Skinny Mouse on High-Fat Diet (IMAGE) Washington University School of Medicine Caption Washington University researchers activated the Hedgehog protein pathway in the fat cells of mice. After eight weeks of eating a high-fat diet, mice that had been engineered with genes to activate the pathway didn't gain weight (left), but control animals whose Hedgehog pathways were not activated became obese (right). Credit Washington University School of Medicine Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.