The following foods are allowed in a clear liquid diet: Water (plain, carbonated or flavored) Fruit juices without pulp, such as apple or white grape. Fruit-flavored beverages, such as fruit punch or lemonade. Carbonated drinks, including dark sodas (cola and root beer) Gelatin.
Your body has a mechanism and set of enzymes for digesting the carbs, protein and fat molecules in your food. Chemical digestion occurs in several steps beginning in the mouth and ending with absorption in the small intestinal cells.
Though carbohydrate digestion starts in the mouth, most of the actual work takes place in the small intestine. With the work of three different enzymes, carbs get broken down from polysaccharides to shorter glucose chains and disaccharides. Enzymes in the outer membrane of the intestinal cell perform the final dismantling of the carbohydrates. These enzymes are maltase, which breaks down maltose into glucose; sucrase, which breaks down sucrose into glucose and fructose; and lactase, which breaks down lactose into glucose and galactose.