Secondary schools across Scotland were yesterday criticised for not showing enough urgency in tackling the country's healthy eating crisis.

A new report by schools inspectors found that, while primaries were progressing well with meeting government targets, progress in secondaries is slower.

HM Inspectorate of Education (HMIE) acknowledged that this was partly because of the influence of adolescent culture, commercial pressures and greater freedom of pupils to go beyond the school grounds at lunchtime. But Graham Donaldson, HM senior chief inspector, warned that poor progress in secondary schools "in part relates to a lack of priority and urgency".

The report, Further Food for Thought, which assesses the Scottish Government's Hungry for Success initiative to improve school meals - launched in 2002 by the former executive - suggested that widening the ban on some types of food in schools may be necessary. But inspectors concluded that even if Hungry for Success worked well, the policy alone would not address the obesity problem - Scots youngsters are some of the most unfit in the world.

More than a third of 12-year-olds are overweight, nearly 20% are obese and 11% severely obese.

"While work in schools can make a significant contribution to improving the diets of children, eating patterns outwith school need to change," the report says.

Professor Mike Lean, head of human nutrition at Glasgow University, said tackling the issue required a Scotland-wide policy of keeping pupils inside the school gates at lunchtime.

But Bill McGregor, general secretary of the Headteachers' Association of Scotland, said that if teachers, parents and pupils of a secondary could all agree on such a policy it could be successful, however that was "unlikely".

"Schools have worked very hard to develop and promote healthy menus," he said.

Adam Ingram, the Children's Minister, said the government was working to promote healthy eating through a National Food Policy, to be launched today.