Reviewed by PETER CALDER

(Herald rating: * * * *)

Melodramatic, contrived and extraordinarily entertaining, the film that earned its maker the best documentary laurel at Sundance this year isn't really a documentary at all, but a sustained and goofy polemic that hits the world's biggest chain of family restaurants - and by extension the entire fast-food industry - right in its flabby midriff.

Generously larded with sobering and sometimes horrifying statistics about obesity, consumption and fat content, it doesn't pretend to be a balanced view (although we watch Spurlock try repeatedly and in vain to get a comment from the corporation).

And the film is slightly mischievous in claiming to be responsible for persuading McDonald's to drop its "supersizing" policy, since that was the result of long campaigns by a variety of individuals and agencies.

But it undoubtedly lands some pretty heavy body blows against the multinational marketers of fast food and the corrupted (if not completely corrupt) system of regulation that prizes corporate profit above public health.

The approach Spurlock took to his subject has been widely documented. His health closely monitored by three doctors and a nutritionist, he set himself the task of dining exclusively at McDonald's for 30 days (to the horror of his vegan girlfriend).

The rules: he would eat three meals a day, he would try everything on the menu at least once and he would always accept, when offered, a "supersized" version of his meal.

The results were generally predictable and specifically astonishing. His cholesterol level soared, his weight ballooned - though only by 5kg or so - he experienced wild mood swings and depressed libido and his liver function collapsed to the end-stage cirrhosis levels that might have been expected in a lifelong alcoholic.

Fast-food industry lobbyists have predictably reacted with outrage to the stunt that sustains the film's narrative - nobody eats McDonald's thrice daily, they point out, highlighting the fact that Super Size Me is a sustained statement of the obvious.

Spurlock made his name - and the money to make this film - from an MTV show called I Bet You Will in which people ate jumbo jars of mustard or mayonnaise-infused hair balls and his sensationalist approach here is that of a man who understands the power of reality television.

But it nevertheless makes some telling points about the cynical packaging and marketing strategies that target kids, and the comparative cost of providing healthy meals rather than processed convenience foods in school cafeterias.

The film's appeal also resides in its approachable characters: Spurlock himself is a genial and likeable presence and his bemused cardiologist who keeps circling the numbers on blood test results and shaking his head becomes an almost tragicomic figure.

Inevitably perhaps, the film invites sleekly well-fed middle-class moviegoers to chortle at the gullibility of fast food's real victims, most of whom won't see it - but Super Size Me is part of a cheering trend in cinematic documentaries.

All I want to know is whether the staff who failed to invite Spurlock to supersize his meals got to keep their jobs.

DIRECTOR:Morgan Spurlock

RUNNING TIME: 96 minutes

RATING: M, contains adult themes

SCREENING: Village, Rialto, Bridgeway cinemas