I AM an addict. A secret addict. A two-faced lying cheat.

And if you are a mum or dad, I bet you are too.

If you are reading this and you know any of my children, you must take an oath not to tell, or to show them this  column.

Because I started out planning to write about new evidence this week on the contents of school packed lunches (full of crisps, sweets and sugary drinks).

I could sit here and honestly pontificate about how I make lovely healthy packed lunches for my son. And it would be true.

And I could also tell you how I bring frozen lunches for myself into work which are health-freakily, vege-luscious (quinoa, miso, tofu, tahini, Japanese seaweed, pulses, seeds, nuts... I love all that stuff).

I rarely buy crisps, biscuits or cake at the supermarket. None of that rubbish in my fridge or larder. I am a paragon. A green goddess of good food habits. Ask my kids.

But the thing my children don't know is that as soon as I get to the office it's one long pig-out zone for the sugar junkie, food schizo that I really am.

First of all there's the office vending machine. I can happily say 'no' to crisps and fizzy drinks. But all day long those chocolate bars are calling my name. Yesterday I had a Twix. I don't even like Twix. I like pure chocolate with no bits of biscuit or toffee getting in the way of the sticky melt-in-the-mouth sensation. But I pressed number 32 instead of 34 and a Twix fell out.

At 11am the nice man from the bakery at Barton comes in with trays full of cakes and sandwiches.

Yesterday I had a giant doorstep brown bread cheese ploughman's. I told myself it was healthy, and it probably would have been if I'd just finished ploughing 10 acres, but it was completely unnecessary for a sedentary office worker at 11am.

Then there are the office cakes. I can't really explain the office cake phenomenon but I'm given to understand it's not just the Herald Express.

Children. Don't believe your parents. Whatever they tell you about work: how tiring it is, how important they are, how they slave to pay the bills.

The truth is they go to the office for one reason and one reason only... to cram their gobs with cake all day long when you can't see them.

Take this week. It was an ordinary week. Nobody's birthday or anything. But on Monday morning there was a pack of giant chocolate muffins just sitting there waiting to be opened. I don't know where they came from or who paid for them. It certainly wasn't me. I don't buy unhealthy packet sugary rubbish (I just eat other people's).

I held off until about 10am and then succumbed. I even had the cheek to complain as I ate it, about how muffins look big and fat on top, but when you peel off the paper case the actual cake content beneath is tiny, like the mushroom cloud of Hiroshima.

Yesterday was supposed to be a cake-free day. But then somebody remembered an out-of-date chocolate cake which had been in the fridge from Lin's 51st birthday cake sensation last Friday (I wasn't there but apparently it was an all-day-long cake-feeding frenzy).

So we decided to have the leftover cake for elevenses. It was lovely. One of those fudgy cakes which improves with age by getting squishier and chocolatey-er.

I ate it as a prelude to the cheese ploughman's doorstep, which was bigger than my entire head.

I have yet to tell you about the infamous newsdesk cookie tin.

Magically that tin never runs out of biscuits, despite the fact all day long there's a trickle of people trying to find a legitimate pretext for hanging about near the newsdesk just long enough to look natural while they help themselves to a biscuit or two during any five-minute interval which may occur between the cake eating and the actual pretence of good nutrition which is the actual lunch eating.

The person who sits next to the biscuit tin is also a mum and we all suspect it is she who spends half her wages keeping it secretly topped up.

She tells me she never buys cakes or biscuits at home, because her three strapping sons are also under the illusion that mum thinks biscuits and cakes are unhealthy.

Which all brings me to the original idea for this week's column. I was listening to Radio Four on Monday morning as I was making my son's very, very healthy packed lunch (actually it was just an ordinary egg sandwich, yoghurt and grapes).

But the news was about how schoolchildren's packed lunches are failing to meet nutritional standards.

In the first study of its kind, the Radio Four voice said, pompously, only one per cent of lunches were found to meet nutritional standards.

And they interviewed Prue Leith, chairman of the School Food Trust, to discuss this national scandal.

I think she said head teachers should gradually and sensitively work with parents to ban junk food from packed lunches.

And maybe she's right. But when I looked on her website even she admits: "I'm seriously greedy. I will go to the grave wishing I was a stone lighter (right now I wish I was a stone and a half lighter).

"But I simply refuse to eat salad without dressing, or strawberries without cream, or boiled eggs without toast soldiers.

"I once wrote a diet series for the Sunday Times. It worked fine — dozens of readers told me how much weight they'd lost.

"But I couldn't follow it! It had portions for men and portions for women and I was fine on the men's allowance."

And how about Jamie Oliver? I really admire the passion with which he tackled the problem head on in his Jamie's School Dinners series on the BBC. But let's face it, he likes his food too.

It's hard trying to teach kids about healthy eating when we've all got our own secret food issues.