Theres no kaikki (all) in this sentence so I dont think the "maybe the food is all gone" translation is correct.In any case you guys are still fussing over articles, "the" doesnt exist in finnish so stop expecting it.Ehkä ruoka on kaikki loppu might be what you meant to write here.
Check the tips, which have just been updated. Loppu is translated as 'all gone', as in 'finished'. That's a fairly standard way of saying that something is finished. Putting 'kaikki' in front of loppu in that case doesn't make sense.