One of the bad parts of processed (and by extension, ultraprocessed) foods is that (depending on the food, of course) a lot of the nutritional value is stripped out during the industrial preparation processes. This leads to the body feeling less satiated by the same amount of unprocessed food, and leads to overeating. For instance, boiling veggies instead of steaming them, because it's more efficient, and then discarding the water that the nutrients leached into.