I was reading THERAPEUTIC FASTING by Arnold Paul DeVries last night. Feeling chilly he says is common, and the remedy is more clothes in daytime, more covers at night.
He also says that most people feel hungry on days 1 and 2, with hunger diminishing on day 3, and gone by day 4 or 5. At this stage, some people actually find food nauseating. But there are a few people, roughly one in forty, who stay hungry all fast. The reason for this was not known. DeVries says that fasting is still effective for these people, but obviously much less pleasant.