Thanks Sage & our thoughtful posters.
I think many diets can work. As many plants as possible, generally.
In Trans Am ‘92, blood tests were done, with extraordinary results. Extreme good health & even low cholesterol after 6 weeks (despite plenty of grease & sugar).
As we evolved, it may have been useful to eat meat in quantity sometimes. It is the only large source of calories in nature, especially during cold weather. Our brains may have become (too?!) large with the availability of more calories. We are pulled in more than one direction here, I think.
As stewards of the Earth, plants use less resources.