On the bouncy play platform outside Ghent's 15th century slaughterhouse, the banana was thumping the beefsteak.

The two boys battled in the drizzle yesterday, the one in the fruity yellow costume serving up another veggie victory over his rival in bloody scarlet.

The parent onlookers laughed and munched another soya fritter. Mmm, yummy, said the man with a heart condition. They queued five-deep in the rain to dip their organic, wholegrain bread in the aubergine caviar, to smear their lips with eggless mayo. Another pure fruit vitamin cocktail under the marquee?

"This is pretty special, pretty unique," said Tobias Leenaert, an anti-meat campaigner. "An entire city proclaiming one day a week a veggie day."

Ghent embarks on a radical experiment today, seeking to make every Thursday a day free of meat and of the fish and shellfish for which the city is renowned.

On the eve of what is being touted as an unprecedented exercise, the biggest queue in the Flemish university town of 200,000 yesterday was for signatures – to collect a bag of wholefood goodies and sign up for "Donderdag – Veggie Dag", turning the burghers of Ghent into pioneers in the fight against obesity, global warming, cruelty to animals and against the myth that meat-free eating amounts to a diet of soggy lettuce, a slice of tomato, and a foul-tasting bean burger.

The city council says it is the first town in Europe and probably the western world to try to make the entire place vegetarian for a day every week. Tom Balthazar, the Labour party councillor pushing the scheme, said: "There's nothing compulsory. We just want to be a city that promotes sustainable and healthy living."

Every restaurant in the city is to guarantee a vegetarian dish on the menu, with some going fully vegetarian every Thursday. From September, the city's schools are to make a meat-free meal the "default" option every Thursday, although parents can insist on meat for their children. At least one hospital wants to join in.

A small, dreamy city of spires, bicycles, and canals, prospering since the Middle Ages, Ghent may be on to something. It appears to be tapping into a zeitgeist awareness of the cost to human health and the environment of intensive meat and dairy farming. Other towns in Belgium and the Netherlands are making inquiries; there has even been one from Canada.

"We hope that the university, other institutions, enterprises and other towns will jump on the train," said Leenaert, director of the local branch of Flanders' Ethical Vegetarian Association (EVA).

The organisers cite UN data arguing that meat production and consumption are to blame for 18% of greenhouse gases – more than cars. "If everyone in Flanders does not eat meat one day a week, we will save as much CO2 in a year as taking half a million cars off the road," said the EVA.

"I never touch meat, unless I'm at my grandmother's and I need to be polite," said Karien De Temmermann, a young EVA member.

"This is not a plan for everyone to be forced into vegetarianism," said Wim Coenen, a vegan who works as an importer of vegetarian pet food from Italy. "But it will reduce our carbon footprint. The basic premise is to introduce a way of lessening our meat consumption."

The revolution starts today with a foodie festival at the vegetable market. Ninety thousand town maps listing the best eateries for the meat-shy are being handed out. Recipe booklets and food samples are being distributed, with fair trade wine to wash down the nibbles. A nearby restaurant is serving a four-course veggie lunch for €12. The kebab house on the market is eschewing the doner for broadbean falafel and haloumi cheese.

Ghent boasts a string of outstanding restaurants and is well-known for gourmet vegetarian cuisine. The council reckons it has more veggie eateries per capita than London, Paris or Berlin.

The Lib-Lab coalition running the city was persuaded to back the idea when Philippe van den Bulck, an outstanding culinary talent, served up a veggie gastronomic tour de force at the town hall. He is one of Flanders's top chefs and food writers, doing time at El Bulli in Spain, to many the best restaurant in the world. He is also a vegetarian.