Liquid courage? 40 days with beer but no food.

Patrick Berger sounds like he’s promoting the latest diet fad.

“I feel better than I have in a long time. I’m at a weight that I haven’t been at in 15 years right now — and I feel young,” said Berger, who has recently shed 22 pounds from his 291-pound, 6-foot-4 frame.

Except that Berger, who owns Chicago bars Kaiser Tiger and Paddy Long’s, doesn’t recommend the particular diet he began about three weeks ago. To be sure, it takes a certain liquid courage.

“There are much more intelligent ways to lose weight,” he said.

That’s because Berger, 46, has consumed only beer — and some coffee and vitamins. It’s a Lenten quest with roots in 17^th century Bavarian monk culture. And it’s been brewing in Berger’s brain for the last 20 years, he said this week — with the finish line still some 20 days away.

“When I found someone actually did it without dying last year, I was, like, ‘I’ve got to do it,’” said Berger, who sounded far too energetic for a guy who hasn’t nibbled so much as a cookie in three weeks.

Tyler LaRiviere/Sun-Times file

Oddly, perhaps, Berger says it isn’t religious belief motivating him — even though he grew up Catholic.

“This is more of a historical recreation,” he said. “Some people are Civil War re-enactors. I’m re-enacting this famous monk Lenten beer diet.”

Like the Paulaner monks, Berger favors the meatier beers — in particular, the doppelbock variety.

“It’s got a little more oomph, extra carbs, extra alcohol as well and extra calories,” he explained.

Drinking three to four pints a day isn’t much of a departure for Berger, except that, for now, he has nothing to soak up the alcohol. He said he’s had to make sure he drinks lots of water.

“I can’t really get drunk on this diet,” he said. “I did the first week kind of on accident, and the next day, the hangover sucked.”

Berger said he’s health doesn’t appear to have suffered — his doctor checked him out last week — and though it might sound counterintuitive, he says he still really enjoys picking up a glass of the foamy stuff.

“Strangely, yes,” he said. “I’m a sick man.”

Not that he doesn’t miss food.

“I’m dying to get back to eating again,” Berger said. “I’m still trying to wrap my head around the fact I have another 20 days of this.”

And what will he do when it’s all over?

Berger says he’ll slowly ease back into solid food, starting with soup and broth.

“My stomach is basically a deflated balloon,” he said. “If I start shoving things into it, I’m going to get massive stomach cramps.”

And then after about a week, he, his wife and three kids are heading to Belgium, one of Europe’s great beer capitals.

“We’re going to see things besides breweries,” Berger insisted.