I’m not making a case for non-vegetarianism here. I am making a case for cooked food.
Humans are evolved to be omnivores, as evidenced by their digestive tracts. We do not have multichambered stomachs or long and large colons that herbivores have.
We are simply not evolved to eat plants, unless made more digestible by cooking.
A predominantly raw food diet will cause malnutrition and unhealthy weight loss. It could also cause irreversible conditions like osteoporosis.
Here is a good article on the issues with raw food diets by Maria Cross on Medium – https://medium.com/@mariacross/raw-versus-cooked-which-diet-is-the-most-nutritious-5e7da97b78f4