Can three new quarter pounders save McDonald's?

Sarah Coles

Sven Hoppe/DPA/Press Association Images

McDonald's has started testing three new kinds of quarter pounder. It also has a McMuffin made of egg whites up its sleeve. The burgers are hardly world-changing: two of them feature bacon and cheese and the third is a cheeseburger with some extras. However, the fact that is it going for so many menu changes is significant.

It's a sign that the chain is having to work hard to turn its declining fortunes around. So why has it fallen out of favour?