"The employed people just don't feel great about spending," Regan said. "It's tightening the wallet. They're going out, but maybe they're spending less or using a coupon."
(Read more: Restaurants' big bet to get you to spend more)
Christine Caraway, a 27-year-old systems coordinator for a bank, falls into this category. While waiting for her order at a Manhattan McDonald's, Caraway said higher meal costs drove her to cut her restaurant visits in half beginning in 2012.
"I'd rather just cook at home," the Brooklynite said. "They've gotten more expensive and the quality's gotten worse."
Growth spot in dining
Full-service casual dining and midscale or family dining spots have continued to struggle this year. The sectors' names include Cracker Barrel, Denny's, DineEquity's IHOP and Applebee's, Darden Restaurants' Olive Garden and Red Lobster, and Brinker International's Chili's.
Fast-food sales rose 1 percent, with gourmet coffee, doughnuts and bagel companies driving much of the growth.
Still, there is a bright spot in the industry this year. Fast-casual restaurants that serve more premium options relatively quickly, such as Chipotle Mexican Grill and Noodles & Co., had an 8 percent traffic jump in the 12 months through September.
Fast-casual growth has been driven by diners like James Gold, a 28-year-old recent graduate school graduate.
Gold eats out about four to five times per week, frequenting Chipotle along with restaurants that serve pizza and ramen.
"It's convenient— it's not terrible fast food," Gold said about the Mexican chain. "So it's almost my go-to for convenient food."
The millennial diner
Millennials cut back on their spending, even though restaurants continue to test mobile ordering and innovative food items aiming at attracting them.
(Read more: Chick-fil-A joins Starbucks in mobile payments bet)
As that age group struggles with record student loan debt and higher relative unemployment, per-capita restaurant visits by 25- to 34-year-olds dropped to 207 this year from 251 in 2008.
In the total population, by comparison, per-capita visits fell to 193 from 208 in that time frame.