Again, a fallacy. Our bodies did NOT evolve to become carnivore, but herbivore (fruit, veggie, nut and grain eating herbivore). To support my claim, I offer to you to watch these three videos.

About your friend, it's just an anecdote with absolutely no proof. Studies on thousands of people are obviously true, while your friend's story might as well be just a story.

People with absorption problems need to be careful following ANY diet!