Common shrews have one of the highest metabolic rates among mammals. They must therefore consume a considerable amount of energy for their relatively low body weight. Because their fat reserves are quickly used up, they often starve to death after only a few hours without food. Nevertheless, forest shrews and their close relatives are highly evolutionarily successful and quite widespread, especially in the northern hemisphere.
Click here for original story, Shrinking instead of growing: How shrews survive the winter
Source: Phys.org