During much of the recovery from the financial crisis, restaurant spending has been a retail highlight as other areas, like department stores, have struggled. According to Stifel Financial Corp. analyst Paul Westra, however, recent surveys point to the start of a serious decline.

"Today, we adopt a bearish outlook for restaurants as we confidently believe that, at a minimum, the simultaneous -150 basis points to -200bps deceleration of restaurant industry comps across all categories during the second quarter within our most recent Stifel Sales Survey reflects the start of a U.S. Restaurant Recession," Westra and his team said in a note.

This doesn't just bode ill for restaurants, but could point to trouble across the economy as a whole. A downturn in dining could be implying a U.S. recession as soon as early 2017, he said, since "restaurants have historically led the market lower during the three to six-month periods prior to the start of the prior three U.S. recessions," Westra adds.