To give some insight, when I first started working out, I ate nothing but meat regardless of what kind or how much fat was in it. I never got fat and I know I made muscular gains. But its ME. My metabolism and caloric intake was crazy. I couldnt eat protein shakes without a half cup of hersheys chocolate syrup, for christ's sake.
That was years ago. Since then, Ive incorporated foods into my diet Ive never though of eating...whole grain breads, ONLY egg whites, sweet potatoes (still trying), cottage cheese, grilled chicken not fried, BROCCOLI, ASPARAGUS, etc. Thats right, NONE of this went into my body until now.
My diet isnt perfect, but its much better.
That adage you typed is almost insulting.