The compelling and hilarious documentary Super Size Me follows director Morgan Spurlock's stomach-churning investigation into America's eating habits. Taking his art to heart, Spurlock bravely eats nothing but McDonald's throughout filming - three meals a day, for 30 days - monitored by an anxious team of doctors and his ever-present camera crew. As his physical and mental well-being deteriorates, he tours America examining the causes of his nation's ever-expanding gut. The results, of both his experiment and investigation, are astonishing.

Spurlock got the idea for Super Size Me when he heard of two overweight schoolgirls who brought a lawsuit against the burger firm. Their suit failed only when they failed to prove that eating McDonald's was injurious to their health. Spurlock sets out to prove just that. Along the way, he meets a wide range of more or less interesting people: smarmy, uncomfortable food industry lobbyists; blithely unscrupulous lawyers; school dinner ladies who only unwrap, never cook; and a handful of provocative academics. Even his girlfriend chips in on their sex life.

"A SURPRISINGLY INTERESTING VISUAL EXPERIENCE"

But it's during the never-ending trips to McDonald's and doctors' surgeries where the film really hits its stride. Spurlock's incredulous GP pleads with him to stop after a blood test reveals serious liver abnormalities. His nutritionist begs him to eat some vitamins. And every time, we cut back to the increasingly overweight and ill-looking Spurlock facing down yet another Big Mac with undiminished, if steely, enthusiasm.

Spurlock's funny and engaging straight-to-camera work and interviews are shuffled with a colourful blizzard of animation, statistics, stills, and ad footage to create a surprisingly interesting visual experience. The film does sag slightly in the middle, its approach is not entirely scientific, and its somewhat facile summing up seems designed to deflate any audience members preparing to applaud. Nonetheless, Super Size Me is a wonderful achievement - entertaining, engrossing, and never far from grossing out.