A study of 3,385 fast-food fanatics found that most don’t realize just how much they’re getting from that greasy paper bag. Two-thirds underestimated how many calories were in their meals by 175 calories, with a quarter underestimating by 500 calories or more! Subway diners misjudged their meals the most—about 20 percent more than people eating at McDonald’s. You might want to keep an eye on those calorie charts, especially if what you’re ordering seems like a lo-cal choice.

READ MORE: The Dangers of Fast Food