Diets make you lie, they take your money and your friends, says Sarah Vine. But like a bad boyfriend, we go back to them. Wisdom from a woman who knows...

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1. They make you lie

Mainly to yourself, but also to friends and family. As in, Friend: "How's the diet going?" You: "Really well, actually. I mean obviously it takes a bit of getting used to, but now I find I really look forward to my kale smoothie first thing in the morning." Translation: "It's miserable, but I'm damned if I'm going to admit it. The kale smoothie is like drinking a swamp. Even the dog won't touch it, and he eats guinea pig poo."

2. Only single people with large disposable incomes and no known dependants can successfully follow a diet

It's late, I'm tired, the kids are killing each other, my husband's at work, I'm still on deadline and I just need something to keep me going. Open the fridge: an array of leafy greens and purple tinged anti-oxidant style vegetables. I should really slow roast some sweet potato in coconut oil and mixed seeds. Instead I'm going to eat half a block of the kids' cheddar. And crack open a can of Coke Zero.

3. However much weight you lose, you will never actually be happy

I have been everything from a size 10 to nudging an 18. I even once, in about 1984, got into a size 8 at Miss Selfridge. But no matter how big or how small, I can honestly say that I have never been comfortable in my skin. Except when I was pregnant, when I had permission to be fat. Sometimes it's not a diet you need, but a shrink.

4. A dieter and their money are easily parted

Do I really need to explain this one?

5. Life without bread is almost not worth living

Bread, it turns out, is the most addictive substance known to humanity. That is because it is the most delicious substance known to humanity. This you only know when you have to learn to live without it as a result of it also being the most fattening substance known to humanity, especially if you have a thing for it toasted, dripping in hot butter and Marmite.

6. Beware the plateau of deadly temptation

You know how it is. You've been doing so well. You've seen a few results, you've dropped a couple of pounds. You keep buggering on. You lose a few more. Then, just at the point where you're starting to wonder whether there might not be more to life than roast quinoa, the  bloody diet stops working . Now you're eating dust and you're still not getting any thinner. "Oh go on," a wicked voice whispers in your ear, "Have a slice of carrot cake, you might as well." This is known as the Plateau of Deadly Temptation, and very few get out alive.

7. The only thing you're guaranteed to lose is your sense of humour

The human brain is hardwired to hunt and gather, and there's something about having to resist that primeval urge in Maison Blanc that seems to put us in a monumental grump. You know that whippet-thin woman at the school gates with a permanent frown and two terrified children? She's hungry. Really, really hungry. So hungry she'd eat one of them if she thought she could get away with it. She'd be SO MUCH HAPPIER if she gave in and had a yum-yum. Or three.

8. The first thing that shrinks is your brain

Seriously. Concentrating while on a diet is incredibly hard. The brain feeds off carbohydrate. So it's practically a scientific fact that cake makes you cleverer.

9. Dieting ruins your social life

You can't drink, you can't eat. In fact, life is so bloody miserable all you want to do is go to bed at 9.30. When you do manage to see your friends, you just annoy them either by a) having lost weight or b) refusing to eat the food they've so lovingly cooked. And because alcohol is the biggest calorific offender, you're also sober. And therefore almost certainly no fun whatsoever. Before long, they may start to wonder why they ever liked you in the first place. Once again, your only true friend is a tub of dulce de leche.

10. The only thing that's certain is that you will have to do it all again. And again. And again...

On their own, diets don't work. They may alleviate the symptoms (fatness) but they don't address the underlying cause of the problem. You have to take a holistic approach to weight loss. Unless you're one of those lucky few who never put on weight, staying a healthy weight is a lifestyle choice. For someone like me, it's akin to being an alcoholic. Every morning I have to wake up and say "My name is Sarah Vine and I am an over-eater". Like an alcoholic, it only takes one lapse and I'm back on the sauce. This is exceptionally boring. But true.