Fasting & biochemical processes & ketone bodies

[blazinfury]

If a person is fasting, what biochemical processes occur to generate energy to get the person through this period. Since the body is low on glucose, gluconeogenesis would occur to synthesize more glucose so that it can enter glycolysis and be broken down. The body would also undergo fatty acid synthesis on the mitochondria which would enter the Krebs cycle to generate energy. Proteins would be broken down into amino acids and those amino acids would enter Krebs as well?

 

If all of this happens, then why do Ketone bodies form and what is their purpose?

[BabcockHall]

There would not be any fatty acid synthesis, but rather fatty acids would be catabolized, some to carbon dioxide and some into ketone bodies. Some of the TAG stores in adipose and elsewhere would be turned into ketone bodies in the mitochondria of liver. These are water soluble, and heart muscle would be one tissue that would use them for energy. Some portion of the proteins would also become ketone bodies, because some amino acids are entirely ketogenic.

[Consistency]

If all of this happens, then why do Ketone bodies form and what is their purpose?

 

Fuel for the brain when glucose isn't present. Brain can't produce its own ketone bodies.

 

Ketosis is survival metabolism.

Edited February 13, 2013 by Consistency