Katy Guest: Shame on a doctor who leads teenage girls to eat badly

There was an alarming story in last week's papers about the findings of a Department of Health report on eating habits. The UK National Diet and Nutrition Survey found that teenage girls "are condemning themselves to a lifetime of ill health by eating less than three servings of fruit and vegetables every day," said one newspaper. "They are also shunning meat, depriving themselves of essential nutrients ... and eating far too much saturated fat."

Later in the same edition, the paper continued its week-long promotion of this summer's latest fad, the Dukan Diet. This revolutionary new idea (which seems remarkably similar to the Atkins Diet, only more hardcore), encourages rapid weight loss by cutting out all fruit and vegetables and eating only low-fat meat, fish, eggs and dairy. This primary, "attack" phase lasts between one and 10 days, until target weight is reached. "Many people can expect to lose as much as 7lb in five days", it is claimed, as if this were in some way good.

Dr Pierre Dukan, the French dietician whose book has sold more than 10 million copies around the world, recently lost a libel action against another doctor who called him a "fraud" and claimed that his diet carried "grave risks", so I feel relatively relaxed about saying that this is horrific. Nothing should make a person lose half a stone in less than a week except for being quite ill, which funnily enough is how this "attack phase" will make you feel. Drawbacks include flu-like symptoms, bad headaches, nausea, lethargy and inability to concentrate, as well as bad breath, a metallic taste in the mouth and a powerful odour to the urine.

Apparently, "You should welcome [these] as proof of success." In the longer term, high protein diets are linked to gout, and cutting out the vitamins that are found in fruit and vegetables can cause problems with bones, teeth, skin, hair and pregnancy. Rapid weight loss is also continually proven hardly ever to last – and usually to result in net weight gain.

Later phases of the Dukan Diet involve reintroducing vegetables, and you're also allowed the odd spoonful of oat bran to combat the seemingly inevitable constipation. None the less, it has been criticised by the food safety agency in France, and the British Dietetic Association has called it one of the Top Five Worst Diets of 2011. The Atkins Diet is similar, but allows its victims to eat any meat and dairy products, putting them at risk of eating far too much saturated fat – by which sin, you'll remember, Britain's teenage girls are condemning themselves to a lifetime of ill health.

Teenage girls have a lot to learn and remember in that lightning transition phase from little angel to cause-of-all-ills, so you can understand why they're confused by all these mixed messages. Trust me: you can bang on all you like about reacquainting yourself with vegetables and drinking iced water until it comes out of your ears, but the one thing that teenagers will hear is "get thin quick by giving up anything nutritious". Honestly, do you know any adults who are maintaining an ideal weight after sensibly following one of these diets long term, or do you know several people who occasionally eat nothing but cheese for a week and then treat themselves to a doughnut for being so good? If adults find it impossible to carry off weight loss in a controlled and healthy way, then allowing these weird fad diets near confused and vulnerable teenagers is almost criminally irresponsible.

If I could talk to all the teenage girls in Britain, I'd like to tell them that they're being conned. They're told that they're too fat, and too thin, and eating all wrong and burdening the National Health Service. And then they're sold a diet that will make them feel poorly and miserable as quickly and surely as it makes some Frenchman rich.

Almost any diet, followed to the letter, will make a person lose weight. But what's the likelihood of following a diet like this indefinitely when you're constipated, smelly, exhausted and nauseous, and you can't even have a sandwich or look forward to a vitamin? Considerably slimmer than a dieter's bum. Cut out the middle man, and the oat bran and the gout, and save yourself the money and the stress. And as an additional bonus, you won't even have to pong.

Hurrah for Henry! Horrid heroes are best

Hats off (with frogs hidden in them) to Horrid Henry, who makes his film debut on Friday after 17 years of inexhaustible naughtiness. Based on the books by Francesca Simon, the film will star Anjelica Houston, Richard E Grant, and Mathew Horne, Gavin from Gavin & Stacey, as Henry's dad. Apparently, it sees Henry join forces with Moody Margaret and his insufferable brother Perfect Peter, although anyone who knows Henry will find this a bit hard to believe.

Henry is the latest in a long and noble tradition of naughty boys and girls who have caught children's imaginations. Is there anyone who grew up wanting to be Walter the Softie rather than Dennis the Menace, or who sympathised with William Brown's sister, Ethel, or wished that the St Trinian's girls would wear longer skirts, or that Nigel Molesworth could spell?

Even good girls and boys – especially those – love a rebel. A true children's book hero rejects authority, but his own moral code is fundamentally more sound than those of power-deranged teachers and prefects and despicable maiden aunts. A Horrid Henry is sharp-witted and stands up against a corrupt system. Sometimes, grown-ups, it's good to be horrid.

I think you’re amazingly creepy ...

Some people naturally listen to the words of songs, and some do not – which is why some people are fans of Joni Mitchell, while others end up having an "our tune" that's all about a break-up or a stalker.

As a words person, I find some of the most popular songs intensely annoying, including this summer's hit from Bruno Mars, "(I Think You're Amazing) Just the Way You Are". I can't help but imagine the poor girlfriend, who asks, "Do I look OK?", only to face a hysterical monologue about how she is perfect and must never change. "Nope, I was right," she must say, "I have pasta sauce all down my top. I'll just go and change." He'll sob, "Don't change!" ever more desperately, and they'll never be able to go out. It sounds like a nightmare.

There’s no such thing as a media

Although the Murdoch scandal has given us the marvellous word "schadenfreugasm", the damage it is doing to the English language outweighs the benefit. We've seen weasel words from politicians and police, and some slippery semantic games played with "hindsight", "humble", "appropriate", and "defenceless 80-year-old man". But the expression that makes my hackles rise is "the media is ...".

The word media is the plural of medium, which is a means of conveying a message. Words are powerful, and we should beware their manipulation by people who should know better. Those in the wrong would love us to believe that "the media" is one beast which thinks and does and cheats as one.

We should all remember that the media are just lots of little means of conveying messages. This message is: mind your language.