IN THE COMMENTS: Pogo tells a vivid story:
I have taken care of a few men like this. One weighed in at over 700 pounds. He was also immobile, and admitted to hospital for a number of related concerns, but they had to cut out the side of his house to get him out (no longer fitting through the door) and transported in a delivery truck (he needed a hoist and didn't fit in an ambulance).
His wife and mother brought him food at home and, despite orders to the contrary, as an inpatient. He would whine and plead like a three year old for food; all guilt and manipulation.
New Year's Eve, 3 months into the stay, he begged to have "just a few pieces of shrimp" to celebrate (exceeding his then 5-to-600 cal diet). I came in the room at midnight to see him holding a huge tray from Red Lobster up to his face, using his arm to shovel the food as fast as possible into his mouth, not even chewing, like in a pie-eating contest.
After we took it away from him, he threatened to kill himself (his frequent ploy to gain sympathy, one that worked on many many caregivers). I was so angry I yelled, "Go ahead. But tell me, how are you going to do it?" I opened up the window. "You can't move, except your arms. You can't walk to this window and jump. You can't even fit through the opening. Frankly, aside from choking on food, I can't even imagine how you'd commit suicide. So be my guest; let us know what you figure out."
His mom started it, it seems. His wife learned to continue the family ritual of feeding him, even long after he quit moving from his bed. I can't explain it, I'm afraid. Some people just can't behave as mature adults, but remain children forever, with appetities insatiable, like Prader Willi syndrome without retardation. C.S. Lewis explains it better than Freud, I think.