possible over reaction to the "hunger" response of the body. as hypos, we focus on every bodily sensation, even the noormal ones, so its very possible that when yu get hungry, your brain gets a little anxious, causing an exaggeration of symptoms. once yu eat, your brain knows that's the "cure" for your problem, thus the anxiety fades.
try eating 5 to 6 small meals throughout the day t keep the hunger at bay. I've had the same and this worked for me.
hope ya feel better! =D