I can tell you to the second exactly what I was doing last Thursday at 1.25pm.

I was eating a jacket potato filled with half a tub of cottage cheese (low fat variety), and a small side salad, minus dressing.

What was I doing at 4.30pm? I've no idea but if you wanted to know what was happening one hour and ten minutes later I can certainly let you know. I was removing the bones from a freshly grilled trout, served with broccoli and three mushrooms.

And at 10.30 that evening . . . ? Just a minute, I'll have to check my new diary. Ah, yes, I drank a cup of low calorie cocoa - and ate a tin of sardines.

Yuck! I can't have done, but I must have if it says so here. My diary never lies - it would be defeating the object of the exercise if it did.

The object of the exercise is to record every mouthful of food and drink that passes my lips. What I do in-between meals is of no interest.

I could win the National Lottery (as I never buy a ticket that is, I admit, unlikely), be given my own TV show, have dinner with Prince Charles. You would find no mention in this diary.

I've been keeping it for three weeks now and I can honestly say that, as diaries go, this one is definitely not on a par with Samuel Pepys's fascinating observations, yet, in its way, it is equally candid.

Every grape, every mouthful of coffee, is faithfully recorded, not for posterity but for the eyes of Nurse.

Nurse is my physical antithesis, tall, slim and fit. She inhabits an office at my doctor's practice and it is she who has decided I should keep a daily food diary, which she will read.

It's all part of the anti-cholesterol battle I am now waging in an effort to prolong my lifespan. I have two stones of excess weight to lose and Nurse is providing encouragement to keep my suicidal cravings for chocolate and cheesecake at bay.

She reads my diary, we discuss what I've eaten in the past week and I make excuses for the lapses - tins of sardines at bedtime and the like.

The diary is meant for Nurse's eyes only but others, well, one other in particular, have also read it.

"So," says The Mother, "according to your diary you had two low fat yoghurts after I'd gone to bed last night. That was a bit greedy, wasn't it?

"And it says here you had two pieces of toast and a bowl of cornflakes at midnight on Friday."

"That's confidential," I say. "You shouldn't be reading my diary."

The Mother ignores this. "It's a bit pathetic having to write down everything you eat because you can't trust yourself around food if you don't," she says.

"All I've ever needed is will power. You can say no to anything if you're determined enough."

On Monday morning The Mother finds a second diary I've left in the kitchen.

"What's this?" she asks.

"That," I tell her, "is your diary. It's to help your will power."

"My will power doesn't need any help, thank you," she snaps.

"Really?" I say. "Just read this then. Sunday: 8.15am, coffee and cigarette; 9am cigarette; 9.45am cigarette;

10.30am cigarette (and coffee); 11.45 am cigarette . . ."