother with the more expensive forms. If you want capsules or powder, I think powder is easiest. You can also throw it in meals, anything where it will dissolve is fine. You want to consume that somewhat shortly afterwards. But other than that, you can put it in meals, you can put it in a shake, capsules if you prefer that. Anything is pretty much fine as long as you get it into your body.

SPENCER: When you're having a good healthy week, what is your typical diet like?

MENNO: Currently, I'm lean bulking (as it's called), trying to put on more muscle without getting fat. That means I have three or four. Currently, I'm still at three meals a day — when I go to higher energy intakes, I often have to go to four — three whole foods-based meals per day. I start the day with Greek yogurt and a form of fruit and then second meal, today I had sort of a Mexican meat avocado bowl with veggies and almond flour pancakes, and tonight –– I'm actually not having sushi –– I'm probably gonna have pesto sauce with whole grain pasta and chicken.

SPENCER: That's like a pretty tasty way to eat. It doesn't sound like you're killing yourself.

MENNO: No, I think that's actually one of the most important things to know, to make your diet actually nice, and learn to cook, and finding simple recipes that you like that are healthy is really important. Because you can't just live on broccoli and chicken breast and white rice all the time. That's not an enjoyable way to live.

SPENCER: What are some common mistakes you see people make when they're doing strength training?

MENNO: Oh, a lot. One of the biggest ones probably for the general population is ego lifting, especially for men. Men are a lot more prone to this, I would say, than women. They sacrifice technique and range of motion for more weight, basically faking their own progression. And that's just more injurious, it's not as effective. And because you're faking your own progression over time, you also don't know if you're progressing, which means you don't know if your program is working, and therefore you don't know how to adjust it. I think that's a really big one that many people are prone to.

SPENCER: Other than trying to push yourself beyond your capacity to lift heavy weights and not using good form, what are some tips you have to avoid injury when strength training?

MENNO: Avoiding injury is mostly about using good technique, finding exercises that suit your body, and moderating your volume appropriately. I think a very big part of it is listening to pain signals. That is a bit of a tricky topic because, if you talk to some physios, they'll say pain is just a psycho-cognitive sensation, it doesn't necessarily correspond with tissue damage. But if you learn to distinguish between a pain for muscular exertion, which is good pain or fine pain, and the pain from (say) a torn ligament or tendon, you can learn to distinguish between those. And listening to those things is really important because for most people (and again, men being more prone to this, in general, more hardcore lifters being more prone to this), training through pain is almost always how overuse injuries start. It starts with just a little ache and it's like, “Oh, no, no, it's fine,” and I often see that. When I ask clients if they're in pain, they don't answer if they're in pain. They say, “I can deal with it.” That's not what I asked. I know you can deal with it, but is there pain? Because if there is pain, or any discomfort, or what you describe as stiffness, or it doesn't feel right, don't do it, switch exercise, go higher repetitions, and use more controlled lifting tempo, and maybe decrease the volume, but preferably do the other things. Because you're decreasing the volume, you're also reducing the stimulus for muscle growth and strength development.

SPENCER: What are your thoughts on stretching? Do you think people should stretch before they exercise?

MENNO: No. Stretching, I think, is probably the most overrated form of physical exercise on the planet. Stretching has been shown in research to be rather ineffective to improve functional range of motion in unrelated activities. It's very ineffective as a means to promote strength development. It does not protect you against injury. Basically, stretching just makes you better at stretching. So for most people, it's a colossal waste of time compared to resistance training. In fact, a recent meta- analysis found that resistance training is as effective, if not more effective (generally more effective, on average), to increase range of motion and to increase muscle length. On top of that, it actually decreases injury risk, it makes you a lot stronger, it makes you more muscular, and makes you look better (well, if you want more muscle, at least), it helps more fat loss, you expend more energy, it's better for your health. It's quite literally, as economists would say, a dominant option, better in every single regard.

SPENCER: You know way more about this than I do. And I have a feeling you might disagree with me on this. But the way that I've come to think about stretching is that I think it's important to do when you have a mobility issue. I had an issue with my shoulder where I couldn't move my arm in a certain way and I found that stretching was very effective to increase the mobility. I would just do a couple of minutes a day and that massively improved my mobility. That's how I think about it. If you can't move in a certain way, then that's effective. Am I wrong on that? What are your thoughts?

