Insulin has a huge role in regulating dopamine. People initially like carbohydrates because they feel so much pleasure from them. It stimulates dopamine at first, but you start developing insulin resistance the more you do it chronically. So that means that insulin is unavailable to you. There are a lot of different receptors for insulin in the brain. For example, you're going to create a lowered amount of dopamine. From a food angle, if you have a history of consuming many carbohydrates, your dopamine might be pretty low because you have insulin resistance.