I don’t know. Something about eating a lot of fiber. I cant do it for example. I eat some veggies, but probably not “enough” fiber compared to modern recommendations and i cant process it. I am doing OK without it from subjective perspective. Also i am interested how much nonsoluble fiber did regular people eat before modern vegetable and fruits. Potatoes and cabbage, wheat and some roots and max some berries max.

Like where would the need for the fiber come from evolutionary.