I've spent my entire life counting: 80 calories for the egg, 15 for the scrap of butter... it's so bloody tedious, time-consuming and unhealthy when you're obsessed with food. The moment you think 'I can't have that', even a steaming dog turd becomes what you most want on earth.

Since I wrote Does My Bum Look Big In This? I thought 'Christ, here is the irony. I've wanted to be thin and gorgeous all my life and my fortune comes from the fact that I am as I am.' Now I have an incredibly unhealthy diet, well, not unhealthy, just not regular. I have no aspirations to be a domestic goddess any more than Nigella does. She's no bloody earth mum. That's like saying Tom Cruise is madly in love with Penelope. I used to love cooking but now I've got two kids I would kill for a cook. I do a bit of cooking on my new sitcom, Posh Nosh, but it's really about my relationship with my gay husband (Richard E. Grant). I still do that 'I'd be a better person if I hadn't had those five chocolate biscuits', but everybody lives in that world. I know I'll go to my grave being the bum girl and, for now, that's fine with me.

Arabella Weir is supporting Red Nose Day 2003. For a fundraising kit call 09065 500 500, www.rednoseday.com

The week at a glance: guilt, guilt and more guilt

Breakfast: This is a regular. I have a banana with organic bio yoghurt and prunes. Two Earl Grey teas with sweetener.

Lunch: 10 mini sausages, crisps and iced Barbie birthday cake because it was my daughter's fifth birthday. Three glasses of wine.

The party went through to 7pm, so I didn't eat after that. Three glasses of water.

Breakfast: Same.

Mid-morning: dregs of my boyfriend's espresso.

Lunch: Bagel and ham with tomatoes and cucumber. Low-sugar cranberry juice.

Afternoon: Five chocolate finger biscuits with tea.

Evening: Prawn and noodle stir-fry.

Breakfast: The usual.

Lunch: At the Sugar Club. Usually lovely, but I picked a foul curry dish.

Dinner: I had the remainder of my kid's supper: old bits of fish finger, chips, and, later, half a panatonne with tea.

Breakfast: The usual.

Lunch: My staple of carrots and hummus, but absolutely without bread because I try not to eat bread in the day.

Snack: Tea with an oat cake.

Dinner: Organic pork sausages, which my kids hated, with rice.

Breakfast: The usual.

Lunch: Cheese and ham sandwich (for some mad reason I thought I deserved it).

Dinner: Got back from my daughter's school depressed. I was having an 'Oh God, it's not worth living and I'm going to eat everything...' so I had three packets of crisps, half a bottle of wine, my kids' chips and cheddar cheese.

Breakfast: An unprecedented toasted bagel which, in my mind, I'm not really having. I eat bagels, when I think I'm not going to eat anything.

Lunch: Tomatoes, tuna and sweetcorn, all eaten out of the tub because I felt guilty about the bagel. Then finished off my kids' pizza.

Dinner: Prawns, spinach and noodles. Water.

Breakfast: Bagels, again.

Lunch: Went to a local north London restaurant, Banners. I had seared tuna with a Greek salad. Don't ask. I really wanted a pudding but I didn't have one. Glass of water.

Afternoon: A girlfriend came for tea and we had pannatone.

Dinner: Decided I had to be more healthy and brilliant so I had pan-fried salmon and spinach.