FGF21 (IMAGE) Pennington Biomedical Research Center Caption Reduced protein intake triggers a series of adaptive responses in mice. They stop growing, become hungrier for protein, burn more calories, and store less fat. These adaptive changes are dependent on FGF21 acting within the brain. Credit Cristal Hill and Christopher Morrison 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.