By Rebecca Heilweil

Fast food and casual dining joints including Burger King, White Castle, Red Robin, and TGI Fridays have all jumped on the plant-based meat train led by Beyond Meat and Impossible Foods. But with that growing interest, demand has ballooned by so much that some restaurants are facing plant-based meat shortages.

"In some ways, they've been taken by surprise. For a long time, this was a niche product that was served in higher-end restaurants, sit-down meals," says Heather Haddon, a food reporter at the Wall Street Journal. "Beyond Meat, which has traditionally sold more in retail chains, seems to be now expanding into restaurants because Impossible Food really has had a hard time keeping up."

Haddon's [recent article] ( on the subject reports that meat alternatives produced by Impossible Foods and Beyond Meat are now served by just under 20,000 restaurants. The overall number of restaurants that serve plant-based meat alternative burgers has grown by 3 percent since last year, according to a study from Technomic, a consulting firm focused on the food and food services industries.

"In Hong Kong, it's in a dumpling and a bao. It's in meatloaf. In Boston, it's served chain-wide at Clover as a breakfast sausage patty," said Impossible Foods CFO David Lee [told Cheddar] ( in an interview last month. "It can be anything the chef wants it to be."

"Our approach was to be in the hands of great chefs so that meat-eaters would have the best chance of having a great Impossible Burger and to expand our awareness before we go to retail," he added.

Millennials have been leading demand for plant-based food products, and close to 80 percent of the age-group consume meat alternatives, according to Mintel research [previously reported] ( by Cheddar.

But these restaurants haven't managed to keep up with demand, despite both companies seeing new influxes of cash. Beyond Meat experienced the most successful public offerings this year, and Impossible Foods raised $300 million in a recent funding round.

In the meantime, chains like Arby's and McDonald's are remaining more cautious, unsure yet if the flurry of imitation meat has staying power.

Haddon says that the president of Arby's told her, "'Our traditional meat tastes better. We're not playing in this space at all,'" she says, to which she added, "There's still a lot of questions as to how sustainable this is."

And while McDonald's offers some vegetarian options, it has yet to partner with either Impossible Foods or Beyond Burger.

"They recently had a question at their shareholders' meeting about this. Executives really say that they're taking a cautious approach. The chain is really trying to limit adding new things to menus where they really haven't established that there will be demand that is significant and sustainable."

"When you're talking about a company as big as McDonald's, it really changes things for both the company themselves and obviously all their franchisees," Haddon adds. "They've added a lot of elements to their menus so before adding this, they really want to make sure that there's demand, and that customers are interested in this."

For full interview click here.