Appetite can be affected by various parameters, which are complemented by the brain, and most importantly, hypothalamus. The incoming messages to the hypothalamus include: afferent nerves, hormones and metabolites.
The messages from the vagus nerve transfer information from the viscera (for instance distention of the intestines). Hormonal messages include: leptin, insulin, cortisol and intestinal peptides, which are transferred to the brain through the direct function of hypothalamic control center or the vagus nerve. Metabolites such as glucose can affect appetite, in a way that a drop in blood glucose stimulates appetite; however, glucose is not ordinarily considered a major regulator of appetite. The above-mentioned messages cause release of various peptides from the hypothalamus. It seems that physiologic and cultural parameters also play a role in the final manifestations of appetite.
Based on historical evidence, tarragon has been used to increase appetite, its mechanism having been explained as taking part in insulin signaling process.Tarragon is known as a general stimulant and digestive, appetizer and alleviator of hiccups. The essential oil of tarragon stimulates appetite.