MENNO: Most research finds that, in these cases, any form of physical activity works equally well. It's just about promoting blood flow, making the tissue a bit stronger, making you move, rather than the fact that you're stretching, whether it's PNF stretching, dynamic stretching, static stretching, strength training. If anything, strength training would probably be better, pain-free, strength training over a full range of motion. But other than that, yeah, it's just the fact that you're doing something compared to nothing,

SPENCER: Right, so use the movement, push it to the edge of the limit of your motion, again and again; it doesn't so much matter if it's stretching per se.

MENNO: Yes. And in fact, what you just described, if you do that with weights, we call it strength training, but if you do it without weights, we call it stretching. Full range of motion strength training is in effect, making muscles from their fully contracted to their fully lengthened position. That's at least the goal, under load, until you're close to muscular failure. And if you do that with a lighter weight, then we might call it dynamic stretching, or if you do it statically, we might call it static stretching. But essentially, weightlifting is a form of weighted stretching.

SPENCER: That's a good way to put it. What about warming up? What are your thoughts on that?

MENNO: I think you should warm up. But research showing you should is actually not nearly as convincing as most people think. And the effect on performance is also not nearly as large as most people think. You'll warm up — putting things very roughly here and generalizing a bit — most people can probably have their warm-up be five minutes, 20 minutes absolute maximum. I think for most people, five should be fine. And it should mostly be to literally increase your core body temperature, and you can speed that up by wearing a hoodie and just dressing warmly. Most of the effects are literally the result of higher body temperature. It increases the velocity at which your neural signals can travel in your body, it increases many aspects of how your oxygen and blood are delivered to muscle cells, it makes muscles a bit more elastic and generally speeds up chemical reactions. So most of the effects are literally the result of the higher temperature and you don't have to be very fancy about it.

SPENCER: That's fascinating. I'd never heard that before. Some people argue that you should do a form of warm-up that mimics the exercise you're actually going to do but at a slower speed or with less weight, or whatever. Is that BS, from your perspective?

MENNO: That's very effective, because you're warming up the tissues that need it. You're rehearsing the movement pattern so it's like technique practice. And for strength training, this is the reason that most forms of dynamic stretching and everything, are redundant. Because if you're gonna squat, then you could basically do a dynamic stretch that's extremely specific to the squats, namely, squatting with less weight. So you're just doing the exact exercise, you're adding progressively more weight to it. And it functions as a form of very specific warm-up, motor pattern rehearsal, dynamic stretching, everything all at once. If you can do this, as you can do in the case of the gym, yeah, that's perfect. The only reason I think something like dynamic stretching can be useful is for an athlete. If you're going downhill skiing, then you can't exactly tell the slope of the mountain to reduce its incline or something; you can go down or you don't. And before that, you can do something like dynamic stretching because you don't have a better alternative, essentially,

SPENCER: That makes sense. So if I'm weightlifting at the gym, I can do more reps with a lighter weight, or I can do fewer reps with heavier weight. How does one make that decision? How do you think about where to be on that spectrum?

MENNO: There are a few factors to consider. But it's not a very important decision. Generally, training heavier is better for strength development, but it's also more injurious. I think, in practice, those are the biggest aspects. For advanced lifters, there are a lot more aspects: periodization, undulating periodization, varying rep ranges. For most individuals, beginner/intermediate level, as long as you're going close to failure — you're doing as many reps as you can, for example, between five and 30 repetitions — muscle growth is going to be similar. If you do three sets of five, three sets of eight, three sets of 12, 20, even 30 (at 30 RM, I'd say, if you can do 30 every set, then your first set evidently wasn't very difficult), but muscle growth is actually going to be similar. So there was this idea of a muscle growth range or hypertrophy zone, and that turned out to be bunk, basically. The most important thing is, if you want to get stronger, you should train heavier. And even that is mostly because it's just a specificity adaptation. Like if you want to get stronger, we often think of one RM at maximum strength, and then you want to practice maximum force output. But if your ideal strength is to do a CrossFit-type performance, where you do a lot of repetitions in a certain amount of time, then it's more strength endurance, and you can actually improve that more sometimes by doing higher reps. So performance-wise, the human body very much adapts to exactly what you do, and it gets better at exactly that.

