Illusionist David Blaine has postponed his bid to stay awake for 13 days, because it's his most physically demanding stunt yet.

The 34-year-old is training and dieting obsessively to prepare his body for the world record attempt - which he has already confessed he fears will leave him brain damaged.

The feat was planned for New York City in May - but will now take place in July or August. Blaine tells the New York Post, "This one demands a lot out of me. I run 13 miles a week around Central Park's reservoir. I'm down from 230 to 195 pounds in seven weeks. And of course I'm dieting. My raw diet has brown rice, no red meat or animal products besides fish."

"Nothing fits anymore. My wardrobe's a disaster. I'm using belts. I need to drop another eight pounds and then stay this way. It's not healthy to go up and down."

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(This news article provided by World Entertainment News Network)