Methylation is the addition of a single carbon and three hydrogen atoms (called a methyl group) to another molecule. The removal of a methyl group is called demethylation. The addition or removal of a methyl group to a particular molecule essentially acts as on/off switch for cellular processes. It controls many processes including your stress response, histamine production, how your body makes energy from food, detoxification and brain chemistry. If your methylation cycle is over or under active, symptoms will result. Identification of these imbalances may result in lifelong changes e.g. improved mood and/or elimination of fibromyalgia symptoms.