For lack of food:
* Hungry
* Famished
* Deprived
* Malnourished
* Underfed
* Destitute
For lack of something other than food:
* Deprived
* Neglected
* Yearning
* Craving
* Thirsty (for knowledge, love, etc.)
Figurative:
* Desperate
* Parched (for something metaphorical)
* Longing
* Aching (for something metaphorical)
The best synonym will depend on the specific context in which you are using the word.