I've reduced my diet to the following: apples, canned pineapple, pork steaks, canned corn, and tap water.
The advantage is that none of those contain anything artificial (except the tap water). The disadvantage is that probably no one else would be content eating only those things. But I've been forcing myself, because the alternative is empirically worse.
It's likely I'm just fooling myself. But even still, it's a huge stress relief to not feel bad about we eat.