Everyone is different, I like to compare Inuits, Eskimos, who used to eat only fat and meat for thousands of years (no fruits, no agriculture in the arctic), vs Jains in India, a cult who are totally vegan, probably also since thousands of years...


So it's obviously possible to thrive on any of these diets, although some of these people might have issues if they had to suddenly switch to the opposite diet! I guess some of their genes have adapted to their ancient way of life.


Anyway this thread was about proteins, and personally I didn't notice much difference at this level when exercising more, but I'm not into HIIT and big muscles, in fact I lost weight so probably some muscles too, since I was already skinny! Of course I need more calories, so more carbs since I'm mostly vegetarian! Maybe higher needs in iron and calcium... but for those who eat red meat these should not be an issue.