Before the body can benefit from consumed nutrients, the gastrointestinal tract has to digest and absorb the foods. Before eating, the body needs to feel hungry. However, hunger is not the same as appetite. Hunger is a physical reaction caused by hormonal and chemical changes in the body when fuel is needed. Appetite is more of a desire to eat and can be a learned response. It is one reason why individuals can eat when they are not hungry. The body comprises different hormones that regulate hunger, digestion, and appetite.

Hunger Digestion Regulating Hormones

Hunger Hormones

Hunger is the feeling when the body needs food. When the body has enough, hunger should subside. That’s because various hormones regulate hunger.

Leptin

• Leptin is a hormone secreted by adipose tissue/fat into the bloodstream.
• The more fat in the body, the higher the blood levels of leptin.
• Leptin level also increases with food intake and is higher in females than males, but overall, it lowers with age.
• Increased leptin levels trigger the hypothalamus to reduce hunger.

Ghrelin

• Ghrelin is a hormone produced by the stomach and small intestine when the stomach is empty.
• Like leptin, it also works with the hypothalamus.
• However, instead of suppressing hunger, it increases hunger.

Insulin

• The pancreas produces this hormone.
• It is mostly known for regulating blood sugar levels.
• It also suppresses hunger.

Adiponectin

• Adiponectin is a hormone secreted by fat cells.
• As body fat levels go down, this hormone goes up.
• If fat levels go up, adiponectin levels go down.

Cholecystokinin

• Cholecystokinin is a hormone produced in the small intestine during and after a meal.
• It triggers the release of bile and digestive enzymes into the small intestine.
• These suppress hunger and make the body feel full.

Peptide YY

• This hormone suppresses appetite for about 12 hours after eating.
• Made by both the large and small intestines after eating.

Glucocorticoids

• Adrenal glands make these hormones, and their primary function is to regulate inflammation and other processes, but they also impact hunger.
• A cortisol deficiency reduces appetite, but excessive amounts of glucocorticoids increase hunger.

Digestion Hormones

Digestion is coordinated and regulated by hormones.

Gastrin

• Gastrin is a hormone the stomach and the small intestine release when eating.
• Gastrin stimulates the release of hydrochloric acid and pepsinogen in the stomach to speed up digestion.
• Gastrin stimulates glucagon, which works with insulin to regulate blood sugar.

Secretin

• Secretin is a hormone made by the small intestine.
• It is secreted into the bloodstream when the acidic chyme from the stomach enters the small intestine.
• Secretin stimulates the pancreas to release bicarbonate digestive liquids into the small intestine.
• The bicarbonate neutralizes the acidity.
• Secretin acts on the stomach to trigger the production of pepsinogen to help break down proteins.

Cholecystokinin – CCK

• The small intestine makes and releases CCK into the bloodstream.
• Essential fat digestion stimulates the gallbladder to release bile into the small intestine.
• It also triggers the pancreas to release various digestive enzymes so they can break down fats, carbohydrates, and proteins.

Motilin

• The small intestine makes Motilin.
• Motilin speeds up activity in the stomach and small intestine.
• It also stimulates the stomach and pancreas to release various secretions and causes the gallbladder to contract.

Glucose – Dependent Insulinotropic Peptide – GIP

• Sometimes called a gastric inhibitory peptide.
• The small intestine makes this hormone.
• It stimulates the pancreas to release insulin and slows down stomach digestive activity.

Peptide YY and Enterogastrone

• Released by the small intestine, two more hormones slow digestion down and decrease the production of digestive secretions.

---

Chiropractic Care and Metabolism

---

References

Chandra, Rashmi, and Rodger A Liddle. “Cholecystokinin.” Current Opinion in Endocrinology, diabetes, and Obesity vol. 14,1 (2007): 63-7. doi:10.1097/MED.0b013e3280122850

Davis, Jon. “Hunger, ghrelin and the gut.” Brain Research vol. 1693, Pt B (2018): 154-158. doi:10.1016/j.brainres.2018.01.024

Gupta K, Raja A. Physiology, Gastric Inhibitory Peptide. [Updated 2022 Sep 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: www.ncbi.nlm.nih.gov/books/NBK546653/

Konturek, S J et al. “Brain-gut axis and its role in the control of food intake.” Journal of Physiology and Pharmacology: an official journal of the Polish Physiological Society vol. 55,1 Pt 2 (2004): 137-54.

Prosapio JG, Sankar P, Jialal I. Physiology, Gastrin. [Updated 2023 Apr 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: www.ncbi.nlm.nih.gov/books/NBK534822/

Rix I, Nexøe-Larsen C, Bergmann NC, et al. Glucagon Physiology. [Updated 2019 Jul 16]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: www.ncbi.nlm.nih.gov/books/NBK279127/

Suzuki, Keisuke, et al. “The role of gut hormones and the hypothalamus in appetite regulation.” Endocrine Journal vol. 57,5 (2010): 359-72. doi:10.1507/endocrine.k10e-077

Tack, Jan, et al. “The gastrointestinal tract in hunger and satiety signaling.” United European gastroenterology journal vol. 9,6 (2021): 727-734. doi:10.1002/ueg2.12097

Zanchi, Davide, et al. “The impact of gut hormones on the neural circuit of appetite and satiety: A systematic review.” Neuroscience and biobehavioral reviews vol. 80 (2017): 457-475. doi:10.1016/j.neubiorev.2017.06.013