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RealLife_IronMan t1_itffpur wrote

Imo, we need to understand a few basic concepts to answer this

  1. For all actions (physical and mental alike) we use energy. So when you think your brain requires energy.

  2. The human body (unlike plants) can produce energy via 2 main sources a. The food we eat is converted directly to glucose (unless you’re on a ketogenic diet then it gets converted to ketones first) and then it is used to provide energy to the body. b. In a fasted state due to lack of glucose our body tends to break up fats and sometimes muscles to get ourselves the required energy…

Do (1) and (2) combined suggest that when you think a lot you’ll end up buri h some sort of calories but whether it’d be fat or muscle or just the meal you had last would be dictated by several governing factors.

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Acrobatic-Book t1_itftgp9 wrote

Some additions / corrections:

  1. Your brain works all the time. While it's using a big amount of energy for all the processing it's doing, it mainly redistributes this energy to the tasks at hand. So "thinking hard" won't increase your energy consumption that much.
  2. The food we eat is not necessarily converted to glucose. While sugar are converted to glucose, fatty acis and ammino acids can either be used by neoglucogenesis (conversion to sugar) in the liver or be can be directly used as fuel by your muscles. The brain is indeed a bit special that it can only use glucose or ketone body's as fuel - ketone body as like fatty acids in disguise.

So while thinking could increase your energy uptake minimally, a more substantial influence could be the release of stress hormones (aka adrenaline) which increase the metabolic activity of the whole body

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Triabolical_ t1_itjoewn wrote

One correction:

Fatty acids cannot be converted to glucose - if that was possible we likely wouldn't need ketosis as the liver could just convert fat to glucose.

The glycerol that holds fatty acids together as triglycerides can be converted to glucose.

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Acrobatic-Book t1_itk7fvv wrote

Oh true, I remembered that wrong (and makes more sense this way ^^). Thx for the correction :)

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