Glucose paradox is a theory formulated by biochemist J. D. McGarry and his research associates. It is a theory that demonstrates the importance of lactic acid in carbohydrate metabolism. The paradox is that the large amount of glycogen (10%) in the liver cannot be explained by its relatively minimal glucose absorption.
After the digestion of carbohydrates and their entering the circulatory system in the form of glucose (blood sugar), some glucose will be absorbed directly into the muscle tissue and will be converted into lactic acid in the anaerobic energy system rather than going directly to the liver and being converted into glycogen. This is true especially in situations of energy depletion and exercise.
The lactate is then taken to and converted by the liver into the building blocks for liver glycogen. Much of the body's liver glycogen is produced indirectly from lactate rather than directly from glucose in the blood.
Under normal physiological conditions, glucose is a poor precursor for glycogen and fatty acid and utilization by the liver is limited.