Burger King, the second largest hamburger chain, has changed its french fry recipe for the first time since 1998 as competition from upstarts and traditional fast-food rivals mounts.
Burger King said it made the new fries thicker, reduced sodium and added a coating that makes them crisper and keeps them hotter longer.
The fries, now a bit wider in diameter than a No. 2 pencil, will be available in its more than 7,000 North American Burger King restaurants by December 5. Prices remain the same.
"We're always trying to have the best menu possible. French fries are a big seller for us and we want to make sure we're always improving," said Leo Leon, vice president of innovation.
Leon said Burger King tested the new fries against other options.
"This, by far, was the winner," he added.
Burger King's move comes a little over a year after rival Wendy's introduced thinner "natural cut" fries that leave some skin and are sprinkled with sea salt.
McDonald's french fries often take the top spot in customer surveys, but independents such as Five Guys Burgers and Fries, Smashburger and In-N-Out Burger have been dialing up the pressure.
"The competition to have good quality french fries is heating up," said Darren Tristano, executive vice president at consulting firm Technomic, who recently tried the new Burger King fries.
"Making them thicker certainly makes them easier to eat, and since many of them are consumed in the car with one hand on the steering wheel, that's probably not a bad idea."
Burger King said the new fries have 20 percent less sodium than their predecessors.
The smallest, $1 portion has 330 mg of sodium and 240 calories. The fries are cooked in trans fat-free vegetable oil and do not contain animal products, Burger King said.
On December 16 Burger King is promoting its new fries by giving away $1 "value" portions for free. The new fries will be available outside the United States in 2012.
The trend in french fries is toward more "natural" offerings. That includes fries that are or appear to be made from fresh-cut potatoes and topped with "artisan" toppings such sea salt.
"The term natural seems to resonate (with diners), even though there isn't a great definition of natural," Tristano said.
In-N-Out cuts its french fries in its restaurants every day and cooks them in cholesterol-free vegetable oil.
Five Guys cooks its fries in peanut oil and gives customers the option of having them "cajun style."
Smashburger seasons its regular fries with sea salt. It also offers fries made from potatoes or sweet potatoes that are "toasted with rosemary, olive oil and garlic."
McDonald's lately has attempted to reinforce its position as the top french fry seller by promoting its fries, Tristano said.
Investment firm 3G Capital bought Burger King last year and took it private in a $3.3 billion deal. Burger King has 12,400 restaurants around the world.
Reuters contributed to this report.