[dannywoodz]

To a certain extent, he did. From the article:

"Two-thirds of his total intake came from junk food. He also took a multivitamin pill and drank a protein shake daily. And he ate vegetables, typically a can of green beans or three to four celery stalks."

So he provided the calories that he needed with the junk, but kept the processing machinery of his body running with supplements and real food.

I wonder how he'd feel at the end of the experiment if he lost all that weight eating nothing but twinkies.