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.
> debunk the popular myth for my friends that exercise burns a lot of calories
Depends on your level of exercise. I often cycle 100km per day and can tell you if I ate only the 2000 kcal I hypothetically need I would go into a strong deficit.
Balancing health while being productive as an average adult seems like an impossible equation today.
Many people tell me I need to lift weights to lose weight.
On mornings when I actually put in real effort, I pay for it with a significant cognitive performance penalty for the remainder of the day. I want to do nothing more than sleep an hour after a workout, which is bad timing, because that's when I need to clock into work.
I stay hydrated, get enough sleep, etc. People tell me that I'm over training, which is ridiculous, because anything less would be easy and contravene the purpose of the workout.
This is why I prefer to exercise in the evening, but there are known negative effects [0] of physical exertion on sleep quality.
If I actually did all the exercise I needed to do at the gym in the morning, then I'd probably have to sleep at 9:00 PM and wake up at 4:00 AM. There's no room to live in that schedule.
Hate to be the bearer of bad news, but you are likely over training. Check out heart rate zones, optimal workouts for weight loss/muscle gain. IE for endurance sports most of your training time should be zone 2, which if casually “a level of breathing where you could have a conversation”. So not breathing hard. It’s counterintuitive, but you should do workouts pretty close to easy.
Something else you might try is changing your diet. After I became a vegetarian and eliminated refined sugar and excess sodium from my food, my health improved, as well as my sleep. I am no longer pre-diabetic. And the food that I eat is wonderful, many different ways of preparing beans and lentils for protein instead of meat.
Exercise is a magic pill in every sense except for losing weight. That's almost entirely controlled by your diet.
If you're exercising to lose weight, you're probably thinking that more exercise means more weight loss, which means that you could be overtraining.
I recently got a second Apple Watch to wear to bed to track my sleep, and it's given me some really great insights into when I'm hitting the red zone and need to dial back training. For exercise, more intensity is not always better. What matters is consistency, not consistently high intensity.
> Many people tell me I need to lift weights to lose weight.
No you dont. Exercise does help, and has many other benefits but is not the main driving factor for losing weight. Diet is by far the most important one. Calories intake vs expenditure is the only thing you need to worry about if your primary goal is weight loss.
> People tell me that I'm over training, which is ridiculous, because anything less would be easy and contravene the purpose of the workout.
This doesn't mean you aren't over training.
If it's strength training... Without knowing the specifics what you are describing sounds like too much volume (and training for hypertrophy). Lower reps (3-5) & higher weight will have more of a strength stimulus and be less taxing.
If it's cardio... you probably should be at a lower intensity and going for longer.
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.
It's well-structured and the message is clear. Are we intentionally prompting LLM to write badly now? Do we have to manually write bad essays to avoid AI accusation?
Why is this AI writing accusation necessary? Plenty of humans write this way. Have you ever read pre-AI content marketing articles? If you've learned a bunch content marketing advise then you'll see those patterns that you now associate with "AI writing" were already all over the place. Baity titles like "Why it's bad that X did Y" or "<explanation of the problem>. Want to be freed from worrying about this? Use $OUR_BRAND", urgh, once you learn those patterns you can't unsee it.
Granted, you don't like to like this style of writing, I don't either. But you don't have to auto-accuse AI writing either. Also, there's nothing wrong with using AI to rephrase a manually written text for better readability, plenty of people use AI for that too rather than writing the entire thing.
Usually, I can easily tell bad AI slop, because it is just that - sloppy - the bullet points, the 'delving' and all that.
But how can you tell this article was also AI-tainted?
On a second skim, I can sort of sense some of it - the bulletpoint-enthusiasm, the idiosyncratic segues (?) that link sections/paragraphs of the text.
But it didn't trigger for me immediately, or cause me concern..?
I'm worrying that soon, I will have to hunt for non-AI essays by them just being worse written/more 'crude' and not as eloquently written as an AI would do :-/
Basically, seeking out "authentic human slop".
I wanted to test my theory that "don't use cliche'd language" helps with that, but incredibly the essays ChatGPT is giving me today don't have any of the tells. How do I get it to give me slop?
I asked "Can you give me a short essay on the history of fire." Maybe the type of writing requested has a massive effect on the language used?
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).
