Processed foods are part of the problem (in that they are tastier and easier to consume than "rawer" foods), but increased wealth and ability to consume food is also a part of the problem
Food has literally never been cheaper and tastier
Even quick snacks found at U.S. gas stations (when I'm running late) consist chiefly of mass-produced, sugary, heavily processed desserts like Twinkies and HoHos, whereas options for fresh fruit and locally made goods with natural ingredients are often not to be found. I take a pass and look for an open supermarket instead. I doubt that it is a supply chain issue: in the north of Scandinavia and Canada, the outback of Australia, and especially through Asia it is almost always possible to get somewheat healthy quick snacks of a local variety at roadside petrol stations.
As a large man who exercises a lot I do refuse to patronize restaurants that serve tiny portions (unless I'm specifically intending to order multiple small plates for tapas or sushi or something). And you're exaggerating with the "3k calorie meal" thing. That rarely shows up on real restaurant menus. Most of them top out at around half that much for a regular entree and a customer would have to add beverages, appetizers, and dessert to reach 3k.