That’s because lax regulations and legal loopholes make it possible for food manufacturers to add very small amounts of trans fat to tons of products—without having to disclose it on labels. And, of course, these little bits add up fast. Here’s what the EWG found: • Trans fat is still ubiquitous in our food supply. At least 27% of the foods in EWG’s massive Food Scores database contain some amount of trans fat. And even though manufacturers and fast-food chains have scaled back on partially hydrogenated oils (PHOs) in recent years, the industry still produced 2 billion pounds of them in 2012—enough for each American to consume 434 g of the stuff in a year.• Of products that contain PHOs, a whopping 87% do not disclose trans fat content on their labels. How? If a product has 0.5 g trans fat or less, the law allows food manufacturers to round down to 0. That’s a problem, since the WHO says adults should consume no more than 2 g of trans fat a day. It would only take four of those half-gram doses to hit the limit—but if you judge a product by its nutrition facts panel alone, you won’t even know you’ve come close.• That loophole is based on outdated science. “It’s from 1991,” says Dawn Undurraga, RD, the EWG’s consulting nutritionist. “Back then, the limit of detection [for trans fat] in lab tests was 0.5 g. In 2015, we can detect 0.1 g. We don’t need to be using 1991 technology to set limits for an ingredient that has such public health importance.” MORE: The Five Absolute Things You Can Add to Your Coffee • PHOs aren’t the only source of trans fats—but they are the worst. PHOs can contain up to 60% trans fat. But refined oils (like soybean, cottonseed, canola, and corn) also contribute an average of 0.6 g of trans fat to Americans’ diets per day, according to the FDA. Emulsifiers called monoglycerides and diglyerides, fully hydrogenated oils, and some artificial flavors and colors can also contain trace amounts of trans fats.• The worst food categories for trans fat might surprise you. We all know margarine and microwave popcorn can have boatloads of trans fat (according to the EWG, some popcorn bags contain up to 5 g!), but they’re not the only offenders on grocery store shelves. Packaged breakfast sandwiches have an average of 0.94 g trans fat per serving. Frozen pies, frosting and icing, snack cakes, and frozen cakes all average 0.5 g or more per serving.• The FDA is trying to change things—but don’t hold your breath. Back in late 2013, the FDA proposed a plan to strip partially hydrogenated oils from its list of ingredients that have received “generally recognized as safe” status. (A final ruling on that plan is expected any day now.) But even if the FDA comes down hard, the EWG says it’s “unlikely” that we’ll see trans fats fully eliminated from our food supply. Food manufacturers could still submit what’s called a food additive petition and possibly win permission to use PHOs again. The FDA proposal is also unclear about the fate of the half-gram loophole—and the EWG doesn’t think it will be closed (meaning we’ll still be left in the dark). So, how the heck can you keep trans fats out of your diet for real? First, remember that “0 g trans fat” might be an outright lie. Always check the ingredients list. Keep avoiding partially hydrogenated oils—they’re still heart-health enemy No. 1. Also limit products with refined oils (again, those are things like soybean, cottonseed, canola, and corn oil), and keep an eye on ingredients that may contain traces of trans fats: fully hydrogenated oils, emulsifiers like mono- and diglycerides, and artificial colors and flavors. MORE: 12 Big Food Companies That Are Going ‘Clean’ If you’re unsure about a certain product (or if you just don’t feel like breaking out a magnifying glass at the grocery store), the EWG’s Food Scores database provides detailed product-by-product reports and will alert you if there’s suspicion of trans fat. Access it online or download the mobile app on your Apple or Android device.