I can see why every vegetarian should take it. But if you eat meat regularly, your creatine stores will be at a level where you'd probably only see a cognitive benefit at times of sleep deprivation. But if you're regularly sleep-deprived, then you'd do best by addressing your sleep issues.
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.
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.
The way neurons and synapses work you spend a lot of energy keeping them ready to fire. How often they actually fire is a smaller cost compared to maintaining them in ready state.
We end up using 100W (2000kcal/day) for the whole body, or about 20W for the nervous system alone (though a nervous system alone wouldn't be able to survive). That's comparable to what a modern laptop uses. Sure, that laptop can't run a large LLM at any reasonable speed, but it can do basic math far better than my brain. By a comically large margin. Just a consequence of the very different architectures chosen
Current AI systems aren't biomimicry; they run a simulation of something vaguely similar to neurons. This is rather like "why does it take more processing power to emulate a PS2 than the original PS2 had".
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.
Because computers use digital circuits which are not allowed to make mistakes, i.e., they amplify each signal during every step as it passes through the system.
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.
My thinking was that its sort of like an engine spinning at idle vs when the gear's engaged, in either case the engine is still spinning and using fuel, just more so when its engaged, as opposed to an electric motor.
I know the metaphor isn't exact, it's just how i thought of it.
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].
This kind of correlates with a wisdom I've heard before:
You don't suffer from a lack of time, but rather a lack of energy.
And actually, you don't suffer from a lack of energy, but a lack of activation energy.
We colloquially refer to activation energy as motivation. But maybe that's not the whole story. Some of it is willpower and personality, but maybe some of it is a buildup of adenosine.
This squares with my personal experience. It's harder to start things after day's worth of intense mental effort.
[+] [-] sdfhbdf|25 days ago|reply
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.
[+] [-] jahnu|25 days ago|reply
Can you expand on that please? Because I can tell you as a matter of fact that when I go for a run for an hour I burn well over 800 calories.
[+] [-] sva_|24 days ago|reply
Depends on your level of exercise. I often cycle 100km per day and can tell you if I ate only the 2000 kcal I hypothetically need I would go into a strong deficit.
[+] [-] Rapzid|25 days ago|reply
[+] [-] evanjrowley|24 days ago|reply
Many people tell me I need to lift weights to lose weight.
On mornings when I actually put in real effort, I pay for it with a significant cognitive performance penalty for the remainder of the day. I want to do nothing more than sleep an hour after a workout, which is bad timing, because that's when I need to clock into work.
I stay hydrated, get enough sleep, etc. People tell me that I'm over training, which is ridiculous, because anything less would be easy and contravene the purpose of the workout.
This is why I prefer to exercise in the evening, but there are known negative effects [0] of physical exertion on sleep quality.
If I actually did all the exercise I needed to do at the gym in the morning, then I'd probably have to sleep at 9:00 PM and wake up at 4:00 AM. There's no room to live in that schedule.
[0] https://dx.doi.org/10.1038/s41467-025-58271-x
[+] [-] soared|24 days ago|reply
[+] [-] diogenes_atx|24 days ago|reply
[+] [-] EPWN3D|24 days ago|reply
If you're exercising to lose weight, you're probably thinking that more exercise means more weight loss, which means that you could be overtraining.
I recently got a second Apple Watch to wear to bed to track my sleep, and it's given me some really great insights into when I'm hitting the red zone and need to dial back training. For exercise, more intensity is not always better. What matters is consistency, not consistently high intensity.
[+] [-] ap-hyperbole|24 days ago|reply
No you dont. Exercise does help, and has many other benefits but is not the main driving factor for losing weight. Diet is by far the most important one. Calories intake vs expenditure is the only thing you need to worry about if your primary goal is weight loss.
[+] [-] rKarpinski|24 days ago|reply
This doesn't mean you aren't over training.
If it's strength training... Without knowing the specifics what you are describing sounds like too much volume (and training for hypertrophy). Lower reps (3-5) & higher weight will have more of a strength stimulus and be less taxing.
If it's cardio... you probably should be at a lower intensity and going for longer.
[+] [-] ChoGGi|24 days ago|reply
Exercise a little earlier in the evening?
[+] [-] xiphias2|24 days ago|reply
This is stupid. All you need to do is to get used to being hungry to the point of losing 0.1kg/day and measure yourself a lot (I'm doing the same).
