Morgan Spurlock put on 25lbs (11kg) while making of the film

Spurlock ate nothing but McDonald's food for a month during the making of the film.

The fast food chain took out adverts in five newspapers saying its food should be eaten as "part of a balanced diet".

Spurlock told ScreenDaily.com that McDonald's actions were "a testament to the power of independent film-making".

We've created a film that makes a gigantic corporation examine its business practices and every function Morgan Spurlock, director

McDonald's took out full page ads in The Guardian, The Times, The Herald, The Independent and The Scotsman.

The adverts read: "The film is slick, well made and yes, somewhat annoyingly, doesn't portray McDonald's in the most favourable light.

"And yet what we do agree with is its core argument - that if you eat too much and do too little, it's bad for you. What we don't agree with is the idea that eating at McDonald's is bad for you."

The ad goes on to give details of healthy options such as salads and fruit bags, which McDonald's says is responsible for a 10% global sales increase.

Sundance award

McDonald's has already announced it will scrap super size meals by the end of the year.

Spurlock added: "It's fantastic - we've created a film that makes a gigantic corporation examine its business practices and every function.

"McDonald's love to act like they care about you - but they only care about you if it is good for business."

The fast food chain also took out adverts in Australia earlier this year when the film was released there.

Super Size Me, which won Spurlock the award for best director at the Sundance Film Festival, is due to be released in the UK on 10 September.