Sam Bankman Fried was a profoundly poor decision maker, but he said one thing that I keep seeing more and more evidence for:
"I don’t want to say no book is ever worth reading, but I actually do believe something pretty close to that. … If you wrote a book, you f---ed up, and it should have been a six-paragraph blog post."
The more I read, especially non-fiction, the more I realize most most books are filler and once you understand the thesis you should stop before wasting any more time. Books also make it very difficult to have a conversation because you really can't reference them, and can't simply say "read this book, it explains everything" because no one is going to do that.
So anyway I'd like to thank you for reading this so I don't have to, and pointing to the actual science and evidence.
Yea I agree. I often end up skimming lightly if I think a chapter isn't worth reading, but sometimes you miss stuff that way. So this one I mostly read entirely through.
I do think there is some place for longer form, be it book or a blog post series like the molds' A Chemical Hunger. Some things you just need to set up longer than a single blog post, and staying immersed in a topic helps move you on some lower, sub-conscious level.
I think Burn did this for me with regards to CO. I always knew that I couldn't lose weight working out, but I would've shrugged if you asked me if it had increased my burn rate. Now, I'm quite confident it didn't increase my burn rate.
Yeah, Fried was a disgusting little troll and somehow managed to be wrong about even things that were handed him half-right to begin with. The overwhelming majority of books should have been blog posts, but that doesn't indicate that all books should be. Even though there has been little agreement about which books are worthwhile, everyone for the whole history of literacy has known that they weren't all good.
The problem is that everything burns calories, including not burning calories. Being too big burns calories. Eating more burns calories. Drinking coffee burns calories. Drinking a frapp from starbies burns calories. Going in the sauna burns calories. Cold plunging burns calories. Shitting yourself and falling down the stairs burns calories.
The question isn't "does this burn calories?" - if it were, the meme version of Ray Peat would be right and no functional limit on daily orange juice intake would apply. Drink more, lose more.
The question, instead, is "what effects does this have on the rest of the system, which if you' re reading this probably has dozens of broken homeostatic mechanisms?"
So, for instance, an example beloved of this blog would be "eating whipped cream burns calories". This is true in the short term (in the same way that drinking orange juice is), but is also (apparently) true in the long term -- many good things happen downstream from the cream (that rhymes, a motto waiting to happen; say it in Macho Man Randy Savage's voice and see for yourself). Insulin sensitivity, uncoupling, satiety, lipolysis, whatever - - they're all downstream from the cream, brother.
So let's do exercise now. Pontzer in the book says that one of the things that westerners' bodies are doing with the energy they aren't burning walking around all day is 'inflammatory processes'. These are known to decrease insulin sensitivity. They're also known to be decreased by exercise (in mice and in men). Every single study showing the uselessness of exercise for fat people starts with folks packed fulla PUFA, and forces them to try to empty out their ocean of inflammation with a little pail. Now, if I said insulin sensitivity 'burns calories' when it's downstream from the cream, why not when it's wise with the 'cize? If inflammation (and the resulting diabetes) go down, what's going to happen to obesity? Well, nothing if a person keeps eating all the poison that made him fat in the first place. Can't outrun a bad diet. But in a low-carb healthy-fat context, the exercise is going to be involved in making changes that result in fat loss. That's calories no longer stored in the body, not because they were 'burned' while on the treadmill, but because of downstream effects. Unless, of course, we're claiming all these downstream effects are only good when caused by cream, not by exercise.
Run a crossover on ad-lib high-fat low-protein keto, with 'hours of zone two cardio daily' as the experimental arm, and something good will happen. Hell, it might break through your summer plateau with no other changes needed.
Largely agreed; the "bucket of carolies" model of obesity just has a hard time explaining pretty much anything at this point. The body is a complex system, and we've known that for 100+ years. You can't just add 1 thing and expect that to have 0 downstream second order effects.
It could be that exercise "works" once you're unPUFA'd and that might explain the variance. But then wouldn't the (presumably unPUFA'd, and never-PUFA'd) Hadza burn way more carolies than us poor PUFA'd fucks? They walk miles a day!
As a personal testimonial (us cool kids on the internet call this n = 1), ex150 does absolutely fuckall for me other than make me tired on weeks where I'm not getting a ton of zone two cardio. Over the last two months I accidentally did two crossovers of testing this back to back, and the same thing happened both times. Ex150 + zone two = energy, clarity, weight loss, and purple test strips. Ex150 without exercise = exhaustion, fog, weight plateau, and pink test strips, even when I EAT MOAR on the exercise weeks.
I suspect there's some large and somewhat complex bucketing/rate limiting stuff going on in our big ol' bucket of carolies.
Just like you can't outrun a bad diet, you can't out-eat infinite caloric burn in the muscles. That's what Ponzer says in the book, that we have a limit of how many carolies can be used in the furnace on any given day (around 5-6,000kcal/day he said, or about 2.5-3x your BMR).
That's why I suspect that even if you eat infinite crabs, if you run enough ultramarathons, you'll still get into ketosis. At some point it's not about balance any more, you need to consider your "cash flow" or whatever, the flux of different substrates. And to be the cream (mmm) of the crop, you need to be using them all.
This is pretty obvious in the shorter term with workouts. If you do CrossFit, you'll very quickly reach your "bonking" limit on metcon workouts, when your muscles run out of ATP and you go into that secondary, slower mode. Clearly we can't sprint forever, that substrate buffer is being used up after a few seconds and you need to switch to a secondary system that has more endurance, but less horsepower.
Something like this probably happens all the time with every substrate in the body, and averaging it all out into CAROLIES makes you blind to these effects.
E.g. the "elite athletes do burn more" effect could be explained that way: the substrate pathway from "food intake -> muscles" isn't enough to power the extreme demand, but you can still use substrate from the adipose flux pathway. An elite athlete would, pretty much by definition, make use of ALL the available pathways.
So basically CICO works if you out-exercise your intake flux and force your body to get to fat flux lol? But all of this is predicated on actually being able to use your fat flux, which doesn't seem to be the case in most metabolically unhealthy people to begin with..
Probably still means you need to 1. fix your metabolic issue enough, 2. then you can exercise, 3. then you need to work up a volume high enough that the body can't simply cover it from food intake by increasing your hunger.
The elite athlete (or really any athlete - it's a smooth curve) has widened the bandwidth of some chosen pathways. This, along with our weird bipedal running/hunting is why we can grind along in zone two, tracking a zebra whose terrified sprints grow slower and more labored every time we come trotting into view.
To be clear, I probably have a lower opinion of CICO than you do, having spent more years trying to literally outrun a bad diet. CICO doesn't work because a PUFAtality in the making will just want to eat more as a result of exercising. Part of that is physical pain making us need that endocannabinoid hit, part is ECS activation from burning our stored PUFAs during exercise, some of it is deranged ghrelin, broken homeostats, etc. But part of it is poor conditioning -- every time I see a fat person working out, it is readily visible that he is in zone three at least. From personal experience, it's zone three that makes me ravenous. It's zone three that made me go from 80 minutes on a stairclimber to directly walking down the stairs into a Krispie Kreme to eat more calories than the machine's readout had claimed I'd burned. Zone two? Most PUFAers have no zone two -- they go right from sedentary to the 'this will make me ravenous' zone, exacerbating at least one of the pathways that drive the CI portion. I just now came back from biking 20 miles in a breezy zone two, and am not even slightly hungry (it took me the first 10 miles to recover from dinner: fatty beef ribs). This "how hungry will it make me" factor isn't addressed in the literature on weight loss and/or cardio, at least not that I've seen.
