I found the AI writing of this post to really detract from its message. Give your agent meaningful writing samples of your own work and use those as a ‘style transfer’ basis for blog posts to get something far more true to your own voice.
I've also been interested for some time in how metabolism works and wanted to debunk the popular myth for my friends that exercise burns a lot of calories, since I was under the impression that around 80% of energy we burn is just by "living" - breathing and thinking.
Reading this article I'm a little confused by the author's conflation of brain energy and the energy expenditure of the body as a whole. In the beginning they mention:
> "Your brain consumes roughly 20 to 25% of your body's total energy at rest"
while later they say:
> "Even chess grandmasters, who sit for hours in states of intense concentration, burn only about 1.67 calories per minute while playing, compared to 1.53 calories per minute at rest"
That second figure seems to refer to whole-body expenditure, not just the brain. And intense cognitive work doesn't happen in a metabolic vacuum - there's increased cerebral blood flow, elevated sympathetic nervous system activity, changes in heart rate variability, hormonal shifts (cortisol, adrenaline). These all have systemic metabolic costs that go beyond the glucose the neurons themselves consume. So the "it's just a banana and a half" framing might be undercounting by quietly switching between brain-only and whole-body measurements.
Also somewhat related - the link to businessinsider about chess grandmasters is broken, but another very interesting rabbit hole here is how energy expenditure is actually measured. A lot of what consumer devices and even many studies report is based on proxy biomarkers like heart rate, HRV, weight, age, and sex, run through linear regression models. True calorimetry (indirect via gas exchange, or direct in a metabolic chamber) is expensive and impractical outside lab settings. That means the precise calorie figures cited with such confidence - the "100 to 200 extra calories" from a day of thinking, or the per-minute burn rates of chess grandmasters - likely carry wider error bars than the article suggests. We don't really have a great way to measure real-world energy expenditure accurately at the individual level, which makes me a bit cautious about the neat narrative of "thinking is calorically cheap, full stop."
That said, the core point about adenosine accumulation and perceived exertion affecting training quality is fascinating and well-supported — that part of the article is genuinely useful regardless of the calorie accounting.
Was expecting the article to mention creatine which interacts with ATP. It's a supplement that's so well studied that almost everyone should take it, even if you don't workout at all.
In my experience it has helped tremendously with mental endurance (n=1 but there are some studies that support it, especially in older people with cognitive decline).
Creatine monohydrate (and seemingly HCL too, though not tested long term) kind of makes me constipated. I'd like to take it, because I lift weights quite often, but it just messes with my stomach too much.
Second anecdote, I take between 10 and 15 grams. I don’t experience cognitive effects at lower doses (though my weightlifting endurance is still higher on lower doses). I also don’t eat meat so don’t have any incidental consumption
Shouldn't the chemistry hide the usage of calories by the brain? It gets basically a supply run at night - when its washed with lymph, sugar supplied and then subsists on that for new memory formation and computation with small scale supplies delivered during the day via the blood stream? So a hard thinking experience should show up downstream as calorie usage during the following sleep?
Is anyone here able to offer an explanation for why our brains are able to do really complex tasks without using much energy, at least compared to AI systems?
The brain relies on discrete, sparse events in space and time to handle computation.
Most of the computation and learning that occurs is attributable to the relative timing of spiking events. A lot of information can be encoded in the delay between 2 spikes. The advantage of biology is that there is no explicit quantization of the time domain that must occur. Biology gets to do a lot of things "for free". Simulating causality in a computer in a similar way requires a priority queue and runs like ass by comparison.
Why would they not be? A brain and a computer are completely different things. They don’t do the same thing and they don’t work the same way at all.
"Artificial neuron" was a useful metaphor at the beginning, but they really are a very simplified model based on what some people understood of neurology back then. They are not that useful to get insights into how actual neurons work.
If I'm not in flow state focusing on some programming problem, my brain is still going a million miles a minute pontificating about 10 different threads of nonsense at once. So I could see where focusing on one task doesn't actually burn any more energy, it just pulls in all those other workers and puts them to work on one thing.
