Fighting Fat with Fat (IMAGE) Sanford Burnham Prebys Caption Loss of orexin impairs brown fat function and promotes obesity in mice. This cartoon contrasts the consequences of possessing normal and dysfunctional brown fat in the face of a fat-rich diet. The leaner mouse with functional brown fat (left) dissipates considerable amount of energy as heat. The orexin-deficient mouse (right) lacks fat fuel and active mitochondria, thus storing energy as fat instead of burning it. Credit Peter Allen Usage Restrictions Free to use in association with this story only, with credit to Peter Allen. 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.