Friday 31 March

9st 5lbs, cigarettes 20, alcohol units 0, calories 1500

How can I have put on 3lbs since the middle of the night? I was 9st 4 when I went to bed, 9st 2 at 4am and 9st 5 when I got up. I can understand weight coming off - it could have evaporated or been passed out of the body into the toilet - but how could it be put on? Could food react chemically with other food to double its density and volume, solidifying into ever heavier hard fat? I don't look fatter. I can fasten the button though not, alas, the zip on my '89 jeans. So maybe my whole body is getting smaller but denser. The whole thing smacks of female bodybuilders and makes me feel strangely sick.

I look wistfully at my colleague Perpetua, her vast bulbous bottom swathed in a tight red skirt with a bizarre three-quarter length striped waistcoat strapped across it. What a blessing to be born with such Sloaney arrogance. Perpetua could be the size of a Renault Espace and not give it a thought. I have never heard her so much as enunciate the words "fat unit". How many hours, months, years have I spent worrying about weight while Perpetua has been happily looking for lamps with porcelain cats as bases around the Fulham Road? She is missing out on a source of happiness, anyway. It is proved by surveys that happiness does not come from love, wealth or power but the pursuit of attainable goals, and what is a diet if not that?

I call up Tom, who says write down everything you've eaten, honestly, and see if you stuck to the diet:

Breakfast: hot-cross bun (Scarsdale Diet - mild variation on specified piece of wholemeal toast); Mars Bar (Scarsdale Diet - mild variation on specified half grapefruit).

Snack: two bananas, two pears (switched to F-plan as starving and cannot face Scarsdale carrot snacks). Carton orange juice (Anti-Cellulite Raw- Food Diet).

Lunch: jacket potato (Scarsdale Vegetarian Diet) and hummus (Hay Diet - fine with jacket spud as all starch, and breakfast and snack were all alkaline-forming with exception of hot-cross bun and Mars - minor aberration).

Dinner: four glasses of wine, char-grilled tuna with polenta crust (Scarsdale Protein Diet, and also Hay Diet - protein-forming); portion tiramisu; Peppermint Aero (pissed).

I realise it is has become too easy to find a diet to fit in with whatever you happen to feel like and that diets are not there to be pick and mixed but picked and stuck to, which is exactly what I shall begin to do, once I've eaten this croissant.

Saturday 1 April

On the way to meet Sharon and Tina for shopping, an old couple, plainly up from the country for a new jar of marmalade, got on the Tube and two young girls wearing flared jeans and Doc Martens gave them their seats. Well! The girls didn't know what to do with their mouths and no one in the carriage knew where to put themselves. It felt as though someone should shout, "OH FOR HEAVEN'S SAKE", or everyone should turn and shake hands with each other like in church.

Next thing I found myself fantasising about men giving ladies their seats, especially, say, on a Friday night after work. We would feel so cherished and they would feel kind, strong and good about themselves.

Naturally, I brought the worrying fantasy up with the girls. "Of course they should bloody well give up their seats," exploded Sharon. "They sit there surrounded by seatless girls carrying eight Tesco Metro carrier bags each, and it has been proved by surveys that they will go home and have supper cooked and washed up by some woman who's been working just as hard all week and stood up on the Tube all the way home carrying shopping. It's positively third world. We learned how to go out and earn our own livings and still carried on making the supper and cleaning behind the toilet and they didn't learn how to cook, forgot how to put shelves up and mend cars, and abandoned giving up their seats."

"We're a doomed sub-species, doomed," I said.

"No," said Sharon. "We're going to take over the world while they sit watching football in their vests throwing beer cans at the television. We'll just kind of keep them as pets. For sex."

"In your dreams," said Tina.

When I got home there was a message from my Dad asking if I would meet him for lunch on Sunday. I went hot and cold. My Dad does not leave messages for me. My Mum leaves messages for me. My Dad does not come up to London to have lunch with me on Sundays. He has roast beef or salmon and new potatoes at home with Mum. "Don't ring back," he said, "I'll just see you tomorrow." But I'm seeing Daniel tonight and we won't even be up by ...

Sometimes I realise how vile and selfish I have become, almost like Cruella De Vil in 101 Dalmatians. Poor kind, sad, uncommunicative Dad. I go out to for cigarettes and try to work out what the hell is going on, get used to the idea of looking after my parents instead of them looking after me and fight off existential despair.

When I get back, the light is flashing on the answerphone.

It is Mum, saying she is coming to see me for lunch tomorrow. She will bring a piece of salmon with her and will be here about 1 o'clock.