There's a lot of buzz about the link between sugar and the circuitry in our brains. As sugar can directly affect our activation pathways, what exactly occurs when we consume sugar?
Let's start off by defining what this compound is that has such an effect on our physiological state. Sugar is a general term used to describe a class of molecules called carbohydrates. Since it's everywhere, it's important to understand what happens when sugar hits the tongue and why it behaves like a drug.
When we consume sugar, these molecules activate the sweet taste receptors (part of our taste buds), and these receptors send a signal to the brain stem. From there, it goes off into many areas of the forebrain, one of which is the cerebral cortex. Different sections of the cerebral cortex process different tastes, and this signal activates the brain's reward system (a series of electrical and chemical pathways across several different regions of the brain). That happy feeling you get after a bite of something sweet is the reward system at play. This sugar travels all the way down into the gut where there are sugar receptors as well. The major currency of our reward system is dopamine, an important neurotransmitter that can be dense in certain areas (also known as dopamine hotspots). But overactivation of this system kicks off a series of events like loss of control, craving, and increased tolerance to sugar.
What happens to our brain after eating a balanced meal?
Even with a balanced meal, dopamine levels may spike in our reward hotspots. However, if you eat that same dish consistently, dopamine levels will spike less and less, eventually leveling out. When it comes to food, the brain evolved to pay special attention to new and different tastes. This is to detect if foods has gone bad, and favor variety in our diets (which will push us to eat healthier and newer foods).
What happens if instead of the balanced meal, we eat sugar-laden food instead?
If you rarely eat sugar, the effect is similar to a balanced meal. If you eat sugar constantly, the dopamine response does not level out, and will continue to feel rewarding. In this way, sugar behaves a bit like a drug as it can attach to the same receptors in our brain as morphine does. Every time sugar is consumed, it kickstarts a domino effect in the brain that sparks a rewarding feeling. Too much too often, and things can go in overdrive.