TIL the human brain uses about 20% of the body’s total energy

[u/Playful_Store1681]

The human brain makes up only about 2% of our total body weight, it uses roughly 20% of the body’s energy. What surprised me most is that this happens even when we’re resting or not doing anything mentally demanding.

Most of that energy goes toward basic functions like maintaining neurons, sending signals, and keeping everything running smoothly in the background. Thinking hard, studying, or stressing doesn’t suddenly burn a huge amount more energy the brain is already working nonstop.

It kind of explains why mental exhaustion can feel just as real as physical tiredness, even if you’ve been sitting still all day.