The changes that occur in the body during a fast depend on the length of the continuous fast. The body enters into a fasting state eight hours or so after the last meal, when the gut finishes absorbing nutrients from the food. In the normal state, body glucose, which is stored in the liver and muscles in the form of glycogen, is the body’s main source of energy. During a fast, this store of glucose is used up first to provide energy. Later in the fast, once the glucose runs out, fat becomes the next source of energy for the body. With a prolonged fast of many days or weeks, the body starts using protein for energy. This is the technical description of what is commonly known as ‘starvation’. It is clearly unhealthy. It involves protein being released by the breakdown of muscle, which is why people who starve look very thin and become very weak. However, you are unlikely to reach the starvation stage during Ramadan because the fast is broken daily.