score:4
Examples of the losing side getting a net gain in land could be hard to find, but some countries got some land despite being in the losing side.
I must admit that those examples are borderline cases for the conditions in the question, but I couldn't find anything better.
Upvote:3
The question is based on wrong premises: Bulgaria entered the war on the Axis side for many reasons, first of which being it gained territory on Romania (which was part of Axis as well).
Many reasons explained why Romania, under German pressure, accepted to lose territory to many countries: USSR, Hungary, Bulgaria. That is outside the scope of the question. But the point is that Bulgaria entered Axis for territory, and basically gained more by entering Greece's territory when the Germans attacked Greece.
But overall, compared to Romania, Bulgaria fought only a little. Romania and Hungary sent troops against USSR, Romanian troops fighting a lot and being aggressive against the population, for example at Odessa. Romania was probably the third participation to Barbarossa (after Germany and Finland). On the other hand, Bulgaria was a minor participation.
So when the USSR invaded Romania, Romania changed side and fought against Germany. But it was already invaded, while Bulgaria followed Romania example when Soviet forces were at its gates but not on its territory: thus Bulgaria was in better position to ask rewards for changing side than Romania, and that is why Bulgaria obtained the South Dobroudja.
So the premises of the question are wrong: Bulgaria was not a losing country that gained territory. It was a country changing side at the good moment to be on the winning side, so that it gained territory.
Now, do other examples exist? The answer is yes, but in particular circumstances: after the Yom Kippur war, Egypt regained Sinai while it has been beaten.