a book seller named Gary Taubes has taken up the "eat all the fat you want to" meme, after atkins has faded, missleading people with nonsense about how saturated fat is good for you and you can eat all you want as often as you want. he was on the dr oz show debating the merits of his ideas when dr oz challenged him with an offer to publicly run tests checking the health of his heart and vessles. he refused any and all tests.
Eskimos and obesity reflect the addition of carbs to their (modern) diet. They ballooned due to a modern/Western diet. Epigenetically they cannot handle carbs.
dont know for sure but it seems that they would be built to hold fat for survival, warmth,like an africans skin pigment to protect against the sun
Ovolacto vegetarians get moderately less heart disease than either full vegans or "occasional" (<=1 serving/mo) meat eaters, with little difference on other outcomes which in turn is a pretty good indication that animal protein per se is not the problem with meat-based diets. Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies. PMID: 10479225
Many studies also show better outcomes for fish vs non-fish eaters. Vegans and vegetarianism is usually based in philosophical/morality issue than in hard cold science.