To recap, my contention is that Z2C can help a person access the benefits of a HFLCLP diet, which can over time reverse the lion's share (pun intended) of metabolic PUFActors. My stretch-goal contention (not addressed here yet) is that the reason this even works for humans is because we're metabolically built for this kind of training, even if our morphology has changed a lot in the last 3,000 years. A man shaped like you are on the outside has the same(ish) mitochondria as his 100x great-grandfather, but his different body shape means he's built for hours of zone two doing things like lifting rocks onto the walls of sheep-pens or working iron on an anvil, not chasing zebra. But deep down inside, the powerhouses-of-the-cell can enjoy an analogous kind of health in either activity. Other primates seem much more optimized for zone one, and something like a cheetah is only ever in zones one and five. But it's not a random freak of some tribes in africa that they can run animals literally to death, and what's going on for them under the hood isn't much different than what was going on for that massive Swede in the Jack London story who could break trail before a sled-dog team in waist-deep snow for 12 hours with only a couple short breaks to eat dried fish. And these men, so many thousands of miles and thousands of generations apart had likely similar heartrates and fuel-preferences in these very different feats of metabolic strength.
Great comment, thoroughly enjoyed reading it and this whole CO thing not 'utilising' vs. burning additional nutrients (fat stores) seems far fetched. That would be like saying the elite athletes are just increasing their energy distribution to more inflammatory or other metabolic pathways to counteract the additional strain put on the body system by the exercise...
The zones of training make more sense, as anyone with weight will attest, their heartrate is naturally higher and jumps higher via movement than a similar person with less adiposity.
Additionally at higher lactate levels there seems to be compensatory increases in cortisol and adrenaline that while conflicting to weight loss, make perfect sense to maintaining body fat in the moment/directly after.
Also just a nitpick or pet peeve of my own, but people drinking Deuterium via DLW is a big no no and you're asking for down regulation of metabolism through destruction of your mitochondria from the deuterium molecules suddenly being vastly increased in a system that is shown to not like being anywhere above even ~135ppm.
Especially when the amount in our bodies Is equivalent to 5g of heavy water, and these guys are drinking how much???
you mention an upper limit of 5-6,000kcal/day: are there known limits on the body's ability to take in carolies from the gut? Maybe varying by protein/fat/carbs, but I could believe that if I take in (say) 10k cals of fat in 24 hours, my body is only going to absorb some maximum amount of that, based on digestive limits, with the rest being (literally) flushed away.
That's pretty much what Pontzer is saying in the book, that it's a digestive limit. But that seems mostly backed by "even the highest TDEE numbers we've ever measured aren't higher than 2.5-3x BMR" not some mechanistic explanation of the limits of the digestive system. So maybe you could figure out some way to optimize that and become an olympian :) Not sure.
Maybe if you don't explicitly support CICO orthodoxy in your book, it simply won't be published.
I just can't understand how else someone can envision, conduct, evaluate and write about studies showing that mammalian bodies are able to precisely adjust their calorie expenditure to maintain their weight, and then say you need to eat less.
Obviously, according to HIS OWN RESEARCH WHICH HE JUST SPENT A BOOK DISCUSSING, if you eat less, your body will simply lower its metabolism.
It would be like Galileo presenting his calculations showing the planetary orbits in a heliocentric system, predicting their motions elegantly and simply, and then concluding, "of course, the Earth is the centre of the universe"
It's mostly unintentional motte-and-bailey caused by specialization. Academics (and Pontzer certainly is one) defer to orthodoxy whenever they stray to the edges of their particular spotlights. This is a healthy instinct, and the ones who do otherwise honestly are worse - that's how we get 'doctors' pontificating on YouTube about things of which they are totally ignorant.
[but this shades into what I wanted to say, which I'll make its own top-line comment)]
I'm not sure how to square these results with my experience. I went from almost 30 BMI to under 22 BMI using running extensively. Of course, there are always a lot of confounders, but on my weight loss plot, you can basically see the periods where I was running consistently (with the exception of the potato diet, I was not running during that yet still lost weight). If it's not CO, then it must decrease appetite and hence CI, I guess, which does seem possible based on my experience. Nevertheless, I would not discount running even low mileage (I'm running around 30 miles weekly, occasionally high intensity) as a weight loss strategy.
It seems to have worked for my 1 friend whom I mention in the article, too. He also ran at least 30 miles a week, whereas the studies Pontzer cites seem to be a bit less than that (I think up to 25mi?)
Could be that you got over that "hump" into the "it actually works" zone, or maybe you're just a good responder to exercise, or the CI decrease you mention.. who knows. I always just get hungrier from exercise :)
I read *Burn* 13 months ago and basically got the same message from it as you did. I really appreciated learning about the constrained model of energy balance and having it hammered home.
On the negative side (in addition to what you posted), the last chapter contains some really bad economics, for example claiming that all fossil fuels will be consumed in 50 years. (Making this claim is ironically as bad economically as arguing for the additive energy expenditure model is physiologically.) There was also a dose of Kendi-esque "anti-racism" mixed in throughout the book, but I assume that's because the book was published in 2021 and I suspect publishers were really pushing that narrative at that time. (I read a number of books published in 2021-2022 that all seemed to gratuitously throw in this "anti-racism" angle wherever possible. I don't think it was all on the authors, but it could have been the authors' doing in many instances. It's ultimately nearly impossible to sort out because most of these authors haven't published similar books pre- or post-2021.)
Some stuff I found interesting and worthwhile that you didn't cover in your blog post:
• His discussion of pregnancy and breastfeeding being as grueling as cycling the Tour de France gave me a new appreciation for women, and humans' general ability to reproduce.
• No matter the circumstances, the body cannot absorb more than (2.5 x BMR) kcal (≈4,000-5,000 kcal) ... and that Phelps is truly an outlier not in terms of his swimming ability but in terms of his metabolism (as you pointed out)
• When apes are put in captivity (or in conditions where they would gain weight), they gain tons of lean mass, whereas humans gain lots of fat. Peter Attia in *Outlive* points out that this is because apes have an enzyme called uricase which basically makes them unable to convert fructose into fat. My reading of all of this is that this is why apes generally don't live in cold weather environments (Japanese macaques excepted). The implication for this is that if humans had uricase, a BMI of 35 would mean people would look like NFL defensive linemen instead of sumo wrestlers.
Haha inb4 gene therapy... certainly some people are trying to work on stuff like this. I find it very scary because I think it's much easier to do crazy harm than to fix anything useful. The body is an extremely complex and fickle system, and so far, messing with singular points has pretty much gone wrong most of the time.
Agreed on the fossil fuel stuff - Pontzer must not've heard that peak oil is over and we have fracking now :D And yea also the woke stuff. Like pointing out that all that metabolic research was done by WHITE MEN. Says the white man man with the whitest name alive^^ How is that relevant to the research?!
Interestingly as he shows about Phelps, even Phelps isn't that crazy an outlier - he's at 3x instead of 2.5x. He's just a giant man with a lot of lean mass, so of course his BMR is much higher than that of most people.
> On the negative side (in addition to what you posted), the last chapter contains some really bad economics, for example claiming that all fossil fuels will be consumed in 50 years. (Making this claim is ironically as bad economically as arguing for the additive energy expenditure model is physiologically.)
I think I remember they said that 50 years ago as well. Luckily, fusion energy is just 50 years away.
Thank you for the review. As I mentioned, I have a more charitable take on Pontzer's book due to my n=1 lived experience with weight loss.
My read on the calorie discussion in this book is that humans in general have a fairly narrow band of energy expenditure, unless you exercise A LOT.
You convert food into energy, and as long as inputs are within that narrow band, your weight will eventually get to where it needs to be. That has been my experience, with a long (4 years), slow and steady down-path until things just stabilized. Silly MFP app tells me that when I exercise I can "add" 500 cals... that is not how it works for me. I need 1,900 calories (on a 3-day average in my experience) in food inputs to maintain my current weight. I do HIIT for 60 minutes x 5 per week, and it has zero bearing on the 1,900 cals.
