"I would give him food, but he already has too much."
Translation:Dałabym mu jedzenie, ale ma już za dużo.
Doesn't work or more precisely it works only in negation when accusative changes to genitive.
Its: dawać + Accusative (what) + Dative (to whom), as you learned German you probably know by now that in this language this example works the same: geben + Dativ (wem? was?) + Akkusativ (wen? was?)