> For me, if I stray into a problematic food, I am intensely depressed for at least a day or more, reminding me of what I worked to 'cure'.

Out of curiosity, do you believe there's a possibility of this effect being mostly (or purely) psychological? I understand that there's a robust and growing body of research linking nutrition, inflammation, gut health, and mental health, but they seem to be either over long timeframes or meta-analysis of other studies. When I read people's reviews of how keto/carnivore/low-carb/vegan impacted their mental health, I'm always wary of statements that link a one or two-time ingestion of a certain food type with a complete relapse of symptoms, although maybe I haven't been properly paying attention to my own body.