The effects of fasting on core temperature, blood glucose and body and organ weights in rats

Male Wistar rats of about 300 g body weight were fasted from 1 to 7 d. They were weighed and had their temperature taken daily. At the end of the experimental period, they were anaesthetized and blood was taken for measurement of the glucose content. The animals were killed and various organs were taken and weighed. Over the first 24 h there were striking reductions in body weight, core temperature and level of blood glucose. Throughout the succeeding days of fasting, there was a gradual decrease in body weight and core temperature, while the level of the blood glucose was maintained at about 3 mmol X l-1. The decrease in body weight and core temperature was matched by the weight loss of the liver and skeletal muscles. The heart and the kidney and spleen were not affected over the first day, but thereafter their weight declined steadily. The brain, the testes and the lungs retained their mass throughout.