Drinking only water without eating the body will become lethargic, hypoglycemia and so on. 1. Wasting: mainly due to the body’s fat or protein consumption. The body’s energy mainly comes from glucose, when the body activities need to consume a lot of energy. The body’s consumption of energy is in the order of glucose, fat and protein. Fats and proteins are important substances that make up the body’s tissues, and when they are gradually consumed, the body will show a state of emaciation. 2. Hypoglycemia: It is mainly manifested as cold sweat, fainting, and darkness in front of the eyes. Drinking only water is not able to provide glucose needed for human activity, therefore, the source of glucose decreases and consumption increases, resulting in the manifestation of hypoglycemia. If any of these conditions occur, please seek medical attention. People can not just drink water without eating, only to maintain a balanced diet, the body’s physiological functions can be in a normal state.