During the month of the Impossible Whopper's release, it was reported St. Louis Burger King locations attracted 16.75 percent higher foot traffic than the previous month's average. While states outside of St. Louis, who do not currently offer the plant-based patty, saw foot traffic was 1.75 percent lower than the previous month's average.
"We aren't seeing guests swap the original Whopper for the Impossible Whopper - it's attracting new guests," said José Cil, CEO of Burger King's parent company, Restaurant Brands International, who added that even staff struggle to tell the difference between the two burgers.
Burger King spokeswoman Dori Robau Alvarez said in a statement: "The Impossible Whopper is performing very well in our test markets, and it continues to drive new traffic to our restaurants."
Burger King is now set to launch its plant-based Impossible Whopper throughout the United States, following the success of its trial in 59 St. Louis stores.
"The Impossible Whopper test in St Louis went exceedingly well and as a result, there are plans to extend testing into additional markets in the very near future," a Burger King representative said in a statement.
Impossible Foods itself considers its patty to be plant-based rather than vegan - as a key ingredient - soy leghemoglobin (heme) - was fed to rats in order to test its safety. Around 180 rats were killed as a result of the testing.
The company's CEO, Pat Brown, a vegan of more than 15 years, has reacted to the controversy, publishing a statement titled The Agonizing Dilemma of Animal Testing.