Most fast food restaurants fry in some form of vegetable oil, with canola, soybean, and palm oil being the most common across the industry. A smaller but growing number of chains have returned to animal fats like beef tallow. The specific oil varies not just by chain but sometimes by menu item, and the formulations have changed significantly over the past few decades.
What the Major Chains Use
McDonald’s is the most well-known example of the industry’s shift away from animal fat. The chain originally cooked its fries in beef tallow but switched to vegetable oil in the 1990s. Today, McDonald’s uses a canola and soybean oil blend for its fryers, with added beef flavoring to approximate the original taste.
Several chains have moved in the opposite direction. Popeyes fries its products in beef tallow. Steak ‘n Shake switched all of its locations to beef tallow for french fries in early 2025, marketing it as a healthier option. Buffalo Wild Wings fries its chicken wings and cauliflower wings in beef shortening. Outback Steakhouse uses beef fat for fried items like its Bloomin’ Onion.
Chick-fil-A is notable for using refined peanut oil for all its fried chicken. Many other large chains, including Burger King, Wendy’s, and Taco Bell, rely on blends of soybean oil, canola oil, corn oil, or palm oil. The exact blend often depends on supply costs, regional availability, and the cooking characteristics each chain wants for its food.
Why Vegetable Oil Replaced Beef Tallow
The original switch happened in the late 1980s and 1990s when dietary guidelines urged Americans to reduce saturated fat intake. Beef tallow is high in saturated fat, so chains reformulated to vegetable oils, which were cheaper and perceived as heart-healthier. The irony is that many restaurants replaced tallow with partially hydrogenated vegetable oils, which contained artificial trans fats. Trans fats turned out to be far worse for cardiovascular health than saturated fat, raising LDL (“bad”) cholesterol while lowering HDL (“good”) cholesterol.
The FDA determined in 2015 that partially hydrogenated oils were no longer “Generally Recognized as Safe.” Manufacturers had until January 1, 2021, to fully remove them from the food supply. In 2023, the FDA issued a final rule cleaning up outdated regulatory references to these oils. The ban effectively eliminated artificial trans fats from fast food fryers, pushing the industry toward newer oil formulations.
High-Oleic Oils: The Newer Standard
With partially hydrogenated oils off the table, many chains turned to high-oleic versions of soybean and canola oil. These come from specially bred plant varieties that produce oil with more oleic acid, a monounsaturated fat. The practical benefits are significant: high-oleic soybean oil lasts two to three times longer than conventional soybean oil before breaking down, which means fewer oil changes and more consistent flavor across a busy shift.
High-oleic oils also don’t need hydrogenation to stay stable at frying temperatures, which is why they became the go-to replacement after the trans fat ban. U.S. farmers planted an estimated 1.4 million acres of high-oleic soybeans in 2025, with projections reaching 2.9 million acres by 2030, driven largely by foodservice demand.
Additives in Frying Oil
Fast food frying oil isn’t just oil. Chains add preservatives and processing aids to extend its usable life and improve performance. One of the most common is TBHQ, a synthetic antioxidant added to vegetable oils to prevent them from going rancid. It works at room temperature and during frying without changing the flavor, odor, or color of the food. Another common additive is dimethylpolysiloxane, an anti-foaming agent that prevents oil from bubbling over during high-volume frying. Both are FDA-approved and used in small quantities.
Peanut Oil and Allergy Concerns
If you have a peanut allergy, Chick-fil-A’s use of peanut oil is worth understanding. The chain uses highly refined peanut oil, which has had its proteins removed during processing. Under federal food allergen labeling law (FALCPA), highly refined oils derived from major allergens like peanuts are not classified as allergens because they don’t contain the allergenic proteins that trigger reactions. Most people with peanut allergies can safely consume highly refined peanut oil, though cold-pressed or expeller-pressed peanut oil does retain proteins and poses a real risk. If your allergy is severe, it’s worth confirming the refinement level directly with the restaurant.
How Often the Oil Gets Changed
Oil quality degrades with use. Each batch of food releases moisture, crumbs, and particles into the fryer, which accelerate breakdown. Fast food restaurants typically filter their oil at least twice a day and fully replace it every three to five days. High-volume locations on the shorter end of that range. Degraded oil produces darker, greasier food with off flavors, so chains have strong financial incentive to maintain their oil even beyond food safety requirements.
Palm Oil and Environmental Impact
Palm oil shows up in many fast food products, both in fryers and in processed ingredients like buns, sauces, and desserts. It’s cheap, shelf-stable, and has a neutral flavor. It’s also one of the most environmentally contentious cooking oils due to deforestation in Southeast Asia.
The WWF tracks palm oil purchasing practices across 285 major buyers globally. Of the roughly 10.1 million metric tons of palm oil those companies purchased, only about 17% was certified to the highest sustainability standards (segregated or identity preserved, meaning it can be traced back to a certified source). Another 32% met a mid-tier standard called mass balance. Nearly 40% was not certified at all. So while many fast food companies have sustainability pledges around palm oil, the supply chain still has a long way to go.
The Beef Tallow Comeback
The recent return to beef tallow at chains like Steak ‘n Shake, Popeyes, and Buffalo Wild Wings reflects a broader cultural shift in how people think about dietary fat. Saturated fat from animal sources is no longer viewed as universally harmful by many nutrition researchers, and tallow has some practical advantages in the kitchen: it’s stable at high heat, produces a crispier texture, and doesn’t require the same additives that vegetable oils need to perform well in a commercial fryer. Whether this trend expands to larger chains like McDonald’s remains to be seen, but consumer demand for what’s perceived as more “natural” cooking fat is clearly influencing the industry.