They pointed out also artificial sweeteners causing confusion in the response. It's not one smoking gun, it's a ton that end up all counting as "ultraprocessed food". I'm sure if we dumped out HFCS something else in there would end up performing the same function.
I wouldn't be surprised if lots of sweeteners/sugars suppressed the satiation response to some degree. I guess it is beneficial to fruit bearing plants to get us to spread lots of seeds..