IMHO, Doctors should stop saying "eat less, move more" and instead say "eat more whole foods minimally processed until you feel full. Exercise to help your body move better and build resiliency".
Pontzer does not answer the What (highly processed foods? PUFAs? Microplastics? Added sugars?) is causing a disconnect between satiety mechanisms and food ingested. My theory is that the satiety pathway has been broken in modern times. People stop eating when they feel full, little kids are great for that. But we seem not to get that clue anymore, or to bypass it. Food abundance does not cut it.
I am an Occam's Razor type of nerd. The constrained calorie model seem proven by the research, the fact that energy expenditure is within a narrow band to me is proven as well (exercise is fantastic for many well documented reasons, from mental acuity to chronic disease prevention), so my lesson from the book is that you need to find where your equilibrium is calorie-wise, and stick to that forever and sustainably. It may be beef and cream, or it may be fibrous veggies, or whatever rocks your boat.
On satiety (and outside the book's remit) I have found that avoiding highly processed items changed my feelings of fullness for the better.
The fact that CICO is a tautology does not make it false. I can say "today it will either rain, or not rain" and the statement will be true, but it does not explain anything beyond itself. The question we are all trying to answer is what may cause the rain, or what may cause not to rain. There are so many confounding factors (chemicals, highly processed food, thermal effect of food, etc) that picking one culprit may be impossible. But stick to your very narrow calorie band, and you shall succeed over a long period of time. Slow and steady wins the race.
Whoever wants to try my approach, DM me (I think that is possible). Thank you again, it is great to have a forum to discuss stuff like this.
> Doctors should stop saying "eat less, move more" and instead say "eat more whole foods minimally processed until you feel full
I agree with this. That's why I think it's silly to focus on "calories." If you don't remove the processed foods (and what's bad about them, wouldn't that be interesting? It's not the drying and chopping up and canning, I assume), reducing overall calories won't do much for most people. You'll just make yourself more hungry.
So "is it fruit or is it beef or is it heavy cream" is kinda the whole game. If you're just brushing that under the carpet because "they all just calories" then you've missed the entire question.
> The fact that CICO is a tautology does not make it false. I can say "today it will either rain, or not rain" and the statement will be true, but it does not explain anything beyond itself.
Exactly my point. Tautologies are true, by definition - it's just that they don't tell you anything about how to achieve fat loss.
The dishonest thing CICOpaths do is they say "CICO is always true and therefor eat less move more works." But that doesn't follow at all from CICO.
I kinda don't believe in "slow and steady." Slow and steady implies that we have a choice of how fast to go. I have yet to see anyone really have that option.
Most people don't lose anything ever. A few people lose very slowly. A few people sometimes lose very quickly. I lost 20lbs the first month on ex150, and 10lbs each the next few months. It was spectacular. Of course, it's slowed since and now I have many plateaus.
But do I think there would've been any benefit to going slower? Not at all. What would be the upside? I lost no lean mass, I have no excess skin... why weight artificially?
On the other hand, I also don't believe we have a way to "go faster" if we're honest about the goal. Yea, we can starve ourselves a little bit until our willpower runs out or our metabolism is suppressed. But as we see with many anecdotes and studies, that stuff tends to rebound, and even worse, if you actually HAVE the willpower it'll wreck your metabolism, possibly long-term.
No thanks on that front.
I like focusing on the "what's the root cause of this whole malaise" part. What's causing our fuel partitioning system to malfunction? What's causing us to divert "calories" to fat when we don't need to store any fat, and thus taking them away from our furnace, reducing our CO, and increasing our CI via hunger?
To me it always feels like we "just" have to identify the blockage, the sand in the gears, and clean it out. If we fix that, the "everything will fall into place over time" thing you mention is true.
That's what it's been for me twice now. I found some magic diet, and I just magically lost tons of weight eating ad-lib doing pretty much no exercise.
Unfortunately no; Pontzer's work seems to focus exclusively on the CO side of CICO. At least in this book. The only diet things was the Biggest Loser and similar, where he briefly mentions that caloric restriction will downregulate your metabolism.
Interesting review, but a bit too harsh by claiming several times that exercise doesn’t burn calories at all. That’s just not true and could mislead people. Pontzer’s theory is that more exercise doesn’t lead to a PROPORTIONAL increase in calories burned, and I don’t think your post makes this clear enough, even though you’re pretty nit-picky about Pontzer.
In my own weight-loss experiments, I also found CICO to be unreliable, but it certainly does have some truth to it, with a few hidden catches. So far I’ve looked into things like tracking errors, constrained TEE, and the role of the microbiome, but practically speaking those have mostly been dead ends so far. I found that correctly tracking CI and CO is very hard and actually impossible to do, that my long fasting experiments might have increased my hunger by altering my microbiome and why crazy workout days at the gym + long cardio sessions all in the same day don't work.
However, I did manage to make CICO work for me eventually by tweaking my numbers—upping my tracked intake by 20% and lowering my tracked output by 20%. This tweak shows the nuances in energy balance that Pontzer talks about. Plus, it acknowledges that we all fudge the numbers a bit and our memories aren’t perfect. Of course thats only the theory, as I am not in 100% integrity following through with my CICO plans... but it's at least something.
Anyway, I like your site and your experiments. Keep up the work.
Thanks! I quoted Pontzer a lot saying the exact thing he says, so I'm hoping I got his opinion across correctly :) But yea technically what you're saying is true. Even the constrained model graph I show has the TDEE going up a little bit in the beginning. And we could probably make it go up at the very end, as you get into Michael Phelps levels of activity.
The issue I have with "playing around with my CICO until it worked" is; you don't actually know that the CICO is what made it work. Maybe it was something else you weren't even thinking of?
:) You certainly did quote him but you also make bold unsupported claims (like in the title), which is what I was getting at. Nutrition science remains a mystery. But my adjusted CICO is the best model I currently have 🤷♂️ so its valuable to me. Even if it’s just right for me by coincidence.
I don't feel like you've quite got the point, which is that you can't really track CO without doing something like double labeled water, in which case you'll find that if you up your expenditure by running a bunch, your body will take that from other things, keeping your total CO constant.
> you can't really track CO without doing something like double labeled water
I think that statement is wrong. You can't track it precisely but that isn't what we need anyway. To lose weight we would only need to know that we are roughly in a deficit most of the time.
> if you up your expenditure by running a bunch, your body will take that from other things, keeping your total CO constant
That, again, I think is wrong. That's not Pontzer's theory. He challenges the traditional models of energy expenditure, which assume a direct and proportional increase in calorie burn with increased physical activity, and says they are overly simplistic. Instead, he suggests that while physical activity does increase total energy expenditure, the increase is not linear. BEYOND A CERTAIN POINT, the body compensates for higher activity levels by reducing energy spent on other physiological processes. The thing is, that the level of TEE above which the additional CO plateau is quite high: from what I understand, between 2500-3000. That means below that you can expect that more CO actually means more CO. And at least in my case I rarely go over 3000kcal in a day, so unfortunately his theory does not really apply to my situation that often...
That "fine tuning" method assumes naive CICO is true; though. Which Pontzer mostly disproves here. And we can't test it without ACTUALLY measuring our CI and CO, both of which are largely impossible (unless you do CO w/ DLW).
The point when the body starts compensating is pretty low, though. As Pontzer demonstrates, the Hadza walk 15k steps a day and still have the exact same TDEEs as lazy Americans. So unless you're crossing the boundary from Wal-Mart sedentary to normal, or from normal to Michael Phelps, you're unlikely to see any significant change.
I guess I'm confused by how you think you can measure TEE without double labeled water or similarly advanced technique?
