[cypherg]

They've still never actually defined what an "ultra-processed food" even is.

Is it ketchup? Is it protein powder? Is it infant formula? Is it plant-based meat? Is it banana bread?

Is it based on the number of ingredients? Is it based on a preparation method?

This is the core problem with just about every article or study on UPFs

[NoPicklez]

It has been defined many times and it's not a core problem.

https://world.openfoodfacts.org/nova https://en.wikipedia.org/wiki/Nova_classification

There doesn't need to be one formal globally recognised definition if you understand the intent of the meaning of the word.

Ketchup, protein powder, infant formula, plant-based meat and banana bread are all considered highly processed. Banana Bread less so if you decided to make it at home using raw ingredients.

[fragmede]

There’s always going to be a grey area in the middle, but actual spam in a can, and totally prepared microwave dinners are clearly in that category.

[Kirby64]

The gray area is the problem. There's tons and tons of food that is likely healthy, but would meet the "ultra-processed" definition due to including certain ingredients. If those get lumped into the pile, then what is the study actually even measuring? Nothing useful in my view. If you want to make a case that a specific ingredient is harmful by itself (e.g., preservative X added to a food, all else equal, is bad) then I think that's a much stronger argument.

Right now all these studies seem to use broad strokes on the definition of ultra processed that make me think that it would be impossible to accurately remove confounding variables from the study.