Mark himself will often workout fasted and then not eat afterwards for quite some time as well.
His perspective: Post Workout Fasting | Mark's Daily Apple
"The cling and a clang is the metal in my head when I walk. I hear a sort of, this tinging noise - cling clang. The cling clang. So many things happen while walking. The metal in my head clangs and clings as I walk - freaks my balance out. So the natural thought is just clogged up. Totally clogged up. So we need to unplug these dams, and make the the natural flow... It sort of freaks me out. We need to unplug the dams. You cannot stop the natural flow of thought with a cling and a clang..."