Fast food giant Burger King is facing a lawsuit amid claims its Whopper burger is made to appear bigger on menus than it does in reality. The legal case is set to be heard in the US after being ruled on by District Judge Roy Altman, who said it should be left to jurors to "tell us what reasonable people think". Customers are complaining the burger is 35 per cent smaller than advertised. The class action lawsuit is accusing Burger King of false advertising. But it is not the only fast food company to be targeted amid a series of legal cases in the US contesting the gap between advertising and reality in fast food. McDonald’s is defending allegations its burgers shown in marketing are at least 15 per cent larger than they are in real life, with the separate lawsuit being contested in Brooklyn, New York. Burger King is facing allegations that ingredients are shown to "overflow over the bun" in adverts and on menus, while the burger is also illustrated with a meatier patty than experienced in real life. A Burger King spokesperson said in a statement after the ruling: "The flame-grilled beef patties portrayed in our advertising are the same patties used in the millions of Whopper sandwiches we serve to guests nationwide." Burger King was founded in 1953 as Insta-Burger King, as a Jacksonville, Florida–based restaurant chain. It became the world's third biggest fast food chain by the 1970s and is widely known for its advertising, in particular the branding of the Whopper, dubbed the company’s ‘flame-grilled burger’.