What percentage of our total metabolic energy is used by the human brain?

What percentage of our total metabolic energy is used by the human brain?

• A. 16%.
• B. 10%.
• C. 25%.
• D. 5%.

Answer: (A)

The brain’s energy demand is disproportionately high relative to its size. Even though it weighs only about 2% of the body, it uses a large portion of the body's energy because neurons constantly maintain membrane potentials and transmit signals. In adults, this energy use is typically around one-fifth of total resting energy expenditure, so 16% is the closest representation of that figure among the options. Values like 10% or 5% underestimate how costly neural activity is, while 25% would overshoot the usual estimate for resting conditions.

The brain’s energy demand is disproportionately high relative to its size. Even though it weighs only about 2% of the body, it uses a large portion of the body's energy because neurons constantly maintain membrane potentials and transmit signals. In adults, this energy use is typically around one-fifth of total resting energy expenditure, so 16% is the closest representation of that figure among the options. Values like 10% or 5% underestimate how costly neural activity is, while 25% would overshoot the usual estimate for resting conditions.