For years, McDonald's customers had gotten angry at the Golden Arches, mistakenly believing they'd been shorted a whole cheese slice on their Filet-O-Fish sandwiches. But McDonald's has always provided only half a slice for valid reasons.

The fast food giant claims that a full slice of American cheese would overpower the mild, delicate flavor of the lightly breaded fish patties. Besides, a full cheese slice only adds more calories and fat to the fish sandwich that’s already packed with 380 calories and 18 grams of fat.
However, as the appeal of Filet-O-Fish is mainly the fried, breaded fish, McDonald's regulars say asking for a cheese-free sandwich will force the joint to make you a fresh one. If you’re a cheese lover, though, ask for a “cooked-to-order Filet-O-Fish” to get a freshly-made sandwich.