how thinking uses energy

here is a shorter but still complete, high-value version of the notes. nothing important is removed — only repetition and long explanations are condensed.

1. how thinking uses energy

brain’s fuel

• brain runs on glucose, taken directly from blood, not stored.
• even if your body has energy, your prefrontal cortex (pfc) can run low in real time.
• deep thinking rapidly increases:
  • glucose use
  • oxygen demand
  • dopamine, norepinephrine, acetylcholine usage

where glucose is stored

• liver glycogen (accessible)
• muscle glycogen (not accessible to brain)
• so you can eat enough but still experience mental glucose dips.

what happens when glucose drops

• weak working memory
• forgetting recent moves, numbers
• brain fog
• chaotic thoughts
• inner noise
• fast thinking

2. how many calories thinking burns

baseline

• brain uses 20% of daily calories.

experiments

• chess grandmasters: burn 4000–6000 calories/day during tournaments due to high cognitive load.
• mri studies: difficult thinking ↑ pfc glucose use by 12–25%.
• mental work study: ~100 extra calories burned during 3 hours of heavy thinking.

conclusion

• thinking is not exercise-level burn per minute…
• but long days of mental stress significantly drain energy.

3. working memory = brain’s ram

function

holds short-term info for a few seconds:

• game moves
• ball-by-ball details
• numbers someone tells you
• recent conversations
• tracking positions in games

why your working memory feels weak

• constant internal thinking + self-talk
• planning and analyzing all day
• fast or intrusive thoughts
• overstimulated brain
• low dopamine periods
• glucose dips
• overactive default mode network (dmn)

all of this occupies your ram, so new info cannot enter or stay.

result

• you forget recent events
• need to “force” yourself to remember
• lose track during games
• mix numbers
• can’t recall details unless you consciously switch on memory

4. prefrontal cortex overstretching

you overstretch the pfc when you:

• think all day
• simulate future scenarios
• talk to yourself internally
• consume too much information online
• process complex ideas
• plan constantly
• analyze productivity
• handle emotional thoughts
• visualize outcomes

symptoms of overstretching:

• poor retention
• mental fatigue
• weak recent memory
• fast thoughts
• intrusive or irrelevant thoughts
• inability to shut brain down

this is called cognitive overload.

5. fast thoughts, inner voice, and intrusive thoughts

these come from overactive default mode network (dmn) + low dopamine + mental fatigue.

signs:

• thoughts jump rapidly
• random mental chatter
• irrelevant words or lines popping up
• hard to stay silent in mind
• fast inner voice
• thinking while doing other tasks
• difficulty staying present

not hallucinations — just an overloaded thinking system.

6. retention problems (not remembering what you read)

you don’t retain new information because:

• your working memory is full
• neurotransmitters are low
• pfc is fatigued
• dmn is interrupting
• dopamine dips block learning
• too much content consumption, too little consolidation

so information never converts from short-term → long-term memory.

7. why deep thinkers can be lean

not always, but common because:

• higher cognitive calorie burn
• high stress raises metabolism
• lower appetite
• irregular eating
• constant glucose use by the brain

8. in one line summary

your mind is extremely active, always thinking, analyzing, and planning — this leads to:

• pfc overload
• working memory weakness
• dopamine instability
• glucose dips
• fast thoughts
• intrusive mental noise
• poor retention
• difficulty remembering recent events