The Greedy Three Pound Organ
Your brain weighs almost nothing but consumes 20 percent of every calorie you eat.
The human brain is a biological power vacuum. Despite making up only 2% of your body weight, it demands a constant 20% of your total energy intake just to keep the lights on.
This energy doesn't go toward complex math or writing poetry. Most of it is used for "housekeeping"—shuttling sodium and potassium ions across cell membranes to maintain an electrical charge.
Because the brain has no way to store this energy, a ten-second interruption in blood flow causes immediate unconsciousness. If you stop eating, your body will shrink your muscles and organs to feed the brain first.
Even while you sleep, your neurons are firing with roughly the same intensity as they do during the day. This raises a strange reality: a person sitting still and thinking hard can burn more glucose than a person walking slowly. This high-octane lifestyle is likely why newborn babies spend nearly 65% of their total body energy on brain development alone.
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