And no, we’re not talking about obesity here. The research focuses on fast food’s overuse of antibiotics in the animals that end up on your plate. These animals are routinely fed antibiotics to speed up their growth and prevent diseases in crowded and dirty conditions. And just like in humans, frequent antibiotic use can create bacteria that are resistant to the drugs, meaning antibiotics could become useless and leave both people and animals vulnerable to disease. “A post-antibiotic era—in which common infections and minor injuries can kill—is far from being an apocalyptic fantasy, and is instead a very real possibility for the 21st Century,” the World Health Organization recently stated. MORE: The 10 Dirtiest Foods You’re Eating Kind of terrifying, no? So, which fast-food joints are the biggest offenders? Of the restuarants reviewed—researchers focused on the 25 largest fast-food establishments in the United States—only five had adopted policies that limit antibiotic use in their meats: Chipotle, Panera, Chick-fil-A, Dunkin’ Donuts, and McDonald’s. But adopting a policy doesn’t necessarily mean those restaurants earned top marks (the chains were also graded on transparency). While Dunkin’ Donuts has a policy that limits antibiotic use in all of its meats, the chain is not clear about what meats are currently antibiotic-free or when it plans to enact a no-antibiotics plan. DD’s sketchy timeline dropped the coffee chain down to a C. But Dunkin’ isn’t the dunce in the fast food/coffee shop world. Our beloved Starbucks absolutely tanked this report card with only one measly point (out of a possible 36), given for mentioning plans for an antibiotic policy online. In fact, a not-so-shocking 20 of the 25 restaurants included in this review got an F, bringing the class average down to a dismal 19%. MORE: 8 Reasons Why You’re Still Eating Fast Food In company with Starbucks on the F train are: Subway, Wendy’s, Burger King, Denny’s, Domino’s, Olive Garden, Papa Johns, Taco Bell, Pizza Hut, KFC, Applebee’s, Chili’s, Jack In The Box, Arby’s, Dairy Queen, IHOP, Outback Steakhouse, Little Cesar’s, and Sonic. Only two of the restaurants included have a report card worthy of hanging on the fridge. Chipotle and Panera both earned As for having policies that restrict antibiotic use in nearly all of their meats, and for being upfront about antibiotic use. Both chains have also vowed to remove all artificial ingredients from their menu items in the near future. While the researchers compiled the report in hopes that it will encourage restaurants to change their policies regarding antibiotics, they also remind consumers (that’d be you) that they can help, too. “Your choice and voice matter,” the researchers write in the report. “You can support farmers that raise animals without the routine use of antibiotics and choose restaurants that offer better meat options for you and your family.”