A uniform metallic rod rotates about its perpendicular bisector with constant angular speed. If it is heated. If it is heated uniformly to raise its temperature slightly 

$KE=\frac{L^2}{2I}, L=I\omega$

Since there is no external torque, angular momentum remains conserved. Due to heating, rod expands and distances of various mass points from axis of rotation increase. Hence moment of inertia increases. Since, moment of inertia increases, angular velocity and KE both decrease.