Move over Ryanair, there's an airline with its sights set on taking the title for the most cunning ways to bump up the price of a ticket.

Air France KLM has hit on the cunning rouse of charging obese people extra, by making them buy a second seat on the plane.

From April 1, they will generously give them a 25% discount, but will demand the overweight buy an extra seat. They say anyone refusing to buy two seats will be turned away at the plane door.

This isn't the first time the airline has had a bash at this. In 2007 they charged a passenger as he got on the plane. In that instance they were taken to court and the judge ruled they couldn't do it, because the rule wasn't in the small print.

Now they are changing the small print, and fatties will have to pay up.

Is this fair?

Fatism is the only socially acceptable form of discrimination. Victimising those carrying a few extra pounds is practically a national sport, so it didn't come as a huge surprise when Ryan Air proposed a 'fat tax' for obese passengers today.

Apparently, a survey found one in three passengers supported the idea of charging fat people more, on the grounds it takes more fuel to fly their bulk.

This raises the spectre of a humiliating weigh in at check-in – which we could all live without. But that's not the only problem. Since airlines were forced to add in any unavoidable charges when advertising the price, there has been a rash of 'optional' extra charges introduced.

This is clearly set to be the next, but there are five others to beware of.