You use את when the direct object is definite... this is usually when the noun starts with - ה, but can also be because the direct object of the sentence is a name or has a possessive suffix. For example, if your wife is called שרה, you can say אני אוהב את שרה. Or you can say אני אוהב את אישתי. This is because אישתי, my wife, means the same as האישה שלי.
If I squint hard and tilt my head a little, it can maybe look like "I like their eater", in the singular, so maybe, the person who is eating them or the person who is eating and belongs to them somehow. But seriously, I need to make an effort to get that. אוכל as a noun is immediately interpreted as "food". :-)