Hi, My son is 12 yrs old, and underweight (about 73 lbs, 4'11") .. He does not eat much at all. He says it's like his throat has decided he is full before his stomach does. Feels like it's closing up. I don't know if this is a physical thing, or psychological. He did have 2 occurrances of what may have been Hyperventilation Syndrome last year, but I am not sure whether it's related, or if this is a physical problem. Your advice? Thanks in advance, Tracy.