And also I'm confused by how you square your statement with the quoted sections in the OP saying the Hadza of Tanzania having the same CO as sedentary people in a bunch of western countries. It seems to me that if you live a normal western life where you walk to and from your car and do occasional chores around the house, you do actually have the same TEE as the Hadza.
For anyone coming to this post 2+ months late, the YouTube channel "Kurzgesagt" recently did a 12-min video summarizing Pontzer's body of work. https://www.youtube.com/watch?v=lPrjP4A_X4s
They did a good job summarizing everything and making it accessible to the lay person. I'm curious to see what they have to say about diet in their forthcoming video (not sure when it will drop), but definitely keep any eye out.
I had a 5 month period last year where I was running 55km / 5.5 hours per week. Almost all of this was low intensity, in my lower zone 2 heart rate range. I went from 76kg to 70kg in this time, and I was eating more than before. I didn't have any weird diet changes, or quit drinking, or have any major lifestyle changes. So if it's not calories out, what is causing me to steadily lose weight in this period? And how come I went back to maintaining weight when I stopped running and went back to eating the amount I ate before? Does getting lots of zone 1 / zone 2 kick your body into fat burning mode somehow? If the move more part of eat less move more is wrong, then I should have gained weight while running and lost weight after I stopped (or maintained in both, or maintained after I stopped running only).
55km/wk is about 35mi/wk. That's nearly 4x what they considered "high exercise" in one of the studies, and nearly 2x what they considered "very high exercise."
If you run that much, you're probably in the top 1% of the population for miles run/cardio?
Pontzer says in the book that at some extreme levels, it seems to increase CO again. Just not for the vast majority of people in the vast majority of ranges.
I was in the top 1% of Garmin users for running distance and time in my age group. But I think it's hard to argue that less than an hour a day is an extreme amount of exercise, you'd do about the same on a three day a week gym program, and casual cyclists would probably consider this a pretty moderate volume. Compared to the Hadza, this volume is tiny. You also have to consider that the equivalent intensity for someone who's unfit would be a brisk walk or uphill walk, rather than 6min/km.
What I see claimed a lot is that high volume low intensity cardio trains your body's ability to use fat for energy. See for example this post about an actually extreme version of this where someone trained 20-25hrs/week: https://alancouzens.com/blog/improving_fat_burning2.html
They were running an hour a day, 4 days a week in one of the trials. And that had pretty much zero effect.
So you could argue that it needs to be even more than that, and then you'll see SOME effect or even big one... but I'm not sure I believe that to be true for most people.
It might just be that a small % of people are hyper responders to exercise to begin with, and "long bouts of exercise w/ no benefits and lots of downsides" filters out everyone else.
And even the Hadza don't burn more calories than sedentary Americans, so why bother emulating their exercise routine?
My understanding is that *low intensity* cardio (zone 1/2) trains the fat-burning systems to be more efficient - so that you can burn more fat per hour. This seems kind of useful if you want to lose fat (weight). But it's important that it's low intensity, you're supposed to feel fresh at the end of it, not knackered.
The study you mention maybe(?) had people working *hard* for 1 hour, 4 days a week - that's a different thing entirely. Creates a stress on the body that needs recovery, and the energy source would be more glycogen and less fat so it doesn't train fat-burning systems in the same way.
Yea these people were trying to "burn carolies to lose fat" not to train their fat burning systems. I do enjoy going for walks, so I wonder if this goes very well with being keto adapted; if both are very amenable to fat burning. I'd call my walks invigorating, when I return, I feel fresher than when I left. Pretty much no exertion unless there happens to be a hill. Is that zone 1?
Yeah, that's it, definitely goes well with low carb / keto. 👍
Harder walks with faster pace / stairs / longer times / rucking / etc are probably zone 2 if the effort level is not too high. Exact definitions vary and are non-trivial to test for, but that's close enough. I just go by how long I could maintain that amount of effort for. If it's "I could go hiking at this effort level all day" it's zone 2, if it's "I'm burned out and need to rest after an hour" then it's zone 3 (or higher).
I think part of the problem with books like this is that publishers will try to get the author to make prescriptions after describing a problem, which forces them out of their area of expertise. Marx got some stuff right about capitalism but his proposed solution lead to misery and death on a huge scale.
More interesting would be the question if exercise doesn't increase the "CO" part what does? Same goes for changing the CI part of the equation how does it impact CO?
I think that there isn't one blanked thing that always make CO go up w/o context.
Both CI (via hunger) and CO (via "feeling energized" and NEAT and BMR and so on) are normally pretty tightly regulated by the body.
I think that you can "vastly increase" your CO with "this one little trick" but only if your metabolism is currently broken, and the regulator isn't working as intended. I.e. if you've been starving yourself and your metabolism is vastly depressed, like with the biggest loser people. Just eating more will vastly increase your CO. I think that's not controversial, it's just that in most people it'll lead to regaining all the fat they just starved off. (I think ex150 type diets could be a nifty trick to avoid the regain here!)
I also think that if you're eating a "normal" amount and have say a TDEE of 3,200kcal/day, and then you stuff yourself to the brim with more extra food, your CO would likely go up a bit to maybe 3,300-3,500. Maybe even higher. Anecdotally there are keto people who've eaten 4,000kcal/day for a period without gaining any fat. I've done it myself, twice, for about a month each.
But there's a limit as Pontzer shows, I doubt that you can get your TDEE to 10k via overfeeding. Maybe not even 5k.
Another factor is that we think PUFAs decrease your CO, and increase your CI by sneakily channeling a % of all your CI into adipose tissue no matter what (incorrect "fuel partitioning").
So stopping PUFA consumption, and depleting yourself of PUFAs, would over time correct the regulatory mechanism and thereby (positively, hopefully) manipulate your CI and CO.
Just acutely, PUFAs trigger the endocannabinoid system, which makes your CI go up by increasing your hedonic appetite. Cutting out the PUFAs will likely decrease spontaneous CI.
Basically it's context all the way down, and it's all marginal :)
Now I'm interested in what that actual calorie out from activity curve looks like. Probably like the tangent curve or something? Where are the actual inflection points, and how does genetics impact those?
I suppose you'd have to run DLW on the same individual over and over, every 500kcal of (hypothetical) exercise added or so, and graph that? I think it's still way too much work/too expensive for that.
I’m not sold on the methodology. An unchanged ratio 2H/18O can mean that nothing has been burned, OR that a lot of calories has been burned, but that almost all O of CO2 comes from O2 from respiration ?
In other words, it looks like to me this methodology can’t distinguish between "more exercise don't burn calories" and "more exercise burn calories, but H2O mostly stays H2O, O2 in breathed out CO2 mostly come from breathed in O2". Or am I missing something obvious ?
Hm wouldn't a lot of O2 coming in through respiration be happening anyway? Unless you somehow managed to only burn the O from incoming O2 and not the one from the water.. I guess I don't really know how these pathways work exactly, e.g. if there are separate "pools" or "streams" or what not. Above my pay grade I guess :)
This is great. I quite liked the book for the CO findings and the use of DLW was interesting. I did read previous reviews before buying that it wasn’t a weight loss’ book & as you say it doesn’t offer any real solutions. I like how you highlight the cocky arrogance of Pontzer and that of the others who all cozy up in their elite circles of smugness. However IMO, without doubt, this is important work and can’t be ignored.
Yea agreed. Glad I wasn't the only one feeling like he was a bit cocky for essentially not having any answer either. I'm all for disproving things, but then we shouldn't shit on people trying new solutions.
Sam Bankman Fried was a profoundly poor decision maker, but he said one thing that I keep seeing more and more evidence for:
"I don’t want to say no book is ever worth reading, but I actually do believe something pretty close to that. … If you wrote a book, you f---ed up, and it should have been a six-paragraph blog post."
