I could tell he was hoping we really would all be engulfed by a black hole emanating from a Swiss mountainside, which would lead to the intriguing result that Switzerland had produced the cuckoo clock, lots of secretive but extremely boring bankers, and the end of the planet. In his mind this would give him several days of a hedonistic teenage existence, unlimited computer and internet access accompanied by industrial quantities of sweets and fizzy drinks. After all, if the world is going to end, why be restrained.

That's why teenagers have mothers - to stop them being totally stupid.

Without the license to behave irresponsibly he kept on doing his homework, eating sensible food, and living a reasonably restrained life. Writing a story like this illustrates how tempting it is to do crazy stuff when it's possible we might not be held accountable.

Isn't that often the way with weight loss?

* Sneak that extra cookie because no one is looking.

* Have the chips rather than the salad because it's Friday (and Saturday and Sunday).

* Eat the extra slice of cake you made otherwise it'll go stale.

We pretend that these actions are justified. One extra cookie won't count. I'll have that bar of chocolate at the weekend. It's not good to waste food. But what we are really doing is not being accountable. Not being accountable to your slimming club or your nutritionist or your loved ones. But above all not being accountable to yourself.

The world will not end with the Large Hadron Collider. (I can say that with confidence because if the world does end you won't be reading this newsletter.) My son has no excuse for not doing his homework because, however much he hopes for it, his maths teacher is not going to disappear into a black hole.

And you have no excuse for not eating well because however much you hope for it, excess calories will always turn into fat.

It's easy to think "I'll start the diet tomorrow" or "One cookie won't hurt" or "Nobody will know if I have this snack".

But don't let your mind become a black hole of excuses. Don't let your digestive system become a black hole for food - engulfing everything it encounters. Don't let a Swiss chocolate mountain end up on your hips.

Tell yourself - "The world will not end tomorrow but I'll still have this excess fat. So I'm making choices today so I can be slim tomorrow".

And happy (and healthy) eating.