Considering their diets, which were very high in carbohydrates (not sugars though) compared to modern diets that seems highly unlikely. Can you actually ever enter "ketosis" if you're mainly eating bread and other grain products?
> i think ancient people needed salt because they would get sick without it. but eveyone says its because they liked the taste
They needed salt because there weren't that many other ways to preserve food. I doubt this has much to do with taste. Also modern people need salt too..
> ancient people didnt eat as much
That's debatable. According to our records medieval people did sometimes eat quite a lot. I guess the problem is that it varied a lot. You either had too much or to little food all of the time.
Why? Of course Northern European had different diets (e.g. lard instead of olive oil etc.) but on the Mediterranean cost diets weren't that similar.
> you can enter ketosis every day on a diet of carbohydrates by eating one or two times a day
So being on the brink of starvation all the time? Does not seem sustainable.
> all of this could have applied to most people until relatively recently
Highly unlikely. What makes you think that was the case?
> had almost none of the diseases we have that are all really metabolic dysfunction/diabetes at their root
True. Unless you were rich. Even heard of gout? But yeah probably somewhat accurate for the whole population. But again, not much to do with ketosis.
I mean is there any evidence even today that someone whose diet is primarily (~80%) grain and other plant products with a lot of carbohydrates can enter ketosis even when practicing "intermittent fasting" while consuming ~2000-3000 calories per day (e.g. the estimate for standard Roman soldier daily rations is 3,000-4,000)? Seems impossible...
> its extremely well established science
You saying this doesn't make it true.
Not sure what you mean by that - at a time when people were largely self-sufficient and working the land, they obviously consumed enough calories for the work they were doing. The food may not have been great (a lot of bread!), but there would generally have been enough of it unless having to tough out the winter after a poor harvest.