Tuesday: This year, along with the usual anticlimax/light deprivation New Year blues, there have arrived two specific causes for gloom: I am notably overweight, and I feel unusually slow-witted. To attack these twin depressants, I have developed a two-point plan: I will be spending most of each evening at my dartboard playing a game that permits me to indulge an ungodly talent for mental arithmetic; and tomorrow I begin a diet based on several of nature's finest anti-carcinogens - the prune, the carrot, Chinese green tea and limitless tandoori chicken.
Wednesday: This afternoon, someone told me that I have lost weight. This is odd. I only started dieting this morning. And yet, unlikely as it may sound, looking in the mirror perhaps I do notice the hint of a certain gauntness around the cheekbones. I must be very ill.
Thursday: Further evidence of sickness arrives when I notice a vivid red hue to the loo paper. "It's cancer, isn't it?" I ask Rebecca. "That's why I'm suddenly so skinny." She snorts and asks what I had for dinner last night. "You know what I had. Six pieces of tandoori chicken." "Six pieces of bright red chicken? And what," continues the Socratic examination, "did you have on them?" "Mint sauce." "Would that be the curiously red mint sauce supplied by the restaurant?" "So?" The familiar sound of the front door closing sharply sends me scurrying to the dartboard for consolation.
Friday: Examining myself in the mirror after my bath, I can identify what may well be the outline of a ribcage. I begin to look almost wasted. Panicky, I ring my mother. "I wouldn't worry," she replies sardonically when I ask if she thinks it is cancer. "You're hardly Mahatma Gandhi, are you?" I return to the mirror. She's right. I am more enormous than ever, possibly even clinically obese.
Saturday: In a Telegraph article about how fat British women are, there is a formula to determine obesity: square your height in metres, divide it into your weight in kilos, and if it comes to more than 30 you're obese. After supper I will sit down and work it out. With my facility for figures, it won't take long.
Sunday: It is 4.29am, and I am about to retire for a brief but, I suspect, troubled night. The A4 paper ran out six hours ago, but after using the blackboard next to my dartboard until the chalk was exhausted, I have calculated my score at 27.41 - well on the right side of obesity. That's if I squared my height in metres. If, on the other hand, I used the square root - and I've now rubbed off the crucial lines - then I'm twice the size of Ann Widdecombe. At this moment, it's very hard to be sure.
Monday: A friend rings up complaining of mild flu, but when I give her the standard prescription - bed rest, paracetamol, liquids - it transpires she is calling not to request advice but to give it. She has bought a book called Eat Right 4 Your Type by a Dr Peter J D'Adamo, whose theory holds that each blood type demands a different diet. Apparently this is how Martine McCutcheon lost weight. Although sceptical, I check the website, and when Rebecca returns from work she finds me at the table in front of plates of pickled herring, a bowl of fresh cranberries, breast of smoked duck, walnuts, a marrow and a Cadbury's Chocolate Orange. "Oh," she says when I explain, "and what blood type would you be?" "As you can see," I reply, waving an expansive hand before me, "I would be, indeed I am . . . um . . ." God have mercy, I do not know my own blood type. I never have. "So what the hell's the point of that disgusting smorgasbord?" I have not the first idea. Rising from the table in despair, I head for the sanctuary of my dartboard, pausing only to pick up the pocket calculator on the way.