The more I read, especially non-fiction, the more I realize most most books are filler and once you understand the thesis you should stop before wasting any more time. Books also make it very difficult to have a conversation because you really can't reference them, and can't simply say "read this book, it explains everything" because no one is going to do that.
So anyway I'd like to thank you for reading this so I don't have to, and pointing to the actual science and evidence.
Yea I agree. I often end up skimming lightly if I think a chapter isn't worth reading, but sometimes you miss stuff that way. So this one I mostly read entirely through.
I do think there is some place for longer form, be it book or a blog post series like the molds' A Chemical Hunger. Some things you just need to set up longer than a single blog post, and staying immersed in a topic helps move you on some lower, sub-conscious level.
I think Burn did this for me with regards to CO. I always knew that I couldn't lose weight working out, but I would've shrugged if you asked me if it had increased my burn rate. Now, I'm quite confident it didn't increase my burn rate.
Yeah, Fried was a disgusting little troll and somehow managed to be wrong about even things that were handed him half-right to begin with. The overwhelming majority of books should have been blog posts, but that doesn't indicate that all books should be. Even though there has been little agreement about which books are worthwhile, everyone for the whole history of literacy has known that they weren't all good.
The problem is that everything burns calories, including not burning calories. Being too big burns calories. Eating more burns calories. Drinking coffee burns calories. Drinking a frapp from starbies burns calories. Going in the sauna burns calories. Cold plunging burns calories. Shitting yourself and falling down the stairs burns calories.
The question isn't "does this burn calories?" - if it were, the meme version of Ray Peat would be right and no functional limit on daily orange juice intake would apply. Drink more, lose more.
The question, instead, is "what effects does this have on the rest of the system, which if you' re reading this probably has dozens of broken homeostatic mechanisms?"
So, for instance, an example beloved of this blog would be "eating whipped cream burns calories". This is true in the short term (in the same way that drinking orange juice is), but is also (apparently) true in the long term -- many good things happen downstream from the cream (that rhymes, a motto waiting to happen; say it in Macho Man Randy Savage's voice and see for yourself). Insulin sensitivity, uncoupling, satiety, lipolysis, whatever - - they're all downstream from the cream, brother.
So let's do exercise now. Pontzer in the book says that one of the things that westerners' bodies are doing with the energy they aren't burning walking around all day is 'inflammatory processes'. These are known to decrease insulin sensitivity. They're also known to be decreased by exercise (in mice and in men). Every single study showing the uselessness of exercise for fat people starts with folks packed fulla PUFA, and forces them to try to empty out their ocean of inflammation with a little pail. Now, if I said insulin sensitivity 'burns calories' when it's downstream from the cream, why not when it's wise with the 'cize? If inflammation (and the resulting diabetes) go down, what's going to happen to obesity? Well, nothing if a person keeps eating all the poison that made him fat in the first place. Can't outrun a bad diet. But in a low-carb healthy-fat context, the exercise is going to be involved in making changes that result in fat loss. That's calories no longer stored in the body, not because they were 'burned' while on the treadmill, but because of downstream effects. Unless, of course, we're claiming all these downstream effects are only good when caused by cream, not by exercise.
Run a crossover on ad-lib high-fat low-protein keto, with 'hours of zone two cardio daily' as the experimental arm, and something good will happen. Hell, it might break through your summer plateau with no other changes needed.
Largely agreed; the "bucket of carolies" model of obesity just has a hard time explaining pretty much anything at this point. The body is a complex system, and we've known that for 100+ years. You can't just add 1 thing and expect that to have 0 downstream second order effects.
It could be that exercise "works" once you're unPUFA'd and that might explain the variance. But then wouldn't the (presumably unPUFA'd, and never-PUFA'd) Hadza burn way more carolies than us poor PUFA'd fucks? They walk miles a day!
As a personal testimonial (us cool kids on the internet call this n = 1), ex150 does absolutely fuckall for me other than make me tired on weeks where I'm not getting a ton of zone two cardio. Over the last two months I accidentally did two crossovers of testing this back to back, and the same thing happened both times. Ex150 + zone two = energy, clarity, weight loss, and purple test strips. Ex150 without exercise = exhaustion, fog, weight plateau, and pink test strips, even when I EAT MOAR on the exercise weeks.
I suspect there's some large and somewhat complex bucketing/rate limiting stuff going on in our big ol' bucket of carolies.
Just like you can't outrun a bad diet, you can't out-eat infinite caloric burn in the muscles. That's what Ponzer says in the book, that we have a limit of how many carolies can be used in the furnace on any given day (around 5-6,000kcal/day he said, or about 2.5-3x your BMR).
That's why I suspect that even if you eat infinite crabs, if you run enough ultramarathons, you'll still get into ketosis. At some point it's not about balance any more, you need to consider your "cash flow" or whatever, the flux of different substrates. And to be the cream (mmm) of the crop, you need to be using them all.
This is pretty obvious in the shorter term with workouts. If you do CrossFit, you'll very quickly reach your "bonking" limit on metcon workouts, when your muscles run out of ATP and you go into that secondary, slower mode. Clearly we can't sprint forever, that substrate buffer is being used up after a few seconds and you need to switch to a secondary system that has more endurance, but less horsepower.
Something like this probably happens all the time with every substrate in the body, and averaging it all out into CAROLIES makes you blind to these effects.
E.g. the "elite athletes do burn more" effect could be explained that way: the substrate pathway from "food intake -> muscles" isn't enough to power the extreme demand, but you can still use substrate from the adipose flux pathway. An elite athlete would, pretty much by definition, make use of ALL the available pathways.
So basically CICO works if you out-exercise your intake flux and force your body to get to fat flux lol? But all of this is predicated on actually being able to use your fat flux, which doesn't seem to be the case in most metabolically unhealthy people to begin with..
Probably still means you need to 1. fix your metabolic issue enough, 2. then you can exercise, 3. then you need to work up a volume high enough that the body can't simply cover it from food intake by increasing your hunger.
The elite athlete (or really any athlete - it's a smooth curve) has widened the bandwidth of some chosen pathways. This, along with our weird bipedal running/hunting is why we can grind along in zone two, tracking a zebra whose terrified sprints grow slower and more labored every time we come trotting into view.
To be clear, I probably have a lower opinion of CICO than you do, having spent more years trying to literally outrun a bad diet. CICO doesn't work because a PUFAtality in the making will just want to eat more as a result of exercising. Part of that is physical pain making us need that endocannabinoid hit, part is ECS activation from burning our stored PUFAs during exercise, some of it is deranged ghrelin, broken homeostats, etc. But part of it is poor conditioning -- every time I see a fat person working out, it is readily visible that he is in zone three at least. From personal experience, it's zone three that makes me ravenous. It's zone three that made me go from 80 minutes on a stairclimber to directly walking down the stairs into a Krispie Kreme to eat more calories than the machine's readout had claimed I'd burned. Zone two? Most PUFAers have no zone two -- they go right from sedentary to the 'this will make me ravenous' zone, exacerbating at least one of the pathways that drive the CI portion. I just now came back from biking 20 miles in a breezy zone two, and am not even slightly hungry (it took me the first 10 miles to recover from dinner: fatty beef ribs). This "how hungry will it make me" factor isn't addressed in the literature on weight loss and/or cardio, at least not that I've seen.
To recap, my contention is that Z2C can help a person access the benefits of a HFLCLP diet, which can over time reverse the lion's share (pun intended) of metabolic PUFActors. My stretch-goal contention (not addressed here yet) is that the reason this even works for humans is because we're metabolically built for this kind of training, even if our morphology has changed a lot in the last 3,000 years. A man shaped like you are on the outside has the same(ish) mitochondria as his 100x great-grandfather, but his different body shape means he's built for hours of zone two doing things like lifting rocks onto the walls of sheep-pens or working iron on an anvil, not chasing zebra. But deep down inside, the powerhouses-of-the-cell can enjoy an analogous kind of health in either activity. Other primates seem much more optimized for zone one, and something like a cheetah is only ever in zones one and five. But it's not a random freak of some tribes in africa that they can run animals literally to death, and what's going on for them under the hood isn't much different than what was going on for that massive Swede in the Jack London story who could break trail before a sled-dog team in waist-deep snow for 12 hours with only a couple short breaks to eat dried fish. And these men, so many thousands of miles and thousands of generations apart had likely similar heartrates and fuel-preferences in these very different feats of metabolic strength.
