"They are eating despite not being hungry."

Translation: Jedí, přestože hlad nemají.

[JanisaChatte]

Is ač a synonym for prěstože?

[ortocymen]

Yes, "přestože", "ač", "ačkoli" and "i když" are interchangeable in this type of sentence. One sentence is positive and the second one negates it. "Přestože" and "i když" are more common, "ač" and its' longer form "ačkoli" are rarer and rather used in books.

"Jedí, přestože/i když/ač/ačkoli hlad nemají."

"Šel jsem spát, přestože/i když/ač/ačkoli jsem nebyl unavený."

[IonutDumit561410]

"Jedí, přestože nemají hlad" is not accepted. Could anyone explain why?

[VladaFu]

Your report says "Jedí přesto přestože nemají hlad". It is necessary to double or triple check the answer before reporting and when asking in the discussion you have to copy your answer exactly.

[IonutDumit561410]

Ah, I see, sorry about that.

[Paul378887]

Could “přesto” work in this sentence in place of “přestože” without changing the meaning?

[VladaFu]

no, it would mean "and despite of that they are not hungry".