> Societies that are more resource constrained eat a lot less meat.
They also lag the life expectancy curve by about 10 years. There are a lot of factors at play obviously, but the universal trend is richer countries have better medical care, education, and more complete diets.
Just going to go out on a limb and say the optimal level is probably less than the typical North American or European diet... Societies that are more resource constrained eat a lot less meat.