What are the symptoms of starvation and dehydration?

I saw a movie the other day,it was a true story about how a young woman survived a plane crash in the Amazon Basin.(she was the sole survivor)She made her way through the rain forest eating what she saw the birds and monkeys eat.When she finally came to the river there were some fishermen there and they gave her water and food.She accepted the water but refused the food.She said she wasn't hungry.They made her eat anyway and then took her to the hospital.So I was wondering if a person is starving will they no longer feel hunger pains? Like someone freezing to death no longer feels the cold? And will they have hallucinations as well?p.s. She got water by licking the raindrops off the leaves. Thanks.: )