Teachers should sit down for an Italian-style meal with their pupils every lunch hour, say experts.

The adoption of the dining experience as part of an extended school family would mean the end of packed lunches and pupils being allowed out to buy their own food.

But researchers say giving pupils at both primary and secondary schools one hot meal is the only way to improve their health and social skills. The only drawback is that the quality of meals served up can no longer be guaranteed as food and fuel prices rocket.

Teacher representatives say the practicalities of the sit-down meal are limited as teachers take on more duties in their own time. It is also likely that schools will become responsible for promoting healthy eating in schools under a new Wales-only law this September.

But in written evidence given last week to the committee scrutinising the measure, the National Association of Head Teachers (NAHT) said the new duty would make heads accountable for a service they have no control over. It also says moves to vet what parents put in lunchboxes would be wrong.

Kevin Morgan, professor of European regional development at Cardiff University, believes parents and children could be converted to the idea of an “old-fashioned” sit-down meal with better consultation.

Based on research in other countries, he says it is the way Wales should be heading. But he agrees quality is a problem.

“The costs of labour, fresh food and cooking have gone up, while take-up levels of school dinners are collapsing,” he said.

Wales has often been accused of lagging behind the other home nations in devising healthy eating plans for schools, despite having one of the highest rates of childhood obesity in Britain. Unlike Scotland and England, there are no national nutritional guidelines in Wales for school dinners.

This September, the Assembly government will pilot different school dinner arrangements, based on research, in four Welsh local authorities. But the project will take about two years to complete.

The government’s 2006 Appetite for Life report came out in praise of sit-down meals and an end to the grab-and-go lunch in schools.

The growing trend for packed lunches, or pupils going out for lunch, is increasingly said to result from schools adopting healthier menus with less choice.

But last month, inspection body Estyn reported that one major reason for children refusing school dinners was to avoid being separated from their friends who ate outside, fuelling calls for the sit-down approach.

There also seems to be a growing stigma attached to having free school meals, according to the report Food and Fitness in Schools.

Speaking at the Children’s Nutrition conference in Cardiff last week, Professor Amanda Kirby, medical director of the Dyscovery Centre at the University of Wales in Newport, said if all pupils had the same meals, standards could be better monitored.

“Children learn social values at mealtimes,” she said. “They can reflect on the day’s events and receive guidance.”

But Julia Whitby, head of Ysgol Sant Dunawd near Wrexham, said it was important teachers had a break. “Our teachers don’t eat with pupils, but every Thursday I have a lunch table with a group of children,” she said.

Margaret Morrissey, spokesperson for the National Confederation of Parent Teacher Associations, said parents should still have the chance to opt out. “We’re sometimes treated as criminals if our child has a cake in their lunchbox,” she said. “But it’s my choice with my child.”

Iwan Guy, acting director of the NAHT Cymru, said: “Schools only serve up a small proportion of the food children eat every day.”