I know this wasn't directed at me but I have largely cut out UPF after reading the Van Tulleken book and listening to the podcast he did with his brother. I have also, without trying, lost quite a bit of weight - and I wasn't overweight to start with, just at the upper end of the normal BMI range for my height.
I haven't entirely stopped eating McDonald's or drinking (full sugar) Coke. I haven't entirely stopped eating takeaways and ready meals. And I still eat the odd bag of ready salted crisps.
I have entirely stopped eating UPF chocolate, UPF crisps, UPF biscuits, UPF muffins/cakes. These were the foods that I was honestly addicted to and were the things I would low-level binge on. It didn't matter how much of these foods I ate in one sitting, I was never satisfied and never truly full. Despite massive calorie intake from them. Overfed and undernourished!
This change has also largely resolved what I thought might have been IBS symptoms for me. Mostly diarrhoea fairly shortly after eating, or first thing in the morning after eating UPF at night. It still happens occasionally, and it's always linked to eating the UPF that I do still choose to eat sometimes (the McDonald's, the shop-bought sandwich, the ready meal).
So each to their own but for me it has been quite life-changing.
And it's hard to argue that the whole thing isn't essentially morally corrupt: UPF is often the only option for people on a very low income and people who lack the facilities to store and prepare fresh, real food. A cupboard full of UPF doesn't go off, can be quite inexpensive and doesn't need time and energy to prepare before eating. Making it the obvious choice when you're exhausted from working two jobs, when there's no time or money to shop for fresh quality ingredients, when you can't afford to buy or run a fridge or a freezer. So I do think this is much more than a fad, or bad science that will be overturned before long. It's a political issue, and we should all be up in arms about it.