It is inhibited by phosphorylation. Glycogen phosphorylase is the major enzyme required for glycogen breakdown and it is activated by glucagon through a phosphorylation regulatory mechanism. Triglycerides have the higher stored energy potential per gram because fats are essentially unhydrated as compared to glycogen which is very hydrated. Name a physiological condition that causes this. Excess acetyl CoA is converted to ketone bodies when OAA levels are limiting but energy requirements are high.
Brain cells prefer glucose as a carbon source.
No, because animals cannot convert acetyl CoA to pyruvate. Note that the glycerol component of triglycerides does contribute in a minor way to carbohydrate production, but the fast majority of stored energy in fatty acids cannot be utilized as a source of glucose. Animals cannot convert fat to carbohydrates. Orlistat is a new anti-obesity drug that has been released onto the market. It binds to and inhibits pancreatic lipase activity in the intestine.