One study found that eating meat increases the workload on the kidneys within hours of consumption, while processing plant protein did not have the same effect.
https://pubmed.ncbi.nlm.nih.gov/2166857/
The book covers about 500 studies so they can't be all summarized or lumped together.
Some diets that may have short term benefits like weight loss are not good for longevity.
Those who have studied long-lived populations recommend a 95% to 100% diet based on what's worked for our oldest populations.