Someone who is “off their food” has gone without the appetite they would normally have, usually because they are unwell, upset or worried about something. It is a mild, everyday way of describing a loss of interest in eating rather than a medical diagnosis, and it is often taken as a sign that something is wrong before any other symptom appears. Cambridge Dictionary records “be off your food” specifically as a British idiom, defining it as meaning to not want to eat, usually because you are ill.
What’s the origin of the phrase ‘off your food’?
The phrase grows out of an older expression, “off one’s feed,” which began life as a literal description of livestock. “Feed” in this sense meant fodder, and an animal described as off its feed was simply one that had stopped eating normally, a plain warning sign to anyone tending horses, cattle or other stock. From there the expression was carried over to people, describing someone who had lost their appetite in the same straightforward, physical sense.
The earliest clearly dated example of the idiom applied to a person, still in its older “feed” form, comes from Charles Dickens’s Master Humphrey’s Clock, published in 1841. A character describing a sick acquaintance says he “wos took wery bad one arternoon, arter having been off his feed, and wery shaky on his legs for some veeks.” The phrasing shows the expression already comfortably established as a way of describing human illness, carrying across directly from its origins in describing animals that had gone off their fodder.
Over time “feed” was gradually replaced by “food” in everyday use, giving the modern wording. The sense has stayed essentially the same throughout this shift: whether said of a horse or a Victorian invalid, being off your food or off your feed means the same loss of appetite, usually read as an outward sign that all is not quite well.