Fat, salt and sugar make stuff taste 'good' because these were rare resources when humanity was young. This is the simple recipy of McDonalds and it is true for

Fat, salt and sugar make stuff taste 'good' because these were rare resources when humanity was young. This is the simple recipy of McDonalds and it is true for all food, including healthy stuff. If McDonalds were to use less fat and sugar they would have to use more delicate and more expensive ingredients to keep it yummie. Sadly, many people care more for simple and cheap (i.e. fat and sugar) than delicate and healthy (i.e. unprocessed food). Even though every doctor, cook and common sense would advise otherwise.