Serotonin Serotonin is a neurotransmitter that effects how pleasant you feel. Long serotonin levels can lead to depression. Low serotonin levels can stimulate your appetite so that you medicate yourself through eating carbohydrates. Carbohydrates have a tendency to elevate serotonin levels. There are nutrients that can bring your serotonin levels up to normal and reduce your appetite. This is another factor our consultants consider when monitoring your weight control situation.