[Almaviva]

I'm wondering if it's ever been shown that doing something mentally difficult consumes more energy than doing something where the brain is active but that isn't perceived as difficult?

Another explanation could be that the precursor to grinding in EQ is the urge to do things like searching for edible plants or animal tracks, carving tools, cleaning the home, and other things which have obvious evolutionary benefit.

[goodside]

The brain consumes more sugar when it's thinking harder. Before functional MRIs were invented, brain imaging required injecting irradiated glucose and scanning for radioactivity in the brain. Tasks requiring attention and self-discipline deplete glucose, and people demonstrably have higher vigilance for repetitive attention-heavy tasks when they've been injected with sugar.

This has been known to science for at least a century. The slightest glimpse at Wikipedia would have sufficed.

[Almaviva]

> people demonstrably have higher vigilance for repetitive attention-heavy tasks when they've been injected with sugar

That's not at all the same as saying that more difficult tasks actually consume more sugar, any more than programming must consume caffeine because coffee makes some people more focused on it.

[goodside]

Meanwhile, in reality, where evidence extends further than whatever I happen to mention, it does deplete glucose.

[Almaviva]

I don't know why you need to be rude and condescending. I don't know much about these things, but cursory research shows that these are at least good questions: http://www.epjournal.net/filestore/ep08244259.pdf

"It does deplete glucose" seems to be in question, doesn't it?

[killerdark]

Good question. As repetition sets in, more of the task is probably moved to the muscle memory part of the brain, but this does not necessitate a lower energy consumption.