The nine-year-old will eat no fat. Bacon, chicken, ham - the white trim always has to be painstakingly stripped off. Even then, he peers at the contents of sandwiches like a teacher checking for dirty nails. But the other day at breakfast his three-year-old sister spotted the crispy worms of discarded bacon fat on a side plate and scoffed the lot.

And so they licked the platter clean, you'll be thinking. But no - because my wife grabbed the three-year-old's wrist and said: “Don't eat those! Yeeeech!” She gave her a bowl of the new Rice Krispies instead (have you tried them? They don't snap, crackle or pop, but they're vaguely humanoid in shape and they have got “a natural pro-biotic”. Taste-wise, they're evidence in support of Roald Dahl's claim that breakfast cereal is made from pencil sharpenings).

As it was about eight minutes before the school rush, I bit back the urge to dispute the crispy-bacon-fat point. I thought it was great to see my daughter eating bacon, rather than the usual blandnesses: next stop, snails in parsley and garlic! Of course it isn't bad for a healthy, active three-year-old to eat some bacon fat. Quite the opposite. But when I sat down to try to work this out (it's always good to do some research in advance of a marital debate), I realised how complicated the question has become.

The problem begins, of course, with the modern belief that fat is bad, full stop. And that eating fat makes you fat, when it patently doesn't, any more than drinking alcohol makes you pick fights with lampposts. It just isn't that simple - but all the brainaching blether you're asked to absorb about fat, about saturates, trans-fats, lipids and hydrogenated vegetable oils makes it easier to settle for just fearing and loathing fats. You know where you stand.

We need fat to survive, of course - you're advised to get around a third of your daily calories from oils. But our guilt-riddled relationship with fat must be rooted in the fact that it's absolutely crucial to pleasure in food. Fat is taste, as all chefs and food manufacturers know. I know a meat scientist whose party trick is to serve up two lean pieces of fatless meat, one lamb, one beef, and ask his audience to tell him which is which. They think they can - but 50 per cent of them guess wrong. They don't enjoy the meat much either. Restaurants habitually buy meat that's far fattier than any supermarket would dare display, because the fat carries the flavour, and when it melts into the meat you say: “Yum.” That lovely, well-matured steak you ate at the French bistro - juicy, wasn't it? That was liquid fat. “Mouth feel” and “fat remodelling” - big conversation points in the sweet and snack design world - are all about the melting point of fats, and the way in which they'll coat your palate. Nice. New-style Rice Krispies, by the way, are 2.5 per cent fat as well.

We should all remember, though, that the last time the industry tried fooling with fat it came up with the idea of hydrogenating the stuff - and so invented trans-fats, which they stuffed in cakes, spreads and sweets. Trans-fats were last summer's great fat scare - “more dangerous than any other hitherto known fat, saturated or not!” Some nutritionists said that, in fact, butter might well be healthier than trans-fat margarine. Oops. Anyone born in the Sixties or Seventies should now be suing the food scientists for all those childhood parties and picnics spoilt by Flora and Stork.

I wonder if it's possible to swing the food scare pendulum and start an “Eat fat - it's great!” movement. Probably not. For now, I'll go on keeping the bacon fat to fry my skinny son's fish fingers in (strange how tasty he finds those, hee-hee). But I'm beginning to wonder just what the obesity rates are among the children of middle-class, eco-obsessed foodie dads?

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