And I don't think the diet as described, most calories from meat, cheese and eggs, is the most healthy. Perhaps healthier then any diet high in processed sugar, depending on individual physiology. I certainly agree sugar is bad for you, but I think a "mostly plants" diet, is still better for most people.
Go take a walk in practically any ecosystem and find edible stuff that's not an animal. There's barely anything. Primitive man clearly ate mostly animals and fish.
There are abundant written accounts of native north americans. There were those who grew corn and squash, which means they have little in common with paleolithic humans who had no such crops. And there are those that did not grow crops and ate mostly game and fish.
Anywhere away from the equator there is virtually no gatherable plant food for most of the year. Before domesticated crops, people clearly ate mostly animals, fish, and insects.
- I'm not sure how much it matters what we ate 20,000 years ago. For example, lactose tolerance is assumed to have developed very recently in most places. People are opportunistic omnivores and it would make sense for them to be able to adapt quickly (several generations) to new eating habits.
- Guessing what people ate is tricky. If all we have to go on is modern evidence, we have a huge level of disparity. Also, just because (for example) New Guineans were primarily hunter gatherers in modern times doesn't automatically mean they were similar in every other way to pre historic Europeans.
You respond to this contrary evidence by simply restating your claim. There was "virtually no" plant food, and people "clearly" lived mostly on meat. Do you have any evidence at all?
It bears repeating the simple fact that most places don't have wild plant food for most of the year. Pick up the army survival manual. It's mostly about how to fish and trap in many different ecosystems, because, as it explains, there isn't much wild plant food out there most of the time.