The biggest restaurant brands are investing billions on something that isn't food

If you've been to a fast-food chain recently, you may have noticed things are looking very different than they once did.

Chains including KFC, Arby's, and Panera are in the midst of major redesigns, with Subway reportedly planning a similar makeover this summer.

As brands try to shift customers' perceptions to see the companies as fresher, cleaner, and more modern, the chains are eager to demonstrate these attributes in their design.

KFC is rolling out a new, bold Colonel Sanders-centric design, with plans for 70% of the brand's 4,500 US restaurants to be updated by the end of 2017.

In 2015, Arby's completed remodeling 179 Arby's locations, with the company saying that the redesign correlated with major sales increases. Arby's new design is part of the company's "taste-crafted" image, with a deli-inspired set up that locations across the US can mix-and-match different elements from to fit their needs.

Panera's redesign has been more tech-centric, rolling out a new design that incorporates digital ordering kiosks. The company says that the new tech is cutting lines and wait times, as well as decreasing order errors.

From a purely aesthetic standpoint, these redesigns have a few things in common. Especially at KFC and Arby's, the emphasis is on "bold" and "bright," in contrast with negative fast-food stereotypes of drab and dirty.

While the redesigns are aggressively modern, they also attempt to tap into customers' senses of authenticity and nostalgia. KFC, for example, features a semi-shrine to Colonel Sanders, while Arby's is covered in old-school natural wood.

Highlighting food preparation is also a major trend, in the US and internationally. In Japan, McDonald's remodeled stores to include an open kitchen design to increase customer trust after a human tooth and pieces of plastic were allegedly found in the food. The fast-food giant has also debuted open kitchen locations in Hong Kong.

With Arby's also adding an open kitchen in new stores, the practice may be the new normal as fast-food tries to defeat its negative reputation for serving suspicious food.

In most cases, new technology is less about design and more about functionality, as chains such as McDonald's, Panera, and Chili's incorporate tablets in a variety of ways. However, as demonstrated by Panera 2.0, introducing new tech can go beyond adding a few touchscreen devices - it can change the entire set up of a restaurant.

"Fast food" is out, as more and more restaurant chains try elevate themselves as "fast casual" or, in Arby's case, "fast crafted." A big part of that is design - so look out for more natural wood, tablets, and open kitchens at fast-food giants in the coming years.