Great comment, thoroughly enjoyed reading it and this whole CO thing not 'utilising' vs. burning additional nutrients (fat stores) seems far fetched. That would be like saying the elite athletes are just increasing their energy distribution to more inflammatory or other metabolic pathways to counteract the additional strain put on the body system by the exercise...
The zones of training make more sense, as anyone with weight will attest, their heartrate is naturally higher and jumps higher via movement than a similar person with less adiposity.
Additionally at higher lactate levels there seems to be compensatory increases in cortisol and adrenaline that while conflicting to weight loss, make perfect sense to maintaining body fat in the moment/directly after.
Also just a nitpick or pet peeve of my own, but people drinking Deuterium via DLW is a big no no and you're asking for down regulation of metabolism through destruction of your mitochondria from the deuterium molecules suddenly being vastly increased in a system that is shown to not like being anywhere above even ~135ppm.
Especially when the amount in our bodies Is equivalent to 5g of heavy water, and these guys are drinking how much???
It's about half a cup
you mention an upper limit of 5-6,000kcal/day: are there known limits on the body's ability to take in carolies from the gut? Maybe varying by protein/fat/carbs, but I could believe that if I take in (say) 10k cals of fat in 24 hours, my body is only going to absorb some maximum amount of that, based on digestive limits, with the rest being (literally) flushed away.
That's pretty much what Pontzer is saying in the book, that it's a digestive limit. But that seems mostly backed by "even the highest TDEE numbers we've ever measured aren't higher than 2.5-3x BMR" not some mechanistic explanation of the limits of the digestive system. So maybe you could figure out some way to optimize that and become an olympian :) Not sure.
Maybe if you don't explicitly support CICO orthodoxy in your book, it simply won't be published.
I just can't understand how else someone can envision, conduct, evaluate and write about studies showing that mammalian bodies are able to precisely adjust their calorie expenditure to maintain their weight, and then say you need to eat less.
Obviously, according to HIS OWN RESEARCH WHICH HE JUST SPENT A BOOK DISCUSSING, if you eat less, your body will simply lower its metabolism.
It would be like Galileo presenting his calculations showing the planetary orbits in a heliocentric system, predicting their motions elegantly and simply, and then concluding, "of course, the Earth is the centre of the universe"
> Maybe if you don't explicitly support CICO orthodoxy in your book, it simply won't be published.
Yea, probably true. And you probably don't get a PhD slot, or any interesting work. It really seems like an in-group signal.
The Galileo analogy is probably pretty apt lol. It's simply what you have to say to stay relevant. Or stay alive lol.
It's mostly unintentional motte-and-bailey caused by specialization. Academics (and Pontzer certainly is one) defer to orthodoxy whenever they stray to the edges of their particular spotlights. This is a healthy instinct, and the ones who do otherwise honestly are worse - that's how we get 'doctors' pontificating on YouTube about things of which they are totally ignorant.
[but this shades into what I wanted to say, which I'll make its own top-line comment)]
I'm not sure how to square these results with my experience. I went from almost 30 BMI to under 22 BMI using running extensively. Of course, there are always a lot of confounders, but on my weight loss plot, you can basically see the periods where I was running consistently (with the exception of the potato diet, I was not running during that yet still lost weight). If it's not CO, then it must decrease appetite and hence CI, I guess, which does seem possible based on my experience. Nevertheless, I would not discount running even low mileage (I'm running around 30 miles weekly, occasionally high intensity) as a weight loss strategy.
It seems to have worked for my 1 friend whom I mention in the article, too. He also ran at least 30 miles a week, whereas the studies Pontzer cites seem to be a bit less than that (I think up to 25mi?)
Could be that you got over that "hump" into the "it actually works" zone, or maybe you're just a good responder to exercise, or the CI decrease you mention.. who knows. I always just get hungrier from exercise :)
What would happen if you took your running back down to a, shall we say, sane level?
I read *Burn* 13 months ago and basically got the same message from it as you did. I really appreciated learning about the constrained model of energy balance and having it hammered home.
On the negative side (in addition to what you posted), the last chapter contains some really bad economics, for example claiming that all fossil fuels will be consumed in 50 years. (Making this claim is ironically as bad economically as arguing for the additive energy expenditure model is physiologically.) There was also a dose of Kendi-esque "anti-racism" mixed in throughout the book, but I assume that's because the book was published in 2021 and I suspect publishers were really pushing that narrative at that time. (I read a number of books published in 2021-2022 that all seemed to gratuitously throw in this "anti-racism" angle wherever possible. I don't think it was all on the authors, but it could have been the authors' doing in many instances. It's ultimately nearly impossible to sort out because most of these authors haven't published similar books pre- or post-2021.)
Some stuff I found interesting and worthwhile that you didn't cover in your blog post:
• His discussion of pregnancy and breastfeeding being as grueling as cycling the Tour de France gave me a new appreciation for women, and humans' general ability to reproduce.
• No matter the circumstances, the body cannot absorb more than (2.5 x BMR) kcal (≈4,000-5,000 kcal) ... and that Phelps is truly an outlier not in terms of his swimming ability but in terms of his metabolism (as you pointed out)
• When apes are put in captivity (or in conditions where they would gain weight), they gain tons of lean mass, whereas humans gain lots of fat. Peter Attia in *Outlive* points out that this is because apes have an enzyme called uricase which basically makes them unable to convert fructose into fat. My reading of all of this is that this is why apes generally don't live in cold weather environments (Japanese macaques excepted). The implication for this is that if humans had uricase, a BMI of 35 would mean people would look like NFL defensive linemen instead of sumo wrestlers.
Haha inb4 gene therapy... certainly some people are trying to work on stuff like this. I find it very scary because I think it's much easier to do crazy harm than to fix anything useful. The body is an extremely complex and fickle system, and so far, messing with singular points has pretty much gone wrong most of the time.
Agreed on the fossil fuel stuff - Pontzer must not've heard that peak oil is over and we have fracking now :D And yea also the woke stuff. Like pointing out that all that metabolic research was done by WHITE MEN. Says the white man man with the whitest name alive^^ How is that relevant to the research?!
Interestingly as he shows about Phelps, even Phelps isn't that crazy an outlier - he's at 3x instead of 2.5x. He's just a giant man with a lot of lean mass, so of course his BMR is much higher than that of most people.
> On the negative side (in addition to what you posted), the last chapter contains some really bad economics, for example claiming that all fossil fuels will be consumed in 50 years. (Making this claim is ironically as bad economically as arguing for the additive energy expenditure model is physiologically.)
I think I remember they said that 50 years ago as well. Luckily, fusion energy is just 50 years away.
Thank you for the review. As I mentioned, I have a more charitable take on Pontzer's book due to my n=1 lived experience with weight loss.
My read on the calorie discussion in this book is that humans in general have a fairly narrow band of energy expenditure, unless you exercise A LOT.
You convert food into energy, and as long as inputs are within that narrow band, your weight will eventually get to where it needs to be. That has been my experience, with a long (4 years), slow and steady down-path until things just stabilized. Silly MFP app tells me that when I exercise I can "add" 500 cals... that is not how it works for me. I need 1,900 calories (on a 3-day average in my experience) in food inputs to maintain my current weight. I do HIIT for 60 minutes x 5 per week, and it has zero bearing on the 1,900 cals.
