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Comment by eimrine | Hacker News Reader

So why I am consuming so much carbohydrates while intellectual job? Kind of too much resistance of wires or something fixable?

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0.2 watts is 172 (k)calories per hour, which isn't all that small (in addition extra load on the rest of the body, such as the heart, lungs, liver, etc. to support that metabolism)

Forgive me if I'm being dense, but that number seems really implausible to me. 172 kCal an hour is (assuming just waking hours consume calories) about 2700 kCal just from the cortex over the course of a day, which is more than the average Total Daily Energy Expenditure.

Would that mean 0.2 watt is the maximum energy expenditure of the cortex and not the average?

I’m usually bad at arithmetic, but I think it’s only 172 cal ie 0.172 kcal, no?

0.2W x 3600s -> 720J -> 172 cal

Further, the human body is only about 30-40% efficient at turning calories into work.

You mean cal, not kcal.

You're missing a conversion here.

0.2 watt is 172 small calories. A large "food Calorie" is a kilocalorie, the energy required to heat one kilogram of water by 1 degree C. The small gram calorie is the energy required to heat one gram (or one mililitre) by one degree C. These may be distinguished by a large or small 'c', where "Calorie" -> kilogram calorie and "calorie" -> gram calorie. I prefer spelling out "kilocalorie" where there's any possibility for confusion.

0.2 watt is 0.172 kilocalories per hour, or about 4 kcal/day.

No, it's 172 calories per hour, not kcal, which is absolutely tiny compared to our metabolism.

"The average human, at rest, produces around 100 watts of power"

http://large.stanford.edu/courses/2014/ph240/labonta1/

The same happens to me! My feeling is that my body asks to consume carbohydrates to supply the brain with readily available energy.

> So why I am consuming so much carbohydrates while intellectual job?

How much carbohydrates did you expect you should consume?

No expectation. Just took pork as a breakfast for few days of hackathon but have not consumed any of that. But pork is meal N1 for me when I'm doing hard work like digging a ground or travelling on a bicycle.

> why I am consuming so much carbohydrates

Poor availability of healthy + low calories + palatable + inexpensive food in developed countries.

The obesity crisis comes from that.

I find it super weird that my food intake nor my sleep duration is correlated with my brain use. There are days where I will hardcore hyperfocus learning technical scientific papers all day and also deeply think/debate about a complex topics for hours and other days where my brain will be complely un-stimulated and yet as I said, no variation. It's absurd.

A tangeant would be: do highly intellectual people have shorter lifespan because their body would trade-off energy for their brain thus limiting the supply on other organs and hence creating deficit in e.g. mitochondria bioenergetics?

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