Learned behaviors
Our brains are basically seeking pleasure, therefore we are quick to learn how to enjoy food. So once you learn that chocolates and burgers can bring pleasure it's really hard to convince yourself to not eat them all the time. They are, in reality far more satisfying than fruits or salad. The way we think about pleasure is not correlated with how healthy the food is. It's only interested in satisfaction and pleasure.
Food industry invests many resources into finding ways to attract more customers. They also wish to know ways to satisfy our pleasure-seeking brains and create food that is so attractive that you are compelled to take it in. However, there's another aspect of the coin. Understanding the intricate relationship between food, pleasure and health can allow us to create food that gives us the pleasure we crave without contributing to obesity.