YOU SAID:

I eat until I can't eat anymore

INTO JAPANESE

もう食べなくなるまで食べる

BACK INTO ENGLISH

I'll eat until I don't eat anymore.

INTO JAPANESE

もう食べなくなるまで食べます。

BACK INTO ENGLISH

I eat it until I stop eating.

INTO JAPANESE

私は食べるのをやめるまでそれを食べます。

BACK INTO ENGLISH

I eat it until I stop eating.