@Dark Dragon: That seems like a pretty reasonable analogy, though I'd add for clarities sake that Naruto does produce his own chakra in addition to the 'melted ice' that he gets from Kyubii on an everyday basis. This would also explain the rapid healing, It's not the pure chakra from Kyuubi that heals him but the fact that he has natural access to so much residual chakra from Kyuubi that his body just taps into that when it needs to heal itself. Thus he can 4th tail up and start burning his own skin off with the pure chakra direct from the ice block and heal himself with the chakra that was melted on top.