Kindergartens should ban television-watching for toddlers and focus on "fun activities" to prevent them getting fat, according to an EU-funded survey into obesity prevention for four-to-six-year-olds.
Parents should also cut down on pre-school television-watching in bedrooms and unhealthy snacks in the fridge, a Greek professor leading a research project as part of a four-year study said.
Computer games should be restricted amid growing evidence that more youngsters have weight problems before they get to school age.
The ToyBox survey, the first phase of an investigation into how best to resolve the problem, found that obesity among European preschoolers is hitting record levels, with more than one in eight children overweight in northern Europe - rising to more than 25% in parts of southern Europe.
Nearly 40% of pre-school girls in Spain are now classified as overweight or obese.
ToyBox co-ordinator Yannis Manios, Assistant Professor at Harokopio University in Athens, said: "We need a new approach to prevent obesity."
The study, involving research in Belgium, Bulgaria, Germany, Greece, Luxembourg, the Netherlands, Norway, Poland and the UK, showed the need for better health-promoting policies targeted at youngsters.
"We found that many countries are lacking clear guidelines on healthy eating and active play," he said.
"However, there is good evidence linking sedentary behaviour, such as TV watching, with subsequent obesity.
"Therefore, TV watching in kindergartens should be replaced by more active, non-competitive, fun activities which will promote the participation of the whole class and help children to achieve optimal growth, health and wellbeing."
He went on: "Similarly at home, TVs in the bedroom and unhealthy snacks in the kitchen cupboard are a bad idea.
"Parents should also remember that their role is not only to provide healthy food and drink options but to act as a role model themselves, since kids are copying their behaviours."
The four-year research programme has a €2.9m grant from the European Commission, with a brief to "develop and test an innovative and evidence-based obesity prevention programme for children aged four to six years".