There are two neurobiological mechanisms that make us eat, one driven by need and the other by desire.
Based in the brain’s hypothalamus, the need to eat is sparked by metabolic messages from the digestive system.
The desire to eat, however, is controlled by higher brain centres such as the dopamine reward system. When food with high calories counts is taken in, the nucleus accumbens part of the brain is flooded with dopamine, thus increasing the eater’s pleasure.
Often the dopamine rewards system overrides the hypothalamus, which is why we carry on eating tasty food, even when we’re not hungry.