If we look at the evolution of our gut, and our gut microbiota...we were not meant to eat animal protein heavy diets.
Our closest primate relatives, chimpanzees, orangutans, gorillas and bonobos...are omnivores who eat very little meat. Most of their diet is fruit, vegetables, nuts, leaves, bark...tons of fiber. Tons of plant matter. Tons of sugar..fruit, figs, honey. Tons of carbs. And a small amount of bugs, eggs, and meat. A very small amount. Like 5-8% of their diet.
Interestingly....the people on Earth who have the longest lifespans and least heart disease and cancer....eat a diet very similar to our primate counterparts. Mediterranean Diet includes lots of complex carbs, lots of fruit and vegetables, nuts, olives, plant oils, fiber...and a small amount of meat, eggs, dairy. The bulk of daily calories comes from high fiber carbs.
Thinking about the human digestive system, and the human renal and cardiovasuclar systems....the idea of doing an animal protein heavy diet that limits carbs... for more than a temporary period of time... quite frankly....scares the hell out of me for the future of my heart and kidneys. We just weren't built to eat this way.
Dr. Atkins...of the Atkins high protein low carb diet died at 72. A medical report issued by the New York medical examiner's office a year after his death showed that Atkins had a history of heart attack, congestive heart failure and hypertension. His widow would not allow an autopsy.