For an individual to cut all grain and carbs out of their diet is relatively easy (whether that's actually a good idea is another matter.) For the whole popul

For an individual to cut all grain and carbs out of their diet is relatively easy (whether that's actually a good idea is another matter.) For the whole population to do it? You'll need something to replace these for billions of people, ideally without causing mass starvation: https://en.wikipedia.org/wiki/Staple_food#Production https://en.wikipedia.org/wiki/Staple_food#Production Good luck.