Health experts have attacked an advertising campaign encouraging children to eat a McDonald's meal every day for four weeks. The campaign, launched today, urges people to collect 28 plastic Snoopy figures by buying an 'extra value meal' each day until October 8. 'Try to collect them all, because missing even one makes a very big difference,' says an advertisement placed by the fast-food chain. The promotion, expected to reap more than $12 million in doll sales alone, follows a spectacularly successful Winnie the Pooh campaign in June, which sold out in days instead of the designated five weeks. Nutrition Association president Dr Susan Lui Sau-han said the campaign could see hordes of children wanting the meals - a burger, french fries and soft drink - every day until next month. 'This is a marketing technique - they want to draw children - but as a dietician, this is not a balanced diet,' she said. 'It can be creating a problem for parents, who want to educate kids to have a balanced diet, but the kids want to have the toy. It's not a very encouraging policy.' Peer pressure at school would encourage children to collect the dolls, she said. Burgers and french fries were high in fat, while soft drinks were high in 'empty sugar calories', Dr Lui said. Such a diet would lead to digestion problems and vitamin deficiencies. 'Once children tune in to sweet, high-fat food, they get used to it,' she said. Chinese University paediatrician Dr Gary Wong Wing-kin said Hong Kong children were bigger and heavier than ever and were getting fatter. If children ate an 'extra value meal' every day for a month they could gain nearly a kilogram, Dr Wong said. 'The problem is if a child gets used to a high-fat diet, over five or 10 years it will have a significant impact,' he said. 'I hope we're not going the way of Singapore, where they've seen a dramatic rise in coronary heart disease, heart attacks, high blood pressure and diabetes in young adults.' McDonald's marketing director Shantel Wong Lai-mun said more than two million Snoopy dolls would go on sale from today, priced at $6, with each $17.80 meal. 'With the experience of Winnie the Pooh, we've ordered more dolls,' Ms Wong said. If people agreed with the company that this was a cute and lovable collection and wanted to collect the whole set, they would be welcome to come in every day, she said.