Nerd!Kimmiekins said:Zucker rats are a substrain that have a faulty leptin receptor - which is a molecule that binds the receptors in the hypothalamus. The rat never feels full, because the leptin can't bind to faulty receptors. So the rat eats and eats. They often (or always? I'm not sure completely...) have type II non-insulin-dependent diabetes. Also, heart, lung and bone/joint problems. Much the same as extremely obese humans.