Quite the claim without a source - you're implying that almost the entirety of American healthcare costs are due to people eating vegetables, chicken, pork, fish?
No, I'm okay with people eating eggs, chicken, fish, and any other animal-based food.
Almost the entirety of the American healthcare costs are due to people eating ultra-processed food, which are rooted in grains and seed oils and sugar.
Just cut out every plant-based calorie from your diet and THRIVE.
Vegetables are not as bad as sugar, grain, and seed oils, but they're just full of fiber and anti-nutrients, so they're not beneficial to human health. Red meat also has more vitamins and micro-nutrients that vegetables, whose vitamins are in any case often not bioavailable.
It is honestly almost impossible to put the beneficial effects of the carnivore diet into words -- it would sound miraculous.
Just try it and see for yourself. (And note that it is the diet we evolved on).
