hunger pang or pain?

[aha]

pang n 1: sudden sharp painful emotion; "pangs of regret" or "twinges of conscience" [syn: twinge] 2: a mental pain or distress; "a pang of conscience" [syn: sting] 3: a sharp spasm of pain.

That is what the dictionary describes as a pang. Notice it says a sharp spasm of pain.

I have never thought of that first feeling of hunger as a feeling of pain. Maybe I haven't been hungry enough but it doesn't seem like the same kind of thing that I think of when I think of pain.

Anyone got a better definition of hunger pang or what goes on in the brain when hunger sets in?