How diet plan 5:2 became diet plan 6:1

My stomach was rumbling, and seeking a word of advice from one of my friends seemed like the best move.

"Can I have an apple?" I asked her on the phone.

"No," she said firmly, giving me the only word of advice I had not wanted to hear. "All you can have is vegetables, and no fruit," she said, sounding like a dog owner telling its charge that the only bone it can have is the one with no meat on it.