She wanted to eat, to enjoy delicious food, but she had no appetite.
She even just wanted to get a good night's sleep, but damn it, she suffered from severe insomnia. Her body would say, "Sleep my ass, get up and party, you might just drop dead anyway."
...
If you lose your humanity, you lose a lot; if you lose your beastly nature, you lose everything.
The first sign of losing your beastly nature is a lack of will to live. All the self-defense mechanisms evolved for survival just shut down completely.
Although a witch wouldn't die from hunger, thirst, or shivering, the feeling of desire coming but your body being unable to respond was awfully frustrating.
So, to stop her pitiful Dragon Nature from so easily "committing suicide," Dorothy started painstakingly "caging" it.
