Mammoth task for Toby

For the past year or so I've been meaning to get in touch with McDonald's to see if they'd be interested in funding a riposte to Super Size Me, Morgan Spurlock's attack on the fast-food corporation.

If you recall, the 34-year-old documentary-maker ate nothing but McDonald's for a month and then recorded the effects on his health. Not surprisingly, he gained 25lbs, his cholesterol level shot up by 60 points and his liver turned to foie gras.

My idea was to make a similar film, only I'd spend 30 days eating the most expensive food in the world rather than the cheapest. I can absolutely guarantee that by the end of this experiment I'd be every bit as unhealthy as Spurlock.

If I ever make this documentary, my first port of call will be the Big Easy Bar BQ & Crabshack. Since opening its doors in 1991, this American surf 'n' turf restaurant on the King's Road has been renowned for its huge portions, but at the beginning of this month they went one better and introduced the Lobster Challenge.

This is a plate of food that includes a 2lb steak, a 1lb portion of chips and a 4lb lobster, making it Britain's most calorific meal. If you can finish it in one sitting, your name goes up on a board in the basement.

Technically speaking, I'm supposed to be on a diet. Working as a restaurant critic for the past three years has taken its toll and I'm now two stone heavier than when I started. But I can't resist a challenge and this seemed a lot less strenuous than running a marathon.

'Are you sure you want to try this?' asked my waitress, a perky Australian called Amy Demblon. 'Only two people have managed it so far and they were both a lot bigger than you.' 'Bring it on baby,' I said.

Big Easy is modelled on the informal seafood restaurants of America's Gulf Coast, with plain, utilitarian furniture, chequered tablecloths and plastic bibs for those who want to avoid getting crabmeat on their Hawaiian shirts.

It's so laidback, it could almost be one of those bars in the French Quarter of New Orleans where the drinkers were undisturbed by Hurricane Katrina. My fellow diners all looked as though they'd consumed several jugs of frozen margaritas before sitting down to tackle one of the restaurant's gigantic meals.

When the Lobster Challenge arrived, my companion and I had to move to a larger table so the waitress could put it down. The plate was - literally - the size of a dustbin lid. It looked less like a large meal for one than a small wedding banquet. How on earth was I going to manage it? As the enormity of the task I'd set myself began to sink in, the head waiter appeared with a stopwatch and told me I had just 45 minutes to polish it off.