Yesterday, some of my classmates and I were having a post-exams dinner at Gerry’s Libis when the question of why we were all drained, tired, and famished after the exams. I mentioned that I read somewhere that the brain consumes a lot of energy. But how much exactly I didn’t know. So I did a quick look up and found the following (from Power Of A Human Brain):
The brain makes up 2% of a person’s weight. Despite this, even at rest, the brain consumes 20% of the body’s energy. The brain consumes energy at 10 times the rate of the rest of the body per gram of tissue. The average power consumption of a typical adult is 100 Watts and the brain consumes 20% of this making the power of the brain 20 W.Glucose is the main energy source for the brain. As the size and complexity of the brain increases, energy requirements increase.
The human brain is one of the most energy hungry organs in the body thereby increasing its vulnerability. If the energy supply is cut off for 10 minutes, there is permanent brain damage. There is no other organ nearly as sensitive to changes in its energy supply.
Incidentally, the question why some people get chubby at MBA also popped up. My theory is that people usually eat a lot after brainwork. Thus they tend to eat more but the energy is no longer needed so it gets stored as fat. The solution, I think, would be to eat a bit before doing anything majorly cerebral :D