The Digestive System As the white bread passes through your mouth, stomach, and small intestine, more amylase generated by your pancreas digests any residual starch molecules until only glucose remains. Amylase is an enzyme that breaks down starch into sugar. Your body can't store starch so it is always converted into sugar which can be used as energy. As soon as you eat bread, potatoes, or other starches, your body begins to digest them right away. The more rapidly you eat food, the faster your body will digest it and use the nutrients. When you eat slowly, your body has time to absorb the nutrients from your food rather than just using up its energy on digestion. As mentioned, starch is a major component of wheat flour, which means that if you eat a lot of white bread, pasta, and other products made with flour you're going to end up eating a lot of starch. Starch is stored in the body as glucose, which is our blood's main fuel. So if you eat a lot of starch, then your body will have to make more insulin to pull some of this glucose out of your bloodstream and store it in your muscles and liver for later use. This explains why people who eat a lot of starch often feel tired and drained of energy- they are actually burning the energy they consume!