Reviewed - Super Size Me: Director Morgan Spurlock lives exclusively on McDonald's fare for a month in Super Size Me, his satirical documentary that charts the consequences of this diet.

As he piles on the pounds, his sexual prowess declines in inverse proportion, and he encounters health hazards unanticipated even by the many medical specialists he consulted before and during this month spent subsisting on quarter-pounders, large portions of fries and huge containers of "soft drinks".

Spurlock adheres closely to Michael Moore's recipe book for documentary film-making. As the film's narrator and on-screen principal character, he is as cheery, cheeky and chatty an extrovert as Moore, although a lot slimmer to begin with, as he reels off a succession of statistics related to obesity and fast food consumption in the US.

With an air of self-righteous indignation, he addresses the McDonald's tactics employed to lure customers when they are young and impressionable - party areas, the creation of the Ronald McDonald character, the marketing concept that is the "happy meal". (Did you know that there's a hospital in Harlem with a McDonald's on the premises?) Into this mix Spurlock stirs dollops of animation, apt songs such as Queen's Fat-Bottomed Girls, and pointedly quirky instances of "only in America" extreme behaviour.

Spurlock proves to be as full of himself as he is of carbohydrates, and some of the scenes of food consumption (and vomiting) are more gross than many of the excesses of narrative cinema. However, this is a witty, worthwhile and thought-provoking picture - even though, I have no doubt, some viewers will be guzzling and gorging themselves on the junk food sold by cinemas while they sit there laughing at the movie.