Correlation != causation. Your correlation can identify a hugely important effect without pinpointing its mechanism. In this case: I think it's very likely that ultraprocessing has not-very-much to do with food health, but UPF foods tend to be hyperpalatable and low-satiety, which almost certainly does. The ultraprocessing isn't what's making the foot hyperpalatable or low-satiety (the macronutrient mix and sweetening is).

The previous comment was pointing out that there's an agreed-on definition of what "ultra-processing" means. There is. But there is no such agreement on mechanistic effects of ultra-processing.

Yes, I think much of the research is trying to find out what thr cause is, and I agree itslikely to be that hyperpalatable part.

Which statistically significant casual effects have been found?

It's 2 days later, but the effects found in studies are:

- Increased weight gain contain to the same calories in non-UPF - Consumption of UPF linked with obesity - Consumption of UPF linked with early death

As always, I'm sure you could argue with experimental set up, but.those are the main claims.

Source is ultra-processed people, which I mentioned earlier and someone kindly linked to.

Those are correlations found in junk observational studies, not "effects".