Directed and starring Morgan Spurlock.

An award winning playwright, a beach volleyball commentator, a spokesman for Sony and a documentary filmmaker on a burger binge. The paths Morgan Spurlock has travelled in life have been varied but it is the later which has arguably proved the most rewarding and undoubtedly the most gruelling.

After seeing a news item on two teenage girls in the US suing McDonald's for their obesity (they lost), Spurlock decided to take the phrase food for thought to the ultimate extreme. He would eat nothing but McDonald's for a whole month; he would avail of the chain's Super Size options if offered; he would reduce his exercise to that of the average American; and he would film his descent from days one to 30.

As Spurlock begins his 'adventure', 'Super Size Me' plays like a gastronomic version of 'Jackass', with its star a big kid who can order whatever he wants from that illuminated menu. But as one day's stodge turns into another and Spurlock expands the film - in more ways than one - by travelling around the US to discover just how little people care about what they eat and their level of exercise, 'Super Size Me' becomes ever darker.

While you'll marvel at Spurlock's will to see it through to the end, he loses his sparkle in front of camera because he's depressed and worn out (17 pounds up in the first 12 days) and the statistics and effects of America's eating habits work better than most horror movies. McDonalds, as you can imagine, doesn't come out of it well, but not as bad as Spurlock: it took him 14 months to get his health back to where it was before filming.

But this film is about more than just what's on the menu in the Golden Arches: it's about people's lifestyles and the trouble they're storing up for themselves. Every schoolchild should be brought to see it - with no popcorn during or burgers afterwards.

Six weeks after Spurlock's film debuted at Sundance - where he won the best director award - McDonald's announced it was phasing out Super Size meals but that its decision had nothing to do with this documentary and had been on the cards for some time. Some cynics would allege that if you believe that you really would swallow anything.

Harry Guerin