Today, it is commonly recommended to eat a high protein diet (along with exercise) for strengthening the body and for less uncomfortable time in old age. I was wondering if the amount of protein content of the diet impacts the energy in different ways - specifically, could a low protein diet be helpful in increasing and purifying the energy in the body?

I ask because of the following reasons:
a) On Reddit, on a different sub, a few weeks ago, someone shared a passage from a European book from a 100-200 years ago, translated into English, which said, among other things, that a low protein diet will help increase the energy and the energy be purer. (Everyone on that sub agreed that all the other facts in the passage were all true, insightful, and went against modern conventional wisdom.) The passage did not say anything about vegetarian versus non vegetarian diet, though the uploader mentioned that the author recommends a vegetarian diet at another place in the book, but the author also says that it is not mandatory.

b) When I think of what I know about spiritually evolved people from the Eastern traditions (Zen monks, for example), I believe they eat a low protein diet. (Most even eat a strictly vegetarian diet, which is again likely to be low protein.)

c) At vipassana retreats also, I am told that the diet is relatively low protein (even in percentage terms, accounting for lack of exercise and physical exertion in the retreat), but everyone seems to come out full of energy.

d) All the people I know who eat a high protein diet have an unpleasant energy about them, even if the physical bodies are sculpted closer to perfection due to many hours in the gym. They also seem to have lower energy, unless they are doing a lot of cardio. (So I agree cardio increases energy.)

I am not focusing on vegetarian versus non vegetarian diet here, but specifically on the impact of protein content in diet. Do you have any insights?