SPENCER: Got it. So you want to make the exercise you're doing as close as possible to the thing you want to get good at. But other than that, it sounds like, as long as you're pushing yourself to essentially muscle failure without injuring yourself, you're pretty good. Whether you're doing 20 reps or five reps, just make sure you get to the point where your muscles are totally exhausted. I believe I actually heard this idea from you on a podcast of, if you do one set, let's say you get ten reps as your max, and then you do a second set and it drops precipitously, like now you can only do three, that that's actually a sign of something about your strength or development. Could you elaborate? What does that actually show you?

MENNO: It's a measure of the fatigue index, as exercise scientists would call it, more informally called work capacity. Basically, how much your reps drop off across sets is a measure of how fatigued you are. So you can basically say if your repetitions go from ten to five, then you're 50% fatigued. And if they go from ten to two, you're 80% fatigued. And it's a more advanced form of program modification. But generally, you can use it as an indication of whether to increase volume because, if I have a client and their repetitions go 10/10, 9/9 and they are giving high effort, then that's an indication for me, okay, there's evidently not much neuromuscular fatigue. So we can experiment potentially with higher training volumes. If someone's repetitions go like 10/5/2, then I think there's not much point in adding another set because they're already at two repetitions. They would have to decrease the weight. And there's evidently already a whole lot of neuromuscular fatigue. So maybe I would actually experiment with taking off the last set and see if they may not improve more because of better recovery.

SPENCER: I've heard some people claim that there can be a distinction between having big muscles and having strong muscles, and that some people do exercises to make their muscles big, but it doesn't necessarily make them super strong. What is the real trade-off there?

MENNO: It's true, there is a big difference, especially in the short term between strength and muscle size. In the long term, the correlation is generally quite strong, especially if you're at maximal strength. For the power lifters, the correlation is nearly one to one. We're literally talking about 0.9 or higher correlations often, which is funny because, if you think about this, and you do go to a powerlifter competition, you can actually just get people to do a body composition scan, like a DEXA scanner, and the rank order would be virtually identical to the actual competition. So you could essentially say, “Well, we could just forgo the competition, and then we just measure muscle mass and we'll know who wins.” If you train for maximal strength with low volumes, you can develop a lot of strength for your neural mechanisms. So basically, the brain and nervous system become more efficient to perform that movement. And you can gain a lot of strength that way, without actually building a lot of muscle. On the flip side, if you do very high repetitions, and you do a lot of generalized training, you can make your muscles a lot bigger, but they won't develop that specific strength in those exercises. For example, if you don't do the power lifts, the squat, the benchpress and the deadlift, then you're probably not going to be very strong at them. But you can build a lot of muscle and you can get as big as you want, even though they're not mandatory exercises from a bodybuilding perspective. So there can be a big discrepancy if you train a certain way, but on average for people, strength and size correlate very significantly. And at the high level, they correlate extremely strongly. But there is a big difference because strength is essentially the sum of your muscle size, multiplied by the efficiency of the nervous system in controlling that muscle.

SPENCER: I see. Wait, so you said that doing high repetitions is how someone can build a lot of bulk without a lot of strength?

MENNO: Yep.

SPENCER: I see. So actually, lower repetitions would be for someone who just cares about the strength, not about the bulk?

MENNO: Yep, so powerlifters and Olympic weightlifters commonly trained with like one to five repetitions per set — they're tested lifts — and bodybuilders typically do eight plus.

SPENCER: So this is a bit more of a personal question. You're really, really strong, and people can tell when they look at you. They're like, “Okay, that guy, he's strong.” I'm wondering, how does this change the way people react to you? Do you notice people reacting differently? And I know, over your life, you haven't always been at the equal level of fitness, so you've probably seen some variation there.

