When you are faced with food that you are not used to eating, or in larger quantites that you usually allow yourself to eat, you go into your sympathetic nervous system -- that's the fight or flight one. Food doesn't taste that good when you are stressed about it! But, if you continue to force yourself to eat, your brain learns that the food is not a threat, and in time, you remain calm when eating. This is what leads to the neural rewiring of your brain that these foods are not a threat to you.