Be off his food - Idioms by The Free Dictionary
be off (one's) food (redirected from be off his food)
be off (one's) food
To not be hungry or willing to eat, as due to illness. When I was sick, I was off my food for a week and lost a few pounds.
be off your ˈfood have no appetite, probably because you are ill or depressed: She’s off her food, she’s sleeping very badly and she can’t concentrate.