Thank you for these links. If nothing else, the UN document at least defines what it's talking about. It's 3rd tier, "processed food", is basically: watch out, they added oil, salt, or other preservatives. The same people worried about "processed foods" are adding their own oil to foods (rightly so, usually!). But when a factory does it,
LOOK OUT!. I mean, yes: watch your salt intake if you eat a lot of canned foods. That's real advice.
It's not until you get to Tier 4 (ultra-processed foods) that you start to see anything legitimately concerning. And indeed if the advice everyone was parroting was "avoid ultra-processed foods as defined by the FAO", then I'd care a lot less about it. Even still, the FAO says that ingredients added to ultra-processed foods include:
> varieties of sugars (fructose, high-fructose corn syrup, ‘fruit juice concentrates’, invert sugar, maltodextrin, dextrose, lactose), modified oils (hydrogenated or interesterified oils) and sources of protein (hydrolysed proteins, soya protein isolate, gluten, casein, whey protein, and ‘mechanically separated meat’).
Avoid sugars and foods with high glycemic indices. Absolutely avoid high-fructose corn syrup. Avoid hydrogenated fats; there is clear evidence they are harmful. Those sources of protein? Health nuts add that stuff to their soy milk all the time! Details matter!
My point is that there are specific processing steps that affect specific foods. Advice on how to identify and avoid those foods is fine. But that's not what anyone is saying: they're saying "avoid processed foods" and "eat whole foods". Those terms are meaningless as they use them. It's non-advice. It's water-muddying bordering on misinformation.