IMHO, Doctors should stop saying "eat less, move more" and instead say "eat more whole foods minimally processed until you feel full. Exercise to help your body move better and build resiliency".
Pontzer does not answer the What (highly processed foods? PUFAs? Microplastics? Added sugars?) is causing a disconnect between satiety mechanisms and food ingested. My theory is that the satiety pathway has been broken in modern times. People stop eating when they feel full, little kids are great for that. But we seem not to get that clue anymore, or to bypass it. Food abundance does not cut it.
I am an Occam's Razor type of nerd. The constrained calorie model seem proven by the research, the fact that energy expenditure is within a narrow band to me is proven as well (exercise is fantastic for many well documented reasons, from mental acuity to chronic disease prevention), so my lesson from the book is that you need to find where your equilibrium is calorie-wise, and stick to that forever and sustainably. It may be beef and cream, or it may be fibrous veggies, or whatever rocks your boat.
On satiety (and outside the book's remit) I have found that avoiding highly processed items changed my feelings of fullness for the better.
The fact that CICO is a tautology does not make it false. I can say "today it will either rain, or not rain" and the statement will be true, but it does not explain anything beyond itself. The question we are all trying to answer is what may cause the rain, or what may cause not to rain. There are so many confounding factors (chemicals, highly processed food, thermal effect of food, etc) that picking one culprit may be impossible. But stick to your very narrow calorie band, and you shall succeed over a long period of time. Slow and steady wins the race.
Whoever wants to try my approach, DM me (I think that is possible). Thank you again, it is great to have a forum to discuss stuff like this.
> Doctors should stop saying "eat less, move more" and instead say "eat more whole foods minimally processed until you feel full
I agree with this. That's why I think it's silly to focus on "calories." If you don't remove the processed foods (and what's bad about them, wouldn't that be interesting? It's not the drying and chopping up and canning, I assume), reducing overall calories won't do much for most people. You'll just make yourself more hungry.
So "is it fruit or is it beef or is it heavy cream" is kinda the whole game. If you're just brushing that under the carpet because "they all just calories" then you've missed the entire question.
> The fact that CICO is a tautology does not make it false. I can say "today it will either rain, or not rain" and the statement will be true, but it does not explain anything beyond itself.
Exactly my point. Tautologies are true, by definition - it's just that they don't tell you anything about how to achieve fat loss.
The dishonest thing CICOpaths do is they say "CICO is always true and therefor eat less move more works." But that doesn't follow at all from CICO.
I kinda don't believe in "slow and steady." Slow and steady implies that we have a choice of how fast to go. I have yet to see anyone really have that option.
Most people don't lose anything ever. A few people lose very slowly. A few people sometimes lose very quickly. I lost 20lbs the first month on ex150, and 10lbs each the next few months. It was spectacular. Of course, it's slowed since and now I have many plateaus.
But do I think there would've been any benefit to going slower? Not at all. What would be the upside? I lost no lean mass, I have no excess skin... why weight artificially?
On the other hand, I also don't believe we have a way to "go faster" if we're honest about the goal. Yea, we can starve ourselves a little bit until our willpower runs out or our metabolism is suppressed. But as we see with many anecdotes and studies, that stuff tends to rebound, and even worse, if you actually HAVE the willpower it'll wreck your metabolism, possibly long-term.
No thanks on that front.
I like focusing on the "what's the root cause of this whole malaise" part. What's causing our fuel partitioning system to malfunction? What's causing us to divert "calories" to fat when we don't need to store any fat, and thus taking them away from our furnace, reducing our CO, and increasing our CI via hunger?
To me it always feels like we "just" have to identify the blockage, the sand in the gears, and clean it out. If we fix that, the "everything will fall into place over time" thing you mention is true.
That's what it's been for me twice now. I found some magic diet, and I just magically lost tons of weight eating ad-lib doing pretty much no exercise.
Were there any experiments in the book where they varied the diet (instead of exercise), and measured how it affects the metabolism?
Unfortunately no; Pontzer's work seems to focus exclusively on the CO side of CICO. At least in this book. The only diet things was the Biggest Loser and similar, where he briefly mentions that caloric restriction will downregulate your metabolism.
Interesting review, but a bit too harsh by claiming several times that exercise doesn’t burn calories at all. That’s just not true and could mislead people. Pontzer’s theory is that more exercise doesn’t lead to a PROPORTIONAL increase in calories burned, and I don’t think your post makes this clear enough, even though you’re pretty nit-picky about Pontzer.
In my own weight-loss experiments, I also found CICO to be unreliable, but it certainly does have some truth to it, with a few hidden catches. So far I’ve looked into things like tracking errors, constrained TEE, and the role of the microbiome, but practically speaking those have mostly been dead ends so far. I found that correctly tracking CI and CO is very hard and actually impossible to do, that my long fasting experiments might have increased my hunger by altering my microbiome and why crazy workout days at the gym + long cardio sessions all in the same day don't work.
However, I did manage to make CICO work for me eventually by tweaking my numbers—upping my tracked intake by 20% and lowering my tracked output by 20%. This tweak shows the nuances in energy balance that Pontzer talks about. Plus, it acknowledges that we all fudge the numbers a bit and our memories aren’t perfect. Of course thats only the theory, as I am not in 100% integrity following through with my CICO plans... but it's at least something.
Anyway, I like your site and your experiments. Keep up the work.
Thanks! I quoted Pontzer a lot saying the exact thing he says, so I'm hoping I got his opinion across correctly :) But yea technically what you're saying is true. Even the constrained model graph I show has the TDEE going up a little bit in the beginning. And we could probably make it go up at the very end, as you get into Michael Phelps levels of activity.
The issue I have with "playing around with my CICO until it worked" is; you don't actually know that the CICO is what made it work. Maybe it was something else you weren't even thinking of?
:) You certainly did quote him but you also make bold unsupported claims (like in the title), which is what I was getting at. Nutrition science remains a mystery. But my adjusted CICO is the best model I currently have 🤷♂️ so its valuable to me. Even if it’s just right for me by coincidence.
Well yea, the title is a bit provocative to shoot back at CICOpaths :)
I don't feel like you've quite got the point, which is that you can't really track CO without doing something like double labeled water, in which case you'll find that if you up your expenditure by running a bunch, your body will take that from other things, keeping your total CO constant.
> you can't really track CO without doing something like double labeled water
I think that statement is wrong. You can't track it precisely but that isn't what we need anyway. To lose weight we would only need to know that we are roughly in a deficit most of the time.
> if you up your expenditure by running a bunch, your body will take that from other things, keeping your total CO constant
That, again, I think is wrong. That's not Pontzer's theory. He challenges the traditional models of energy expenditure, which assume a direct and proportional increase in calorie burn with increased physical activity, and says they are overly simplistic. Instead, he suggests that while physical activity does increase total energy expenditure, the increase is not linear. BEYOND A CERTAIN POINT, the body compensates for higher activity levels by reducing energy spent on other physiological processes. The thing is, that the level of TEE above which the additional CO plateau is quite high: from what I understand, between 2500-3000. That means below that you can expect that more CO actually means more CO. And at least in my case I rarely go over 3000kcal in a day, so unfortunately his theory does not really apply to my situation that often...
That "fine tuning" method assumes naive CICO is true; though. Which Pontzer mostly disproves here. And we can't test it without ACTUALLY measuring our CI and CO, both of which are largely impossible (unless you do CO w/ DLW).
The point when the body starts compensating is pretty low, though. As Pontzer demonstrates, the Hadza walk 15k steps a day and still have the exact same TDEEs as lazy Americans. So unless you're crossing the boundary from Wal-Mart sedentary to normal, or from normal to Michael Phelps, you're unlikely to see any significant change.