The product that this article is advertising seems to be pretty inaccurate and their marketing seems to be burying that information.
The big copy on the front page says:
> Your Apple Watch *tracks* VO2 Max—one...
While you have to read through FAQ where you see:
> The watch *estimates* your cardio fitness during outdoor activities and stores it in Apple Health, which our app reads automatically.
All emphasis are mine.
I think it's a little disingenuous to sell this as "Your VO2 Max, finally visible" when it's actually just an estimate from a watch, based on biomarkers. When the real VO2 is measured in a lab with a more involved equipment.
A 2025 validation study involving 30 participants found that Apple Watch underestimated VO2 max by a mean of 6.07 mL/kg/min (95% CI 3.77–8.38) when compared to indirect calorimetry, the gold standard method. The mean absolute percentage error (MAPE) was 13.31%, and the limits of agreement showed considerable variability ranging from -6.11 to 18.26 mL/kg/min [1]. Another 2024 study found similar results, with the Apple Watch Series 7 showing a MAPE of 15.79% and poor reliability (ICC = 0.47) [2].
I found the AI writing of this post to really detract from its message. Give your agent meaningful writing samples of your own work and use those as a ‘style transfer’ basis for blog posts to get something far more true to your own voice.
Or just fucking write it yourself!
I've also been interested for some time in how metabolism works and wanted to debunk the popular myth for my friends that exercise burns a lot of calories, since I was under the impression that around 80% of energy we burn is just by "living" - breathing and thinking.
Reading this article I'm a little confused by the author's conflation of brain energy and the energy expenditure of the body as a whole. In the beginning they mention:
> "Your brain consumes roughly 20 to 25% of your body's total energy at rest"
while later they say:
> "Even chess grandmasters, who sit for hours in states of intense concentration, burn only about 1.67 calories per minute while playing, compared to 1.53 calories per minute at rest"
That second figure seems to refer to whole-body expenditure, not just the brain. And intense cognitive work doesn't happen in a metabolic vacuum - there's increased cerebral blood flow, elevated sympathetic nervous system activity, changes in heart rate variability, hormonal shifts (cortisol, adrenaline). These all have systemic metabolic costs that go beyond the glucose the neurons themselves consume. So the "it's just a banana and a half" framing might be undercounting by quietly switching between brain-only and whole-body measurements.
Also somewhat related - the link to businessinsider about chess grandmasters is broken, but another very interesting rabbit hole here is how energy expenditure is actually measured. A lot of what consumer devices and even many studies report is based on proxy biomarkers like heart rate, HRV, weight, age, and sex, run through linear regression models. True calorimetry (indirect via gas exchange, or direct in a metabolic chamber) is expensive and impractical outside lab settings. That means the precise calorie figures cited with such confidence - the "100 to 200 extra calories" from a day of thinking, or the per-minute burn rates of chess grandmasters - likely carry wider error bars than the article suggests. We don't really have a great way to measure real-world energy expenditure accurately at the individual level, which makes me a bit cautious about the neat narrative of "thinking is calorically cheap, full stop."
That said, the core point about adenosine accumulation and perceived exertion affecting training quality is fascinating and well-supported — that part of the article is genuinely useful regardless of the calorie accounting.
Was expecting the article to mention creatine which interacts with ATP. It's a supplement that's so well studied that almost everyone should take it, even if you don't workout at all. In my experience it has helped tremendously with mental endurance (n=1 but there are some studies that support it, especially in older people with cognitive decline).
Creatine monohydrate (and seemingly HCL too, though not tested long term) kind of makes me constipated. I'd like to take it, because I lift weights quite often, but it just messes with my stomach too much.
Creatine ruins my sleep Find myself getting up multiple times a night to pee.
Even once is rare unless I've been out drinking for the night.
That's interesting. I'm having the same problem. I usually have it after my workout in the evening. Should I try moving it to earlier in the day?
