Your Brain: The Missing Manual

Brain Fuel

Glucose—simple sugar—is the raw fuel that powers your brain. Unlike the muscles in your body, your brain can't tap the energy reserves in your body fat. (So thinking hard might tire you out, but it won't slim you down.)

Figure 2-1. Your Friend: The Glucose Molecule

Studies consistently find that very low glucose levels weaken the brain's ability to concentrate, remember, and pay attention. Some anthropologists even believe that our early ancestors kicked their brains into high gear when they discovered starchy tubers, a rich source of carbohydrates that can be readily broken down into sugar. (Potatoes, turnips, cassava and many other root vegetables fall into this category.) Although there's no concrete proof, the idea certainly gives French fry fans some serious food for thought.

Under normal conditions, the brain always gets the trickle of sugar it needs to stay functioning. However, certain drugs and diseases can bring on hypoglycemia, a condition in which even the brain's bare minimum sugar requirements can't be met. (For example, hypoglycemia is a possible side-effect of the blood-lowering medication taken by diabetes patients.) If this happens to you and your brain is deprived of sugar, you're likely to experience weakness, confusion, dizziness, and ultimately unconsciousness.

In other words, nothing craves glucose like a working brain.

Raw Sugar at Work

Now that ...