My mother, at around age 80, weighed 98 lbs. She had been a healthy eater all her life. She never had a documented stroke but we noticed she would get up from a big meal, would be totally distended and say, "I'm starving." I tell her it was not physiologically possible. Didn't matter. Her weight went up to 128 lbs. in a matter of a couple of years. We would tell her doctor something was very wrong and I assumed it was neurological, but we were ignored. Of course, then she developed heart disease and died during an attempted angioplasty. No help to offer here - just a corroboration that this has happened before. A neurological cause was the most obvious to me.