Emaciated (adjective): bony, thin. Someone who is dangerously skinny and skeletal-looking can be described as emaciated. It’s probably how you’d start to look after a few weeks in the wilderness with only berries and bugs for dinner.
From: A Hunger Artist by Franz Kafka
” While for grown-ups the hunger artist was often merely a joke, something they participated in because it was fashionable, the children looked on amazed, their mouths open, holding each other’s hands for safety, as he sat there on scattered straw—spurning a chair—in black tights, looking pale, with his ribs sticking out prominently, sometimes nodding politely, answering questions with a forced smile, even sticking his arm out through the bars to let people feel how emaciated he was…” Ths statement means that everyone was so amazed by seeing him how skinny he was because he did not eat any bite food or sip of drink for a long time period. And for children, he was a monster looking person in the cage.