How much are you taking?
5 grams a day, personally, based on a large body of evidence that it is a good amount.
> personally
You’re not having someone else take it for you?
Second anecdote, I take between 10 and 15 grams. I don’t experience cognitive effects at lower doses (though my weightlifting endurance is still higher on lower doses). I also don’t eat meat so don’t have any incidental consumption
That seems like a lot to take daily. Most studies have settled on loading isn’t needed and 5g/day is enough.
I just take 5g/day with my morning coffee/water.
> I also don’t eat meat
This is probably an important difference from the average participant of those studies.
Shouldn't the chemistry hide the usage of calories by the brain? It gets basically a supply run at night - when its washed with lymph, sugar supplied and then subsists on that for new memory formation and computation with small scale supplies delivered during the day via the blood stream? So a hard thinking experience should show up downstream as calorie usage during the following sleep?
Is anyone here able to offer an explanation for why our brains are able to do really complex tasks without using much energy, at least compared to AI systems?
The brain relies on discrete, sparse events in space and time to handle computation.
Most of the computation and learning that occurs is attributable to the relative timing of spiking events. A lot of information can be encoded in the delay between 2 spikes. The advantage of biology is that there is no explicit quantization of the time domain that must occur. Biology gets to do a lot of things "for free". Simulating causality in a computer in a similar way requires a priority queue and runs like ass by comparison.
Why would they not be? A brain and a computer are completely different things. They don’t do the same thing and they don’t work the same way at all.
"Artificial neuron" was a useful metaphor at the beginning, but they really are a very simplified model based on what some people understood of neurology back then. They are not that useful to get insights into how actual neurons work.
Completely different architectures and mechanisms. Machine learning draws inspiration from some biology concepts, but implements it in different way.
If I'm not in flow state focusing on some programming problem, my brain is still going a million miles a minute pontificating about 10 different threads of nonsense at once. So I could see where focusing on one task doesn't actually burn any more energy, it just pulls in all those other workers and puts them to work on one thing.
The product that this article is advertising seems to be pretty inaccurate and their marketing seems to be burying that information.
The big copy on the front page says:
> Your Apple Watch *tracks* VO2 Max—one...
While you have to read through FAQ where you see:
> The watch *estimates* your cardio fitness during outdoor activities and stores it in Apple Health, which our app reads automatically.
All emphasis are mine.
I think it's a little disingenuous to sell this as "Your VO2 Max, finally visible" when it's actually just an estimate from a watch, based on biomarkers. When the real VO2 is measured in a lab with a more involved equipment.
A 2025 validation study involving 30 participants found that Apple Watch underestimated VO2 max by a mean of 6.07 mL/kg/min (95% CI 3.77–8.38) when compared to indirect calorimetry, the gold standard method. The mean absolute percentage error (MAPE) was 13.31%, and the limits of agreement showed considerable variability ranging from -6.11 to 18.26 mL/kg/min [1]. Another 2024 study found similar results, with the Apple Watch Series 7 showing a MAPE of 15.79% and poor reliability (ICC = 0.47) [2].
[1]: https://journals.plos.org/plosone/article?id=10.1371%2Fjourn...
[2]: https://biomedeng.jmir.org/2024/1/e59459
yeah there's no reliable way to measure VO2 max without breathing into tubes.
Quadruple espresso + some good deathcore solves this pretty nicely for me.
I train in the morning so it looks like I avoid this completely. Also the calculator at the end... Just assume an Apple watch.
Yeah, this seems like an obvious solution. If possible, move your workout to before work.
Holy 3-6mg of caffeine per kg is a shit ton. That’s 2-4 cups of coffee for me!
https://vo2maxpro.com/blog/does-caffeine-improve-vo2-max
They list a study and more info on that page. Probably why almost all pre-workouts include caffeine. Some push for 300mg per serving.
Yohimbe gives some weird heart effects also.
Seven for my ~140kg arse. Not sure how healthily this scales.