Graydon Carter is wrapping up a five-week European tour that includes a stay at a chic Austrian spa to drop extra pounds, sources said. The Vanity Fair editor and Waverly Inn/Monkey Bar restaurateur checked into the Viva Centre for Modern Mayr Medicine for at least five days last week.

Situated along scenic Lake Worth in Carinthia, the Centre offers a “symbiosis” of healing therapies and is used by some clients as a fat farm. Patients have reported being put on a diet of chewy stale spelt bread and water with Epsom salts.

It’s run by Dr. Harald Stossier, who teaches a “chewing technique” that gets portly patients to chomp 30 to 40 times before swallowing every mouthful of food. The diet also prohibits caffeine and sugar.

Sources said Carter, 61, was joined at the Viva Centre, which has hosted movie stars, aristocrats and oligarchs, by Vanity Fair special projects editor Reinaldo Herrera Guevara, husband of Carolina Herrera.

The clinic’s top room, the Viva Suite Sea View, goes for 650 euros ($944) per night, according to the clinic’s Web site, while a standard room can be booked for 165 euros ($240) a night.

When Page Six tried to reach Carter by phone at the clinic, a staffer told us he’d checked out last Thursday.

The superstar Conde Nast editor has been on business in London and Europe for a month. A source close to Vanity Fair said that he’d been in regular contact during his trip. After checking out of the Viva Centre, Carter headed off for a vacation with his family, the source added.

We’ll be looking for a stale spelt dish on the Waverly Inn menu when he gets back to New York. A Vanity Fair rep declined to comment.