The most important part here is that we are in full control of how we release glucose to our blood and our brains. Certain foods release glucose quickly, whilst others do so more slowly, yet sustainably. For your brain researcher Leigh Gibson found this to be optimal:
“The brain works best with about 25 grams of glucose circulating in the blood stream — about the amount found in a banana.”
And this is the tricky part: the way you can get those 25 grams of glucose into your blood stream is pretty easy. You can eat a donut. Or you can eat a small bowl of oats. There is virtually no difference in the very short term for your brain activity.
Over the stretch of a normal 8 hour day however, the differences are spectacular. After eating the donut, we will release glucose into our blood very quickly. We will have about 20 minutes of alertness. Then our glucose level will drop rapidly, leaving you unfocused and easy to distract. It’s like putting the foot down on the gas pedal until you’ve used all your fuel.
The oats on the other hand will release their sugar as glucose much slower. This means we will have a steady glucose level, better focus and attention levels. Another important factor are your Leptin levels. Leptin will signal to your brain how full you are. If you are now guessing that a donut won’t signal your brain to be full for a long time, whilst oats will, well, you are right: