Before you get all necessary substances from nutrients you eat, your gastrointestinal system needs to absorb and digest all the products you consume. But before you have some meal, you feel hungry as your body needs food.
When you have consumed enough foods and gained proteins, carbohydrates, fats and other substances, you normally do not feel hungry. That is why the following hormones regulate this feeling.
1. Leptin. Adipose tissue (fat) secrets it into the bloodstream. The more fat in the body, the higher the level of this hormone. This level is also higher in women than in men, it is increased when you consume food and decreased as the person is getting older. It alleviates hunger by triggering hypothalamus.
2. Adiponectin. Fat cells secret this hormone. When you get some fat, the hormone level goes down and, conversely, when your body gains not enough fat, the hormone level is higher.
3. Ghrelin. When you need to have some food and the stomach is empty, your small intestine and stomach produces ghrelin. It triggers hypothalamus too but is does not suppress hunger but increases this.
4. Cholecystokinin. When you have a meal and just after it your small intestine produces this hormone. Due to this, digestive enzymes and bile are released into the small intestine suppressing hunger.
5. Insulin. It is produced in the pancreas. This hormone regulates the blood sugar level and alleviates hunger.
6. Peptide YY. This hormone is produced in small and large intestines suppressing your appetite for almost 12 hours after having a meal.
7. Glucocorticoids. Adremal glands secret these hormones, the main function of which is to reduce inflammation but they also influence the feeling of hunger.
Difference between Hunger and Appetite
Hunger is often confused with appetite but it is not the same. When your body undergoes some chemical changes because you need more food, you feel hunger. Appetite is a more psychological condition, because of which you can eat much more than you need when you even do not feel hungry.
When you consume food, the following hormones regulate the digestion:
1. Gastrin. When you have some meal, your stomach and small intestine release this hormone that normalizes the level of hydrochloric acid and pepsinogen released in your stomach. Moreover, it improves the digestion.
2. Secretin. When the small intestine gets the acidic chyme from the stomach, it produces secretin and secrets it into the bloodstream. Secretin makes the pancreas let digestive juices that are rich in bicarbonate enter the small intestine. Bicarbonate in its turn counterbalances the chyme acidity. This hormone makes your stomach produce pepsinogen to split proteins and slows down the digestive process in the stomach and in the first part of the small intestine.
3. Cholecystokinin. This hormone is released by your small intestine into the bloodstream. It helps digest fat stimulating the gallbladder to let bile enter the small intestine. Because of this hormone the pancreas also releases its digestive enzymes into the small intestine and they split carbs, proteins and fats.
4. Motilin. It is produced by the small intestine too speeding up the activity in this and in stomach. Due to this, the stomach and the pancreas produce different secretions contracting the gallbladder.
5. Glucose-dependent insulinotropic peptide. The small intestine makes this hormone that makes the pancreas produce insulin and reduces the stomach activity.