Cancer cachexia is the syndrome of weight loss, loss of appetite, and wasting of skeletal muscle and adipose tissue experienced by many individuals with cancer. Currently, few effective treatment and prevention strategies are available for these patients, due in part to a poor understanding of the mechanisms contributing to cachexia. Insulin resistance has been associated with cancer cachexia in epidemiological, human, and animal research. The present experiment was designed to examine the ability of Exendin-4, a GLP-1 agonist and insulin sensitizing agent, to prevent the development of cachexia symptoms in male Sprague Dawley rats bearing the Yoshida sarcoma. Following tumor implantation or sham surgery, rats were treated daily with saline or Exendin-4 (3 μg/kg body weight/day) and were monitored for tumor growth and cachexia symptoms for 21-23 days. As a result of large variability in treatment effects, data were analyzed separately for animals with large and small tumors. Exendin-4 treatment reduced tumor growth and prevented the development of cancer cachexia symptoms in animals with small, but not large, tumors. In addition, insulin levels were preserved in Exendin-4-treated tumor-bearing animals. The results of this experiment demonstrate a novel preventative therapy for cancer cachexia and a novel use of Exendin-4. Further research is necessary to determine the mechanisms through which Exendin-4 exerts these potent effects.