Flash doesn't have to eat. He gets energy from the Speed Force.
Once he taps into it, he's all powerful, and would fukk Thor up. He can steal kinetic motion nikka, the shyt that every person uses to move. You can't lift a finger without kinetic energy.
Only people who could beat Flash have to have similar molecular manipulation type powers. Or people who could alter reality. Just say, "The Speed Force no longer exists."
Flash is really unfukwitable...they need to nerf him or something because logically he shouldn't be beat, especially after the shyt he pulled in final crisis