NEW YORK – Following the success of fast-casual chains Chipotle and Panera Bread, QSRs are beginning a slow shift to upscale menu items, CNBC reports.

Impressed by the fast-cast segment’s 13% sales lift last year compared to its own 4.7% increase (data from Technomic), QSRs believe fresh ideas can help foster stronger sales growth.

"Right now, our country is pretty saturated with fast food—you could evolve that entire segment into fast-casual," said Sam Oches, editor at QSR magazine. "There's no ceiling on this," he added. "This is just going to be explosive growth for possibly decades."

Accordingly, QSRs are forging into new territory, either by rolling out new concepts or just new menu items.

Yum Brand’s KFC launched KFC Eleven, which does away with the company’s iconic Colonel Sanders and its red and white scheme. KFC spokesperson Rick Maynard described it as an "innovation" restaurant that was "developed with a focus on relevance for today's consumers."

"This innovation lab offers a great way to test new elements—products, services and design—that may end up in other KFC restaurants across the country," he added.

Meanwhile, Wendy’s tweaked its existing lineup, launching flatbread items, and McDonald’s served up Angus beef burgers (the latter experiment has been cancelled). Despite the hit-or-miss of these new items, they’re a safer route than developing an entirely new restaurant concept.

"I think the ones that are choosing to adapt some of these fast-casual [ideas] instead of launching a whole new concept, they still want to maintain their image and still want people to see them as what they set out to be," said Lauren Hallow, an assistant editor at Technomic.