If the diet is done properly, it's composed of whole, healthy foods -- a lot of vegetables, leafy greens, some meats, fruit in moderation, some berries and nuts -- and is a very sustainable way to eat indefinitely. Living on bacon, hamburger, pork rinds, and Atkins snack bars isn't 'doing Atkins' properly, and that's a problem for a lot of people. I have yet to be convinced by anyone that there is risk inherent in cutting out flour and most sugar from one's diet.