Wednesday, January 27, 2010
Glyceroneogenesis, and Other Reasons for Fat Storage on Zero Carb
This week I have an extra set of responsibilities in real life and have had a hard time finding time for a new blog post. Fortunately I recently learned of an excellent article by LynMarie Daye, Is the Fable of Unfettered Fat Burning Derailing Your Low Carb Diet?
The author explains in clear and well-referenced terms how the body is able to store fat in the relative absence of insulin. As she says, only type-1 diabetics have a total absence of insulin, and it is true that they cannot store fat. However, the rest of us have a low baseline level of insulin at all times, and in that situation, Acylation Stimulating Protein is able to promote fat storage even when blood insulin levels remain low.
It is also true that fat storage requires the presence glycerol 3-phosphate to form the backbone of the triglyceride molecule. However, simply refraining from eating carbs is not sufficient to stop the synthesis of glycerol 3-phosphate. Even in a state of prolonged fasting, the body is able to use its own muscle protein to synthesize glycerol 3-phosphate. This metabolic pathway is called glyceroneogenesis, and it is illustrated in the figure above.
If you have ever wondered how it is possible to eat no carbs whatsoever and still gain weight, LynMarie Daye provides a thorough treatment of the issue. I highly recommend her article.