MENNO: Oh, yes, definitely. There is a difference. It can be hard to tell because it occurs gradually. But my fiance has also said it, in terms of the attention she gets from guys. For example, when they're with me, they're more reluctant, or even they literally ask, “Is that your boyfriend?” And in the gym as well, I notice that, if you ask for a certain piece of equipment, even if you're very polite and nice, if you're way bigger than the other person, then they're like, “Oh, yeah, go ahead.” It's a very primal sort of dominant sign. Overall, I think it's positive, but sometimes you do evoke more fear. In business settings, I found it was slightly negative. There was this connotation of the jacked guy being dumber, meathead and everything. And I know from friends who used to work in France, they literally told him, “You definitely can't show your muscles. You have to cover that up. Wear dress shirts, because you look like a cartoon, dude.”

SPENCER: That's really interesting. Have you noticed a big difference in how women react around you?

MENNO: Women don't show it nearly as much, I think, in most cultures. I would say so but it's not nearly as much. The effect is much stronger on men than on women. And I think actually, there's also research showing that men typically overestimate the extent to which muscularity matters for attractiveness towards women. And women conversely, overestimate the extent to which being lean matters for men. In other words, as long as you look kind of strong and healthy, then that's most important for women, as a guy. And as a woman, you actually want to look healthy and fertile, and somewhat curvy, not extremely curvy, but you want to have some curves and a good waist-to-hip ratio. And you actually don't need to be like ‘Victoria's Secret-ly' for most guys.

SPENCER: So guys out there, you can get jacked to impress the other guys, but it doesn't impress the ladies quite as much. How much time per week do you have to exercise in order to maintain your level of fitness?

MENNO: Well, maintenance is very easy. I'm striving to keep growing, even if that's marginal improvements, but I could maintain two very intensive good 60- to 90-minute workouts per week.

SPENCER: And that's really amazing, that you can maintain that with so little time.

MENNO: Yeah, for performance level, you need a third or less of the volume needed to obtain a certain level of muscularity and strength to maintain.

SPENCER: I see, but to push to the next level, then you're gonna have to work just much, much harder, right?

MENNO: Right. If you were at maintenance, basically, you're gonna have to triple your volume.

SPENCER: Alright, final question for you before we wrap up. Let's say someone hates exercising. What do you think the minimum amount of exercise someone can do to get benefits is? Is it walking a few times a week? Is that going to do anything? Or is there a certain kind of bare minimum people should be shooting for?

MENNO: It's those response. The more you do, the better, up to a certain point. And the biggest benefits you get are from the first (say) three sessions per week. Most benefit from the first. High intensity generally has a much more time-efficient effect. There's research showing that, for example, even a single bike ergometer sprint — if you have one of those ergometer bikes in your house, for example — just one sprint to failure, basically every day, 30 seconds or one minute, you can actually already achieve very significant health benefits. And if you go to the gym three times per week, most people...well, they'd be long sessions, but you can have a very decent (when I say ‘decent,' even by bodybuilding standards) physique with three workouts per week. It's easier with six times; you'll get there faster, for sure. But you know, the big picture for most people, I think three hours per week, you can have very good results if you're efficient and smart about it, and you train hard.

SPENCER: Menno, thanks so much for coming on. This was super interesting.

MENNO: My pleasure.

[outro]

JOSH: How were you first introduced to the rationalist community or the EA community or some other adjacent community?

SPENCER: It's a funny story, actually. I run a meet-up group in New York called Ergo, and we put on social experiments. We have a rule that no two of our events are ever allowed to use the same format. So every event has to be in a new format. And we try to do events that teach people something but experientially, where you're actually doing something. And so I was doing an event (this was many years ago) and we had a speaker for that event — it was actually about artificial intelligence — and at the end of the event, the speaker said, “Hey, do you know about this group, LessWrong?” And I was like, “No, what's LessWrong? I don't know.” And so then he says, “Oh, well, they're actually having a meet-up tonight. Why don't I take you?” So he took me over. And that was the first time I'd ever heard of LessWrong or the rationalist community, and I met a bunch of New York rationalists. I mean, this was many, many years ago. And yes, that's how I heard about it. And then I started reading LessWrong the blog and meeting a bunch of people in that community and yeah, obviously, I have much in common with the way that rationalists think. And I think many people will think of me as a rationalist, although I don't think I'm really central to that community, but obviously I have a lot in common in terms of the way I value thinking clearly and trying to figure out how to make your mind better and trying to think probabilistically and understanding as well as you can.