I guess I'm confused by how you think you can measure TEE without double labeled water or similarly advanced technique?
And also I'm confused by how you square your statement with the quoted sections in the OP saying the Hadza of Tanzania having the same CO as sedentary people in a bunch of western countries. It seems to me that if you live a normal western life where you walk to and from your car and do occasional chores around the house, you do actually have the same TEE as the Hadza.
Thank you so much for this! I almost bought it based on one of Brad's videos. Now I feel like it's not worth the money, and I'll skip it.
For anyone coming to this post 2+ months late, the YouTube channel "Kurzgesagt" recently did a 12-min video summarizing Pontzer's body of work. https://www.youtube.com/watch?v=lPrjP4A_X4s
They did a good job summarizing everything and making it accessible to the lay person. I'm curious to see what they have to say about diet in their forthcoming video (not sure when it will drop), but definitely keep any eye out.
I had a 5 month period last year where I was running 55km / 5.5 hours per week. Almost all of this was low intensity, in my lower zone 2 heart rate range. I went from 76kg to 70kg in this time, and I was eating more than before. I didn't have any weird diet changes, or quit drinking, or have any major lifestyle changes. So if it's not calories out, what is causing me to steadily lose weight in this period? And how come I went back to maintaining weight when I stopped running and went back to eating the amount I ate before? Does getting lots of zone 1 / zone 2 kick your body into fat burning mode somehow? If the move more part of eat less move more is wrong, then I should have gained weight while running and lost weight after I stopped (or maintained in both, or maintained after I stopped running only).
55km/wk is about 35mi/wk. That's nearly 4x what they considered "high exercise" in one of the studies, and nearly 2x what they considered "very high exercise."
If you run that much, you're probably in the top 1% of the population for miles run/cardio?
Pontzer says in the book that at some extreme levels, it seems to increase CO again. Just not for the vast majority of people in the vast majority of ranges.
I was in the top 1% of Garmin users for running distance and time in my age group. But I think it's hard to argue that less than an hour a day is an extreme amount of exercise, you'd do about the same on a three day a week gym program, and casual cyclists would probably consider this a pretty moderate volume. Compared to the Hadza, this volume is tiny. You also have to consider that the equivalent intensity for someone who's unfit would be a brisk walk or uphill walk, rather than 6min/km.
What I see claimed a lot is that high volume low intensity cardio trains your body's ability to use fat for energy. See for example this post about an actually extreme version of this where someone trained 20-25hrs/week: https://alancouzens.com/blog/improving_fat_burning2.html
They were running an hour a day, 4 days a week in one of the trials. And that had pretty much zero effect.
So you could argue that it needs to be even more than that, and then you'll see SOME effect or even big one... but I'm not sure I believe that to be true for most people.
It might just be that a small % of people are hyper responders to exercise to begin with, and "long bouts of exercise w/ no benefits and lots of downsides" filters out everyone else.
And even the Hadza don't burn more calories than sedentary Americans, so why bother emulating their exercise routine?
My understanding is that *low intensity* cardio (zone 1/2) trains the fat-burning systems to be more efficient - so that you can burn more fat per hour. This seems kind of useful if you want to lose fat (weight). But it's important that it's low intensity, you're supposed to feel fresh at the end of it, not knackered.
The study you mention maybe(?) had people working *hard* for 1 hour, 4 days a week - that's a different thing entirely. Creates a stress on the body that needs recovery, and the energy source would be more glycogen and less fat so it doesn't train fat-burning systems in the same way.
Yea these people were trying to "burn carolies to lose fat" not to train their fat burning systems. I do enjoy going for walks, so I wonder if this goes very well with being keto adapted; if both are very amenable to fat burning. I'd call my walks invigorating, when I return, I feel fresher than when I left. Pretty much no exertion unless there happens to be a hill. Is that zone 1?
Yeah, that's it, definitely goes well with low carb / keto. 👍
Harder walks with faster pace / stairs / longer times / rucking / etc are probably zone 2 if the effort level is not too high. Exact definitions vary and are non-trivial to test for, but that's close enough. I just go by how long I could maintain that amount of effort for. If it's "I could go hiking at this effort level all day" it's zone 2, if it's "I'm burned out and need to rest after an hour" then it's zone 3 (or higher).
i have to ask - did someone set your autocorrect to spell it carolies instead of calories on your entire substack?
They're the same wrod?
I think part of the problem with books like this is that publishers will try to get the author to make prescriptions after describing a problem, which forces them out of their area of expertise. Marx got some stuff right about capitalism but his proposed solution lead to misery and death on a huge scale.
More interesting would be the question if exercise doesn't increase the "CO" part what does? Same goes for changing the CI part of the equation how does it impact CO?
I think that there isn't one blanked thing that always make CO go up w/o context.
Both CI (via hunger) and CO (via "feeling energized" and NEAT and BMR and so on) are normally pretty tightly regulated by the body.
I think that you can "vastly increase" your CO with "this one little trick" but only if your metabolism is currently broken, and the regulator isn't working as intended. I.e. if you've been starving yourself and your metabolism is vastly depressed, like with the biggest loser people. Just eating more will vastly increase your CO. I think that's not controversial, it's just that in most people it'll lead to regaining all the fat they just starved off. (I think ex150 type diets could be a nifty trick to avoid the regain here!)
I also think that if you're eating a "normal" amount and have say a TDEE of 3,200kcal/day, and then you stuff yourself to the brim with more extra food, your CO would likely go up a bit to maybe 3,300-3,500. Maybe even higher. Anecdotally there are keto people who've eaten 4,000kcal/day for a period without gaining any fat. I've done it myself, twice, for about a month each.
But there's a limit as Pontzer shows, I doubt that you can get your TDEE to 10k via overfeeding. Maybe not even 5k.
Another factor is that we think PUFAs decrease your CO, and increase your CI by sneakily channeling a % of all your CI into adipose tissue no matter what (incorrect "fuel partitioning").
So stopping PUFA consumption, and depleting yourself of PUFAs, would over time correct the regulatory mechanism and thereby (positively, hopefully) manipulate your CI and CO.
Just acutely, PUFAs trigger the endocannabinoid system, which makes your CI go up by increasing your hedonic appetite. Cutting out the PUFAs will likely decrease spontaneous CI.
Basically it's context all the way down, and it's all marginal :)
Now I'm interested in what that actual calorie out from activity curve looks like. Probably like the tangent curve or something? Where are the actual inflection points, and how does genetics impact those?
I suppose you'd have to run DLW on the same individual over and over, every 500kcal of (hypothetical) exercise added or so, and graph that? I think it's still way too much work/too expensive for that.
I’m not sold on the methodology. An unchanged ratio 2H/18O can mean that nothing has been burned, OR that a lot of calories has been burned, but that almost all O of CO2 comes from O2 from respiration ?
In other words, it looks like to me this methodology can’t distinguish between "more exercise don't burn calories" and "more exercise burn calories, but H2O mostly stays H2O, O2 in breathed out CO2 mostly come from breathed in O2". Or am I missing something obvious ?
Hm wouldn't a lot of O2 coming in through respiration be happening anyway? Unless you somehow managed to only burn the O from incoming O2 and not the one from the water.. I guess I don't really know how these pathways work exactly, e.g. if there are separate "pools" or "streams" or what not. Above my pay grade I guess :)
This is great. I quite liked the book for the CO findings and the use of DLW was interesting. I did read previous reviews before buying that it wasn’t a weight loss’ book & as you say it doesn’t offer any real solutions. I like how you highlight the cocky arrogance of Pontzer and that of the others who all cozy up in their elite circles of smugness. However IMO, without doubt, this is important work and can’t be ignored.
Yea agreed. Glad I wasn't the only one feeling like he was a bit cocky for essentially not having any answer either. I'm all for disproving things, but then we shouldn't shit on people trying new solutions.