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Why does the Brain use so Much Energy?

Why does the Brain use so Much Energy?

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Why does the Brain use so Much Energy?

fatigue mental energy

The brain uses a whopping 20% of our body’s energy, yet weighs a tiny 2% of our body weight.  The brain and body are fine-tuned for energy efficiency. Our brain has evolved to target simplicity and minimal energy strategies. It likes to save energy where possible, which explains boredom and fatigue when doing one activity for a long time.

Although we often reach for a sugary snack when we’re tired, it’s a touch misleading to think that we get tired because of a lack of glucose in the brain. Though that may be true in intense, short muscle workouts, common knowledge from endurance racing tell us that the body has an incredible amount of energy at its disposal. When lifting heavy weights, our muscles quickly run out of ATP, most of which can be replaced in around 30 seconds. With endurance exercise, our muscles can replenish the ATP quickly enough that we can continue without stopping. The brain, it would seem, is more like the endurance athlete and, as we will see in the diet hacks, it has an emergency backup supply called phosphocreatine, just in case.

The brain is always on and operating at a very high level, whether we are resting with our eyes shut, admiring a beautiful vista, or solving complex equations. Researcher David Atwell and his colleagues from University College London, have shown that there is only a 6% increase in energy consumption to activate conscious perception.

Each brain cell is always in one of two modes, excited or inhibited. Both states require a lot of energy. Imagine holding back a crowd of people trying to open a door – it takes energy. Imagine being in the crowd trying to push the door open – that also takes energy. That, in essence, is how the brain works.


Excerpt from the book New Energized You. Want the fast track to more energy and vitality in your life? Get your copy now!