BurnTheShips:
If we hadn't eaten meat, we would never have evolved past the monkey stage. We needed meat to provide the energy for our large brains and it is not unhealthy.
Certainly meat is high in calories but it's possible to get enough energy to survive and thrive from purely vegetable sources. It seems unlikely that the small amount of extra energy intake from meat contributed to the increae in human brain size but the skills needed for animals as physically deficient as the naked ape to successfully hunt almost certainly did.
For example, obesity and diabetes is nearly unknown among the Eskimo peoples who live on a traditional diet.
They're unknown among almost anybody who lives on a traditional diet, including completely vegetarian diets. Obesity and diabetes have reached epidemic proportions only since the introduction of the modern "Western" - read, American - diet.