Hollywood couple Ashton Kutcher and Demi Moore have committed to tackle the tough Master Cleanse diet once a year - to get their bodies prepared for a potential food shortage.
Actor Kutcher fears the end of the world is nigh and he is doing what he can to make sure he and his wife survive on as little as possible.
So the couple has chosen to exist on nothing but water, maple syrup, cayenne pepper and lemon juice for 10 days once a year.
The Killers star tells Men's Fitness magazine, "If the s**t hits the fan, I like knowing I could live off water and syrup for a couple of weeks."
Moore and Kutcher kicked off their first Master Cleanse earlier this year (10) - and tweeted about how tough it was.
The actor wrote, "hrs (hours) into the master cleanse. I want a steak, a beer, and a blow-pop. Hmmm this is gonna be rough."
Moore, who insisted she was on the cleanse for "health reasons", added, "2nd day better than the 1st! (I'll) let you know if I make it to day 4."
The couple completed the Master Cleanse challenge.