The big, fat problem at the heart of reality TV

There was an understandable backlash against the Channel 4 posters promoting the latest series of Big, Fat Gypsy Wedding, one of which I saw prominently displayed yesterday over busy road junction by Vauxhall Bridge in London.

The copy simply read: 'Bigger. Fatter. Gypsier.'

There certainly is a casual racism here, as we would never allow a similar jibe at another group which had its own distinct ethnic and cultural identity. I've been concerned in recent years by the readiness of younger people in the UK to use the term 'pikey' to describe someone or something perceived to be chav-like, trashy or dirty. Many probably don't realise that it's a racist and derogatory term for a gypsy.

There's another problem revealed by the bigger, fatter, gypsier line though and it's this: reality TV shows have to raise the shock bar with every new season. If the show weren't 'gypsier' than before, maybe we'd tire of it. It's the promise of something more extreme, more outrageous and more in-our-faces that is supposed to have us returning for another hour under the sunbed.

Remember Kim & Aggie, who cleaned up people's homes? They started with individuals who were dirty and untidy in season one and worked their way through to people who were clearly extremely unwell. Their participants needed support and medication rather the prying of TV crews and a splash of Dettol.

Gillian McKeith loved to demonstrate to people exactly how much junk food they were eating. Her early participants were shown their weekly intake laid out on trestle tables. It was shocking. But not quite shocking enough for later series. That's why she laid out 'dead bodies', constructed out of pork pies. And it's why she stuffed coffins full of ice cream. The ante needed to be upped if viewers were to get their fill the next time round.

And so it goes on. Big Brother, for instance, with more extreme and dysfunctional characters recruited each year. God knows what it's like now that it's moved channel.

I've watched these shows, so it would be rich for me to say they are exploitative and should be banned. But what starts as something mildly voyeuristic and within the bounds of decency can quickly become exaggerated and extreme. There is a boundary to be drawn somewhere. And it's probably between gypsy and gypsier.