The mission: Colds must be fed. Where better to test this out than an `all-you-can-eatery'? Matthew Sweet suffers for science

wo phrases underpin this week's mission: "Feed a cold" and "All you can Eat". And this is the story of their horrible collision. Some people have tested the limits of the human frame by scaling mountains or blasting themselves up into space - either of which I would have been prepared to do to furnish material for this column. Instead, I was forced to take up a less noble challenge - testing how much food one human being could consume in a day. A fairly greedy human being with a stinking cold. Anyone with a weak stomach should probably now flip forward to the Crossword.

Breakfast is three Shredded Wheat, a tough assignment for anyone with a gippy throat, so I take a preparatory Menthol Lemsip to dull the pain. People say that Shredded Wheat has the taste and texture of mattress-filling, but I find it quite agreeable. (Shredded Wheat that is, not mattress-filling.) Eating three, however, is hard work - mainly because of the combination of fatigue and boredom that hits you halfway through your second one.

By 1pm, I'm hungry again, and looking for a challenging lunch. London's Pizzaland on Charing Cross Road currently has an all-you-can-eat offer. Rather tempting, you might think, until you peer through the window and see the sorry mulch of pasta and limp slices of pizza that are busy losing their flavour on the hotplate. I march bravely in, and get a table at the back so that I can't be seen from the street by anyone who knows me. After my first five slices, the novelty of this cornucopian experience is wearing as thin as the topping on a Pizzaland pizza. The burpy drink they throw in is no help to the digestion, either. One slice later, I've surrendered.

At 6pm, I think I could manage a bit of dinner. So it's off on the Heathrow Express to visit my nearest branch of Harry Ramsden's, in order to take up the gauntlet of Harry's Challenge, a full-on ultralard experience that very few have had the stamina to complete. To my surprise, I realise that the man in the seat parallel to mine is Irvine Welsh. I think about asking his advice on excess and indulgence, but I'm still a bit queasy from the pizzas, and don't want to run the risk of puking over a celebrity.

I'm disappointed to find that the waiter at Harry Ramsden's in Terminal One is from France, rather than Yorkshire. He explains the terms of Harry's Challenge: "You merst eat everyzink. Not on ze table, not on ze floor". Moments later, dinner arrives. It is a gigantic deep-fried version of the Krypton Factor assault course. There is a shovelful of chips; two large ramekins of mushy peas; a big pot of tartare sauce. Most frighteningly, there is a monstrous battered halibut that hangs over the edges of the plate.

Feeling a little like Captain Ahab going for the kill, I tuck in. And it's good. Very good, in fact. The mushy peas are nice and vinegary; the batter is deliciously crisp. But there is so much that it feels more like an ordeal than a meal. By the end, I'm reduced to squashing up the chips and concealing them under the surface of the tartare sauce. I even consider hiding a fistful in my napkin and slipping them into my satchel, but there are too many people around for this to be a viable option. Someone might grass me up to the waiter, and then I might be stripped of my honours at a later date. With the aid of a cup of tepid Yorkshire tea, I slosh the last few chips inside me. I feel like death, but I now have a certificate to put on my toilet wall, which I can gaze up at between rounds of vomiting. "Would you like anything else?" asks the waiter, sarcastically.

Back home, I'm still sneezing, and rather sceptical about the idea that eating like a pig will cure a cold. So I round off the day's toils with a wafer-thin mint. Unlike the man in the Monty Python film, I don't explode. Which is probably more of a relief for the upholstery than it is for me.