Why does hunger tend to go away when on a starvation diet?

Ketosis. At some point your body will switch to breaking down your energy stores and convert it to ketones which are an alternate fuel for your body. Unfortunately it begins with muscle before fat and that is why individuals on the adkins diet often lose muscle which is not good as that is your fat burning machinery. Please use a good diet such as "paleo" or "the perfect 10" to avoid damage to your health.