Sarah is terribly overweight, so her doctor puts her on a diet. "I
want you to eat regularly for two days, then skip a day, and
repeat this procedure for two weeks. The next time I see you, you'll
have lost at least five pounds."

When Sarah returns, she's lost nearly 20 pounds.

"Why, that's amazing!" the doctor says. "Did you follow my instructions?"

Sarah nods. "I'll tell you, though, I thought I was going to
drop dead that third day."

"From hunger, you mean?"

"No, from skipping."