The "liver enzymes", AST, ALT, and to a lesser degree of specificity alk-phosphate are created and stay within the cells of the liver, which are called hepatocytes.
Liver enzymes are spilled out and taken up into the blood stream when a hepatocyte dies and the cell membrane bursts.
So, higher levels of the enzymes indcicate that greater numbers of cells have died. There is always some amount of cell death and new ones are made.
Inflammation of the liver is called hepatitis. Often, when the liver is inflamed, cell death rate is higher and therefore the enzyme level in the blood will be higher.
Excessive carbohydrate intake does stress the liver. When you have more sugar in the blood than the body needs, it converts it to glycogen and stores it in the liver. Once glycogen stores are maximized, a much less desirable condition can occur where the hepatocytes get filled with fat. That causes what is called stetohepatitis and is a common cause of elevated AST and ALT in people who otherwise have no liver disease.