Actually for me working out increases my appetite, and I feel like I have to eat so thar the gym session doesn't go wasted.
[+] [-] aaronbrethorst|25 days ago|reply
[+] [-] nothrabannosir|25 days ago|reply
[+] [-] raincole|25 days ago|reply
[+] [-] FooBarWidget|24 days ago|reply
Granted, you don't like to like this style of writing, I don't either. But you don't have to auto-accuse AI writing either. Also, there's nothing wrong with using AI to rephrase a manually written text for better readability, plenty of people use AI for that too rather than writing the entire thing.
[+] [-] fifticon|25 days ago|reply
I'm worrying that soon, I will have to hunt for non-AI essays by them just being worse written/more 'crude' and not as eloquently written as an AI would do :-/ Basically, seeking out "authentic human slop".
[+] [-] amelius|24 days ago|reply
[+] [-] andai|25 days ago|reply
I asked "Can you give me a short essay on the history of fire." Maybe the type of writing requested has a massive effect on the language used?
[+] [-] dgxyz|25 days ago|reply
[+] [-] darthbanane|25 days ago|reply
[+] [-] hpdigidrifter|25 days ago|reply
Even once is rare unless I've been out drinking for the night.
[+] [-] bitshiftfaced|24 days ago|reply
I can see why every vegetarian should take it. But if you eat meat regularly, your creatine stores will be at a level where you'd probably only see a cognitive benefit at times of sleep deprivation. But if you're regularly sleep-deprived, then you'd do best by addressing your sleep issues.
[+] [-] omgmajk|25 days ago|reply
[+] [-] nfg|25 days ago|reply
[+] [-] 21asdffdsa12|25 days ago|reply
[+] [-] podgorniy|25 days ago|reply
[+] [-] baron816|25 days ago|reply
[+] [-] bob1029|25 days ago|reply
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.
[+] [-] wongarsu|25 days ago|reply
We end up using 100W (2000kcal/day) for the whole body, or about 20W for the nervous system alone (though a nervous system alone wouldn't be able to survive). That's comparable to what a modern laptop uses. Sure, that laptop can't run a large LLM at any reasonable speed, but it can do basic math far better than my brain. By a comically large margin. Just a consequence of the very different architectures chosen
[+] [-] pjc50|24 days ago|reply
[+] [-] alex43578|25 days ago|reply
[+] [-] kergonath|25 days ago|reply
"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.
[+] [-] amelius|24 days ago|reply
[+] [-] suzzer99|25 days ago|reply
[+] [-] haritha-j|25 days ago|reply
I know the metaphor isn't exact, it's just how i thought of it.
[+] [-] johnfn|25 days ago|reply
[+] [-] misja111|24 days ago|reply
[+] [-] joduplessis|25 days ago|reply
[+] [-] sdfhbdf|25 days ago|reply
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
[+] [-] koliber|24 days ago|reply
You don't suffer from a lack of time, but rather a lack of energy. And actually, you don't suffer from a lack of energy, but a lack of activation energy.
We colloquially refer to activation energy as motivation. But maybe that's not the whole story. Some of it is willpower and personality, but maybe some of it is a buildup of adenosine.
This squares with my personal experience. It's harder to start things after day's worth of intense mental effort.
[+] [-] user____name|24 days ago|reply
https://www.science.org/content/article/mentally-exhausted-s...
[+] [-] coolThingsFirst|24 days ago|reply
Willpower is limited. Hard workout means intense cognitive effort is much harder to pull off.
[+] [-] MagicMoonlight|24 days ago|reply
[+] [-] niemandhier|24 days ago|reply
It takes at least a week until it gets stored in the brain if you start taking it.
[+] [-] tsoukase|24 days ago|reply
For me as N=1, training after thinking is easier than the reverse.
[+] [-] ifh-hn|25 days ago|reply
[+] [-] piskov|24 days ago|reply
Found myself practically stop longing for sweets during programming; have more energy during workouts (135 KG bench press and all the other stuff).
5 g daily is what considered to saturate your muscles.
Some report that any additional helps cognitive tasks (but I haven’t seen definitive studies besides the sleep deprivation).
I take 7.5 g
[+] [-] soared|25 days ago|reply
[+] [-] xnx|24 days ago|reply