Appetite Hormones

Have you ever wondered why you continue to be hungry when you may have just eaten?  It could have something to do with the hormones in your body and their effect on the brain.  The following is a little scientific but thought the information would be good to share.  In another post, I will plainly explain the role of some of these hormones and how they affect our daily lives.

"Appetite control is highly complex and involves neurotransmitters in the brain and hormones in both the adipose tissue and the gut. The future of weight management may relate to an understanding of the hormones that affect satiety. This is a brief summary of some of the key hormonal players in appetite regulation.

Ghrelin
Ghrelin is a short-term factor secreted by the stomach just before an expected meal. It acts on the hypothalamus to stimulate hunger.

Glucagon-like peptide 1 (GLP-1)
This is released from the cells of the gastrointestinal (GI) tract postprandially in proportion to the calories ingested. GLP-1 decreases food intake, increases the expression of the insulin gene, and increases the secretion of insulin.

Insulin
Insulin acts in the central nervous system and periphery nervous system to regulate food intake. Impaired insulin activity may lead to impaired thermogenesis.

Leptin
This hormone is produced by adipose tissue. It binds to the ventral medial nucleus of the hypothalamus (known at the “satiety center”), which signals the brain to stop eating. In obesity, it loses the ability to inhibit energy intake or to increase energy expenditure.

Norepinephrine and cortisol
These stress hormones are released by the sympathetic nervous system. Norepinephrine helps activate the sympathetic nervous system in the “fight-or-flight” response.Cortisol helps to restore homeostasis after stress and acts as a physiological antagonist to insulin.

Pancreatic polypeptide (PP)
PP is released by the pancreas into the circulation after a meal in proportion to the calories ingested. The role of PP in regulation of energy balance is unclear, although studies have shown it reduces food intake when administered to rodents and humans.

Peptide YY (PYY)
PYY is secreted by endocrine cells lining the small bowel and colon in response to food. PYY induces satiety."

References and recommended readings

RD411

Chaudhri OB, Wynee K, Bloom SR. Can gut hormones control appetite and prevent obesity? Diabetes Care [serial online]. 2008;31(suppl 2):S284-S289.
Available at: http://care.diabetesjournals.org/content/31/Supplement_2/S284.full.pdf+html.
Accessed March 1, 2011.

Mahan LK, Escott-Stump S. Krause’s Food and Nutrition Therapy. 12th ed. St Louis, MO: Saunders/Elsevier; 2008.
Simpson KA, Martin NM, Bloom SR. Hypothalamic regulation of appetite: gut hormones.
Available at: http://www.medscape.com/viewarticle/581204_6.
Accessed March 1, 2011.




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