By Robert A. Shaffer M.D., Medical Director
Denise Biro, Weight Loss Coordinator
Shaffer
Weight Loss Center at Gastroenterology Associates, N.A.P.C.
Our body naturally tells us when to eat
and when to stop by hormones and neurons: ghrelen, neuropeptied Y, cholecystokinin,
peptide YY, insulin, leptin and melanocortin. Problems begin when we do not
listen to the signaling of our body. As we continue to consume more calories
than needed without expending them, we start to develop excess fat and over
time this can lead to health problems due to an erroneous message sent by the
hormone leptin. Our appetite; hunger and satiety are regulated by the endocrine
system that communicates with the hypothalamus and is controlled by a negative
feedback system which can be disrupted by an improper diet leading to obesity.
The stomach secretes a hunger hormone that
sends a message to the brain to tell us it is time to eat. When our stomach is
empty it produces the hormone ghrelin. Ghrelin sends a message from the epithelial
cells of the the gastric fundus to the arcuate nucleus of the hypothalamous;
the center for appetite regulation in the brain. Ghrelin then stimulates the neuropeptide Y
secreting neurons in the brain to increase hunger.
Upon consuming food our stomach stretches
and hormones start communicating with the appetite control center to signal
satiety. Ghrelin concentrations decrease due to the release of the hormone cholecystokinin
(CCK) from the enteroendocrine cells of the small intestine. Cholecystokinin
then works together with another hormone called Peptide YY from the large and
small intestine in a negative feedback cycle to control the appetite over a
period of time.
Another
hormone that controls our appetite is insulin. Insulin is released from the
beta cells of the pancreas to indicate that your body is metabolizing and not
to consume anymore food. Insulin
regulates our fat stores by stimulating adiposytes (fat cells) to take up
glucose and store as fat to use as energy at a later time. As we eat, adiposcytes are stimulated to
secrete leptin which stimulates melanocortin secretion in the arcuate nucleus
of the hypothalamus signaling satiety; preventing the continued release of
neuropeptide Y.
Improper diet can lead the accumulation of
excess adipose tissue and cause disruption in signaling of leptin secretion. A person with a higher body fat mass will
secrete an excess of leptin by the adipose cells. Here is the problem: over a
long period of time this excess secretion of leptin can cause a disturbance in
our negative feedback system. This causes our feedback system to become unresponsive
to leptin or to have a receptor defect on the target cells in the hypothalamus.
This disruptive signal of leptin signaling
sends a message to the brain that we are hungry even after we just ate a big
meal. This could be a contributing
factor that leads to obesity and other health disorders like fatty liver and
insulin resistance. The best way to these issues is to follow a healthy
nutrition plan and exercise. For more information on nutrition, exercise and
diet please call 205-397-1448.
Shaffer Weight Loss Center at
Gastroenterology Associates, N.A.P.C.
100
Pilot Medical Drive
Suite 250
Birmingham
AL 35235
(p) 205 397 1448
(w) gastrodocs.info
(e) weightloss@ganapc.net
facebook.com/ shafferweightlosscenter.com
Resources:
http://www.ncbi.nlm.nih.gov/books/NBK22251/
http://www.jci.org/articles/view/36284
http://www.cdc.gov/pcd/issues/2009/jul/pdf/09_0011.pdf
http://circres.ahajournals.org/content/101/6/545.full
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