What is "junk food"? Everyone will have a different view - and I mean everyone. The answer, even from authoritative sources, will be waffle, proclaimed confidently but with contempt. "Junk food" has become a pejorative term.
Even the Oxford English Dictionary's definition is incomplete: "pre-prepared or packaged food that has low nutritional value." To which the Chambers Dictionary adds: "easily available and quick to prepare" - which compounds the confusion.
Why on earth should we condemn food with low nutritional value by calling it "junk"? Some such foods are harmless and, possibly, enjoyable. And "quick to prepare"? Far from condemning this, we should praise its enormous advantage to most households.
Medical opinion, too, is confusing. For instance, it says it is "addictive", which puts it on a par with drugs - a crass exaggeration.
The fount of medical findings, the Lancet, severely berated celebrities and BBC children's television programmes for promoting "junk food" (without defining the term - which is impossible), and last November called for a ban on celebrities endorsing unhealthy food, and for a ban on advertising such products during children's TV programmes.
Unbelievably, some primary schools have actually banned soft drinks from lunch boxes, without very much more convincing data. This is going to ridiculous lengths. We might as well ban motor racing because it promotes speeding, or rugby for promoting brawls.
The confusion deepens. Tessa Jowell, the culture secretary, called for a ban on advertising junk food and soft drinks last year. Yet Ofcom, the media watchdog, ruled out such a ban last month, recommending more exercise, better family eating habits and food labelling. But Jowell vowed that she hasn't given up yet.
My own view is simple: junk food is rubbish and you shouldn't eat it. But then, which foods are "rubbish"? This can only be defined negatively: if what you eat or drink tastes good, is made of fair-quality raw material prepared with reasonable skill, at absolutely every level of consumption and prices, then most certainly it is not "junk food", and anything contrary to that - to me, at any rate - certainly is.