My focus has been on Viljhalmur Stefansson, the Canadian Arctic explorer who lived on an all meat diet with various indigenous groups and again as part of a year-long experiment.
He noticed that he was more positive, focused, and felt healthier "on meat". The tests done by the research team bore these claims out as well.
Also, contrary to popular opinion, even among Paleo/Primal circles, he did not find that consuming offal or rare meats was required to sustain health.
He was a heavy meat eater all his life and lived to the ripe old age of 83.
My curiosity has obviously been aroused and I am wondering if anyone here has followed a meat-only regiment similar to Stefanssons. (Which, in case you are wondering, was comprised of flesh, fat, some organs, bones, and broths, but no eggs, dairy, or supplementation.)
(This is a picture of Stefansson while on expedition)