McDonald's finally reveals why Filet-O-Fish only has half a cheese slice

The Filet-O-Fish might be one of the last things you think of when you're heading through the McDonald's Drive Thru.

But, while the fast food restaurant undeniably has more popular offerings - take the classic Quarter Pounder with Cheese or a portion of McNuggets for example - the perfect combination of fried fish, tartar sauce and cheese has gained its own mightily loyal following.

There's just one question fans have when it comes to the Filet-O-Fish. Why does it only have half a slice of cheese in it?

The classic dish, which became a permanent item on the McDonald's menu way back in 1965, was first devised by franchisee owner Lou Groen as a way to attract customers to the restaurant during Lent.

But the sandwich, which originally consisted of fried halibut and tartar sauce on a bun - no cheese - wasn't an instant hit, with executives at the fast food chain's headquarters unconvinced by the idea.

However, Groen's invention proved popular with customers and the big guns finally relented, making it a staple of McDonald's menus everywhere.

At the restaurant's request, however, Groen was forced to swap halibut for a cheaper fish. He also made a small but vital addition to the dish.

In an interview with the Cincinnati Enquirer, he said: "I had to fall back on Atlantic cod, a whitefish, and I added a [half] slice of cheese. But my halibut sandwich far outshines that one."

There's a very specific reason why McDonald's only puts half a slice of cheese on its Filet-O-Fish (McDonald's)

There have been a few small changes to the Filet-O-Fish over the past six decades but half a slice of cheese has remained constant. But, while you may accuse McDonald's of being a bit stingy, there's a very good reason why they don't add more.

"We only use half a slice of cheese because that’s exactly the perfect balance for the tangy tartar sauce and crispness of the Filet-o-Fish coating," a representative for McDonald’s Canada told an inquisitive customer on X back in 2012.

They continued: "We use a whole slice on our Double Filet-o-Fish. Anything more than that would throw off the mojo of the sandwich and overshadow the delicate flavour of the pollock."

Other X posts from the fast food giant claim they do it to 'save on the flavour of the sandwich'.

That being said, if a mere half a slice of cheese doesn't feel like enough, McDonald's insist they won't be offended, with a page on the US website reading: "Of course, you can always ask for 'extra' cheese the next time you order a tasty Filet-O-Fish. It’s the 21st Century, after all."