Your body runs on sugar — glucose to be precise. Glucose comes from the Greek word glukos which means sweet. Glucose fuels the cells that make up our body — including brain cells (neurons).
Dopamine "hits" from eating sugar
On an evolutionary basis, our primitive ancestors were scavengers. Sugary foods are excellent sources of energy, so we have evolved to find sweet foods particularly pleasurable. Foods with unpleasant, bitter and sour tastes can be unripe, poisonous or rotting — causing sickness.
So to maximize our survival as a species, we have an innate brain system that makes us like sweet foods since they're a great source of energy to fuel our bodies.
When we eat sweet foods the brain's reward system — called the mesolimbic dopamine system — gets activated. Dopamine is a brain chemical released by neurons and can signal that an event was positive. When the reward system fires, it reinforces behaviors — making it more likely for us to carry out these actions again.
Dopamine "hits" from eating sugar promote rapid learning to preferentially find more of these foods.
Our environment today is abundant with sweet, energy rich foods. We no longer have to forage for these special sugary foods — they are available everywhere. Unfortunately, our brain is still functionally very similar to our ancestors, and it really likes sugar. So what happens in the brain when we excessively consume sugar?
In the case of sweet foods, this means we need to eat more to get the same rewarding feeling — a classic feature of addiction.
Food addiction is a controversial subject among scientists and clinicians. While it is true that you can become physically dependent on certain drugs, it is debated whether you can be addicted to food when you need it for basic survival.
The brain wants sugar, then more sugar
Regardless of our need for food to power our bodies, many people experience food cravings, particularly when stressed, hungry or just faced with an alluring display of cakes in a coffee shop.
To resist cravings, we need to inhibit our natural response to indulge in these tasty foods. A network of inhibitory neurons is critical for controlling behavior. These neurons are concentrated in the prefrontal cortex — a key area of the brain involved in decision-making, impulse control and delaying gratification.
Importantly, the brain's neuroplasticity capabilities allow it to reset to an extent following cutting down on dietary sugar, and physical exercise can augment this process. Foods rich in omega-3 fats (found in fish oil, nuts and seeds) are also neuroprotective and can boost brain chemicals needed to form new neurons.