It is best known for its meal deals, calorie-laden fast foods and for being a guilty pleasure.

Yet McDonald's - home of the Big Mac, Happy Meal, and McNuggets - has discovered how to “trick” customers into choosing healthier meal options.

The revelation came about when the fast-food chain changed the position of items on the menu. It found that customers using touch-screen order kiosks were persuaded to choose less sugary options when researchers changed the order of the list of soft drinks.

The icon for Coke Zero, which contains no sugar, was moved to the first spot on the top left of the touch screens in 622 stores for 12 weeks in 2016.

Meanwhile, Coca-Cola - which contains 140 calories per can - was relocated down the list to the lowest location on the screens.