Comment by antonvs

Let me clear that up for you!

First, regarding other languages, English gets this usage from its Germanic roots, and you still see that in languages like German, Dutch, Swedish, Danish, and Norwegian.

E.g. in German, words and phrases like "aufessen", "Iss deinen Teller auf", "austrinken", "Trink dein Glas aus". Dutch has "opeten" (eat up) and "opmaken" (use up). Swedish has "äta upp" (eat up) and "dricka upp" (drink up).

So really, English just inherited this and has had it for as long as English has existed.

In fact, the same seems to be true of Germanic languages - the widespread existence of this pattern suggests that it comes from proto-Germanic, the ancestor of Germanic languages spoken around 2000 years ago, or even from earlier Indo-European roots.

As for meaning, it's essentially a metaphorical use of "up" as meaning increasing, completing (fill up), appearing/emerging (come up), improving (touch up) - basically movement towards some completed or improved state which is metaphorically viewed as "up".

> Similarly with things like "fed up" (as in 'tired of'). Where is the "upness" here?

The upness is in having reached a maximum. An interesting comparison is "I've had it up to here!" which makes the metaphorical usage much more explicit.