It’s a well defined term:
https://en.m.wikipedia.org/wiki/Ultra-processed_food
which the also take some time discussing in the beginning of the article.
Hence, they use the term ultra processed.
On a longer 80-100 year horizon it would fix most of our other problems too!
A swedish submarine officer put it bluntly in an interview today, and i paraphrase: “most likely it developed a crack and instantly decompressed like a crushed soda can”
Your premise is wrong, our diet has never consisted pretty much only of meat. We were hunter-gatherers, gatherer being a very important part of that phrase.
The diet of the earliest hominins was probably somewhat similar to the diet of modern chimpanzees: omnivorous, including large quantities of fruit, leaves, flowers, bark, insects and meat.
It’s a well defined term:
https://en.m.wikipedia.org/wiki/Ultra-processed_food
which they also take some time discussing in the beginning of the article.