A person can create a false fever by causing a thermometer to read at a higher temperature after running it under hot water. Another method is to drink warm water to elevate body temperature before sticking the thermometer in the mouth. Body temperature can also be raised by holding a bar of lye soap under an armpit for at least three minutes before a thermometer reading, according to Reference.com.
Peter Nalin, director of the family practice residency program and an associate professor of clinical family medicine at Indiana University, notes in an article for Scientific American that a fever is the result of body temperature becoming elevated past the normal range. When one gets a fever, it is the body's way of responding to the stimulation of the immune system. Often, fever is the result of an attack on the system by an infectious bacteria or virus. As these biological invaders spread throughout the body, the immune system kicks into high gear to keep the infection from dominating.
According to Nalin, the hypothalamus acts as the body's natural thermostat and is located at the base of the brain. This gland controls the level of heat generated by a fever. A person with a fever is advised to eat less until the fever subsides. Eating may stress the digestive system too much, which can trigger more serious problems.