Monday, April 26, 2010

Do knowledge workers burn more cerebral calories?

Our brains burn a lot of the calories we eat [1]. So are knowledge workers working out?

Alas, probably not ...
Appraising the brain's energy budget (PNAS 2002)
... In the average adult human, the brain represents about 2% of the body weight. Remarkably, despite its relatively small size, the brain accounts for about 20% of the oxygen and, hence, calories consumed by the body (1). This high rate of metabolism is remarkably constant despite widely varying mental and motoric activity...

Later articles suggest that while brains use a lot of calories, and are thus a very expensive evolutionary development, they don't use the calories for thinking. Brain calories are primarily consumed in "intrinsic activites" unrelated to environmental stimulus -- presumably maintenance functions of some sort.

So we knowledge workers don't get any caloric credit for thinking, and since we usually think while sitting (very bad) we're really pro blubber.

[1] We also know human brains are smaller and probably more efficient than they used to be. Of course, so are computers.

Update: I suppose memory formation might be energy intensive, so maybe forming more memories could burn calories?

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