|10-16-2006, 08:02 PM||#1|
I came across this in the md.
"Basically, a diet high in fat activates the lipolytic (fat burning) enzymes in your body
and decreases the activity of the lipogenic (fat producing) enzymes. Dietary free fatty
acids and triglycerides become the body's main energy source. The triglycerides are
broken down to free fatty acids and some of the fatty acids are metabolized to
ketones, which in turn can be used for energy by body cells. The use of ketones for
energy is especially important to the brain that can only use glucose and ketones for
energy. In short, the free fatty acids and ketones take the place of glucose and the
triglycerides act like glycogen"
I always thought that the body could convert fat to glycogen. My question is does the body always use tryglicerides directly in the absense of glycogen or are there situations where it will convert fat to glycogen?
|10-17-2006, 09:02 AM||#3|
where it will convert fat to glycogen?
The body can convert glycerol to glucose but it prefers to use amino acids for gluconeogenesis.
"Oxidation of fatty acids yields enormous amounts of energy on a molar basis, however, the carbons of the fatty acids cannot be utilized for net synthesis of glucose. The two carbon unit of acetyl-CoA derived from b-oxidation of fatty acids can be incorporated into the TCA cycle, however, during the TCA cycle two carbons are lost as CO2. Thus, explaining why fatty acids do not undergo net conversion to carbohydrate.
The glycerol backbone of lipids can be used for gluconeogenesis. This requires phosphorylation to glycerol-3-phosphate by glycerol kinase and dehydrogenation to dihydroxyacetone phosphate (DHAP) by glyceraldehyde-3-phosphate dehydrogenase(G3PDH). The G3PDH reaction is the same as that used in the transport of cytosolic reducing equivalents into the mitochondrion for use in oxidative phosphorylation. This transport pathway is called the glycerol-phosphate shuttle. The glycerol backbone of adipose tissue stored triacylgycerols is ensured of being used as a gluconeogenic substrate since adipose cells lack glycerol kinase. In fact adipocytes require a basal level of glycolysis in order to provide them with DHAP as an intermediate in the synthesis of triacyglycerols."
(Message edited by cjackson on October 17, 2006)
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