Please imagine your mother insists that you must eat something and you just don't want to eat because of lacking appetite, what would you normally say?
- I don't have appetite.
- I'm off my food.
For me, both of the sentences above mean exactly the same, but apparently, based on most dictionary definitions, "to be off one's food" implies the message that you're ill, but rarely it can indicate unhappiness too; in the manner that you don't want eat because you don't feel good.
Please let me know if these sentences are interchangeable or not? If not, why?