# Hunger --- **Hunger** is a non-specific, physiological drive to [[nutrition|eat]]. It is not the same thing as an [[appetite]], which is the *psychological* drive to eat. **Satiety** is the feeling of fullness after eating. Different types of foods create weaker or stronger level of satiety, depending on what they are made up of. High-fat foods have a higher satiety value than high-carb foods, and the more fiber or water a food has the more it stretches the [[stomach]] and [[small intestine]], and so sends stronger satiety signals. For the same reason, sold or semi-solid foods produce more satiety than liquids do—think about how a smoothie is way easier to drink than all the individual ingredients whole would be. You'd fill up! ## Signals to And From the Hypothalamus Sensations of hunger (and satiety) originate in the [[hypothalamus]] region of the brain. It monitors the hormone levels and signals from nerve cells lining the mouth and esophagus and either activates it's **"feeding center**" or the **"satiety center"** depending what it detects. ## The Hormones of Hunger The main [[hormone|hormones]] of hunger and satiety are **insulin** and **glucagon**, **ghrelin** and **cholecystokinin**, and **leptin**. **[[Insulin]] and [[glucagon]]** are hormones that are produced based on the presence or absence of [[glucose]]—insulin is released when there is high levels of blood glucose, and glucagon is released when there are low levels. The presence of glucagon actually sends signals for the [[hypothalamus]] to make us hungry. **[[Ghrelin]] and [[cholecystokinin]]** are hormones that are produced based on the presence or absence of food in the [[digestive system]]. Ghrelin levels slowly increase after the last time you ate, and high levels of it trigger the [[hypothalamus|feeding center]] of the hypothalamus. The opposing hormone to ghrelin is cholecystokinin, which is produced when food enters the [[small intestine]], and the presence of that triggers the [[hypothalamus#Hunger|satiety center]] of the hypothalamus. **[[Leptin]]** is a hormone that regulates huger in the long term. It is produced by [[adipose tissue]], so the more adipose we have the more leptin is produced. Individuals with a lot of adipose tissue can develop a resistance to leptin, causing them to be insensitive to the hunger-suppressing effects. ___