Credit: Michael Bezjian/; Stefanie Keenan/

Spencer Pratt - whose sister Stephanie was arrested for DUI Oct. 18 - admits it's easy to get caught up in the wild Hollywood lifestyle.

"I mean, I've had problems with drinking in Hollywood, but who doesn't?" Pratt, 26, tells MTV News.

He says when you're having fun, it's hard to realize that there's anything wrong. It also doesn't help when club promoters and bar-goers are "giving you unlimited high-end alcohol," he says.

"If you're out at a club every night having drinks, then you're drinking every night of the week," he says. "First, it starts off, 'Oh, I just love this dancing and having fun with friends.' But it's like, even though you're just having a couple of cocktails, [it adds up]."

Ironically, it is sister-in-law Holly Montag whose drinking is scrutinized on the current season of The Hills.

He reveals that on an upcoming episode of The Hills, he and Heidi had to "step in."

Says Spencer, "Tune in — you'll see it when it clicks, when we're like, 'Yo, it's time to help Holly.'"