I thought the most fitting name for an upgraded "Hungry" is "Starving"...
I like "Ravenous" personally.
Starving implies that the onset of physical weakness has begun as a result of malnourishment.
Ravenous, on the other hand, is simply an extreme version of hunger (desire for food).
Ravenous does not necessarily imply that any adverse physical effects have been felt yet whereas starving does.
... Starving would be better in a case where the creature would weaken if left unfed... which could be an interesting twist I suppose.