How Sugar Affects the Brain

How many people do you know who love desserts? Or candy? Or soft drinks? 
Why do people love sugary foods and drinks so much? Why do most of us not have the same love for, say, broccoli? The answer lies in your brain!

What is sugar?

Sugar is a class of molecules called carbohydrates. It appears in all kinds of food and drinks. It has many different names: sucrose, fructose, maltose, and dextrose, just to name a few. Check the labels in your kitchen cupboards. How many foods there have at least one of these ingredients?

You might be surprised to learn that sugar isn’t just in sweets! When you look through your cupboards, you might notice it in sauces and various snacks as well.

What happens in your brain when you eat sugar?

When you consume something that contains sugar, the sugars activate your sweet-taste receptors. They’re on your taste buds, which are on your tongue.

These receptors send a signal to a part of your brain called the forebrain, which is mostly comprised of the cerebrum. The forebrain then signals to many other parts, including your cerebral cortex. The cerebral cortex is the outer layer of the cerebrum.

Your cerebral cortex has many different jobs. One of them is processing sensory information. So when your sweet-taste receptors activate, your cerebral cortex gets the signal. It understands that you’re tasting something sweet. 

But that’s not all that activates. Your brain’s reward system also gets the signal. This reward system is a network of chemical pathways spanning your whole brain. 

Dr. Nicole Avena is a neuroscientist who studies nutrition and addiction. According to her, the reward system’s job is to answer the question, “Should I do that again?” That wonderful feeling you get when you eat sweets is your reward system’s way of saying, “Yes, do it again!”

Did you know?

Your brain’s reward system activates for all kinds of different reasons unrelated to food. It may activate when you hang out with your friends or a crush. It also plays a big role in addictions to things like drugs, gambling, and video games.

Sometimes, this reward system gets overactivated. In that case, you start to get cravings. Your tolerance to the substance you crave goes up. That means you need more of it to get that same sense of pleasure.

What is dopamine?

Dr. Avena describes dopamine as “the currency of our reward system.” Dopamine is a neurotransmitter. Dopamine receptors are all over your brain. But there are large clusters of them along your reward pathway.

Addictive substances tend to activate those receptors. That’s how addiction happens.

Many drugs cause these centres to become activated. Can you guess what other substance does this? That’s right - sugar! 

A delicious, healthy meal can spike dopamine levels, too. But if you eat the same meal over and over again, you’ll get less and less of a dopamine rush. That’s because your brain has evolved to notice new or different tastes. Your ancestors did not have best-before labels on their food. So they needed to be able to notice if their food had gone bad. Also, your ancestors evolved to eat a wide variety of food. The wider the variety, the more likely they were getting all of the nutrients they needed.

So what happens if you eat too much sugar?

There are also sugar receptors in your gut. So when you ingest something sugary, the receptors there are activated, too. They signal to your brain that your body should produce more insulin. Insulin is a hormone that regulates the amount of glucose (sugar) in your blood. The more sugar you eat, the more insulin your body needs to help regulate it.

Eating a little sugar now and then won’t necessarily hurt you. But if you eat too much sugar, your dopamine response will not level out. You’ll crave sugar, you’ll need more and more of it, and eventually you might become addicted. So do with sugar what you do with all the good things in life: enjoy it in moderation!